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Consists of initial stages of television theory.
Citation preview
Th
e b
asi
c fa
ctors
wit
h w
hic
h t
he t
ele
vis
ion
syst
em
mu
st d
eal fo
r su
ccess
ful tr
an
smis
sion
an
d r
ece
pti
on
of
pic
ture
s are
:
(a)
Gro
ss S
tru
ctu
re:
Geom
etr
ic f
orm
an
d a
spect
rati
o o
f th
e p
ictu
re.
(b)
Ima
ge
Con
tin
uit
y:
Sca
nn
ing a
nd
its
sequ
en
ce.
(c)
Nu
mber
of
Sca
nn
ing L
ines
: R
eso
luti
on
of
pic
ture
deta
ils.
(d)
Fli
cker
: In
terl
ace
d s
can
nin
g.
(e)
Fin
e S
tru
ctu
re:
Vert
ical
an
d h
ori
zon
tal
reso
luti
on
.
(f)
Ton
al
Gra
da
tion
: P
ictu
re b
righ
tness
tra
nsf
er
chara
cteri
stic
s of
the s
yst
em
.
� ��������������
Th
e f
ram
e a
dop
ted
in
all
tele
vis
ion
syst
em
s is
rect
an
gu
lar
wit
h w
idth
/heig
ht
rati
o,
i.e.
, asp
ect
rati
o =
4/3
. T
here
are
man
y r
easo
ns
for
this
ch
oic
e. In
hu
man
aff
air
s m
ost
of
the m
oti
on
occ
urs
in t
he h
ori
zon
tal
pla
ne a
nd
so a
larg
er
wid
th i
s d
esi
rable
. T
he e
yes
can
vie
w w
ith
more
ease
an
d c
om
fort
wh
en
th
e w
idth
of
a p
ictu
re i
s m
ore
th
an
its
heig
ht.
Th
e u
sage o
f re
ctan
gu
lar
fram
e in
moti
on
pic
ture
s w
ith
a w
idth
/heig
ht
rati
o o
f 4/3
is
an
oth
er
imp
ort
an
t re
aso
n for
ad
op
tin
g
this
sh
ap
e a
nd
asp
ect
rati
o.
Th
is e
nable
s d
irect
tele
vis
ion
tra
nsm
issi
on
of
film
pro
gra
mm
es
wit
hou
t w
ast
age o
f an
y f
ilm
are
a.
It i
s n
ot
nece
ssary
th
at
the s
ize o
f th
e p
ictu
re p
rod
uce
d o
n t
he r
ece
iver
scre
en
be s
am
e
as
that
bein
g t
ele
vis
ed
bu
t it
is
ess
en
tial th
at
the a
spect
rati
o o
f th
e t
wo b
e s
am
e, oth
erw
ise t
he
scen
e d
eta
ils
wou
ld l
ook
too t
hin
or
too w
ide. T
his
is
ach
ieved
by s
ett
ing t
he m
agn
itu
des
of
the
curr
en
t in
th
e d
efl
ect
ion
coil
s to
corr
ect
valu
es,
both
at
the T
V c
am
era
an
d r
ece
ivin
g p
ictu
re
tube.
An
oth
er
imp
ort
an
t re
qu
irem
en
t is
th
at
the s
am
e c
oord
inate
s sh
ou
ld b
e s
can
ned
at
an
y
inst
an
t both
by t
he c
am
era
tu
be b
eam
an
d t
he p
ictu
re t
ube b
eam
in
th
e r
ece
iver.
Syn
chro
niz
ing
pu
lses
are
tra
nsm
itte
d a
lon
g w
ith
th
e p
ictu
re in
form
ati
on
to a
chie
ve e
xact
con
gru
en
ce b
etw
een
tran
smit
ter
an
d r
ece
iver
scan
nin
g s
yst
em
s.
� ���� ����������
Wh
ile t
ele
vis
ing p
ictu
re e
lem
en
ts o
f th
e fra
me b
y m
ean
s of th
e s
can
nin
g p
roce
ss, it
is
nece
ssary
to p
rese
nt
the p
ictu
re t
o t
he e
ye i
n s
uch
a w
ay t
hat
an
ill
usi
on
of
con
tin
uit
y i
s cr
eate
d a
nd
an
y
��2An
alys
is an
d Sy
nthe
sis o
fTe
levisi
on P
ictur
es
���������������������������������� �!"��
�#m
oti
on
in
th
e s
cen
e a
pp
ears
on
th
e p
ictu
re t
ube s
creen
as
a s
mooth
an
d c
on
tin
uou
s ch
an
ge. T
o
ach
ieve t
his
, ad
van
tage is
tak
en
of ‘p
ers
iste
nce
of vis
ion
’ or
stora
ge c
hara
cteri
stic
s of th
e h
um
an
eye.
Th
is a
rise
s fr
om
th
e f
act
th
at
the s
en
sati
on
pro
du
ced
wh
en
nerv
es
of
the e
ye’s
reti
na a
re
stim
ula
ted
by i
nci
den
t li
gh
t d
oes
not
cease
im
med
iate
ly a
fter
the l
igh
t is
rem
oved
bu
t p
ers
ists
for
abou
t 1/1
6th
of
a s
eco
nd
. T
hu
s if
th
e s
can
nin
g r
ate
per
seco
nd
is
mad
e g
reate
r th
an
six
teen
,
or
the n
um
ber
of
pic
ture
s sh
ow
n p
er
seco
nd
is
more
th
an
six
teen
, th
e e
ye i
s able
to i
nte
gra
te
the c
ha
ngin
g l
evels
of
bri
gh
tness
in
th
e s
cen
e.
So w
hen
th
e p
ictu
re e
lem
en
ts a
re s
can
ned
rap
idly
en
ou
gh
, th
ey a
pp
ear
to t
he e
ye a
s a c
om
ple
te p
ictu
re u
nit
, w
ith
non
e o
f th
e i
nd
ivid
ual
ele
men
ts v
isib
le s
ep
ara
tely
.
In p
rese
nt
da
y m
oti
on
pic
ture
s tw
en
ty-f
ou
r st
ill
pic
ture
s of
the s
cen
e a
re t
ak
en
per
seco
nd
an
d l
ate
r p
roje
cted
on
th
e s
creen
at
the s
am
e r
ate
. E
ach
pic
ture
or
fram
e i
s p
roje
cted
ind
ivid
uall
y a
s a s
till
pic
ture
, bu
t th
ey a
re s
how
n o
ne a
fter
the o
ther
in r
ap
id s
ucc
ess
ion
to
pro
du
ce t
he i
llu
sion
of
con
tin
uou
s m
oti
on
of
the s
cen
e b
ein
g s
how
n.
A s
hu
tter
in t
he p
roje
ctor
rota
tes
in f
ron
t of
the l
igh
t so
urc
e a
nd
all
ow
s th
e f
ilm
to b
e p
roje
cted
on
th
e s
creen
wh
en
th
e
film
fra
me i
s st
ill,
bu
t bla
nk
s ou
t an
y l
igh
t fr
om
th
e s
creen
du
rin
g t
he t
ime w
hen
th
e n
ext
film
fram
e is
bein
g m
oved
in
to p
osi
tion
. A
s a r
esu
lt, a r
ap
id s
ucc
ess
ion
of
stil
l-fi
lm f
ram
es
is s
een
on
the s
creen
. W
ith
all
lig
ht
rem
oved
du
rin
g t
he c
han
ge f
rom
on
e f
ram
e t
o t
he n
ext,
th
e e
ye s
ees
a r
ap
id s
equ
en
ce o
f st
ill
pic
ture
s th
at
pro
vid
es
the i
llu
sion
of
con
tin
uou
s m
oti
on
.
Sca
nn
ing
. A
sim
ilar
pro
cess
is
carr
ied
ou
t in
th
e t
ele
vis
ion
syst
em
. T
he s
cen
e is
scan
ned
rap
idly
both
in
th
e h
ori
zon
tal an
d v
ert
ical d
irect
ion
s si
mu
ltan
eou
sly t
o p
rovid
e s
uff
icie
nt
nu
mber
of
com
ple
te p
ictu
res
or
fram
es
per
seco
nd
to g
ive t
he i
llu
sion
of
con
tin
uou
s m
oti
on
. In
stead
of
the 2
4 a
s in
com
merc
ial
moti
on
pic
ture
pra
ctic
e,
the f
ram
e r
ep
eti
tion
rate
is
25 p
er
seco
nd
in
most
tele
vis
ion
syst
em
s.
Horiz
on
tal
sca
nn
ing
. F
ig.
2.1
(a
) sh
ow
s th
e t
race
an
d r
etr
ace
of
severa
l h
ori
zon
tal
lin
es.
Th
e l
inear
rise
of
curr
en
t in
th
e h
ori
zon
tal
defl
ect
ion
coil
s (F
ig. 2.1
(b))
defl
ect
s th
e b
eam
acr
oss
th
e s
creen
wit
h a
con
tin
uou
s, u
nif
orm
moti
on
for
the t
race
fro
m l
eft
to r
igh
t. A
t th
e
peak
of
the r
ise, th
e s
aw
tooth
wave r
evers
es
dir
ect
ion
an
d d
ecr
ease
s ra
pid
ly t
o its
in
itia
l valu
e.
Th
is f
ast
revers
al
pro
du
ces
the r
etr
ace
or
flyback
. T
he s
tart
of
the h
ori
zon
tal
trace
is
at
the l
eft
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�P
Q��� �"�Q���� ���!"����������
ed
ge o
f ra
ster.
Th
e f
inis
h i
s at
the r
igh
t ed
ge,
wh
ere
th
e f
lyback
pro
du
ces
retr
ace
back
to t
he
left
ed
ge.
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Note
, th
at
‘up
’ on
th
e s
aw
tooth
wave c
orr
esp
on
ds
to h
ori
zon
tal
defl
ect
ion
to t
he r
igh
t.
Th
e h
eavy lin
es
in F
ig. 2.1
(a
) in
dic
ate
th
e u
sefu
l sc
an
nin
g t
ime a
nd
th
e d
ash
ed
lin
es
corr
esp
on
d
to t
he r
etr
ace
tim
e.
Verti
ca
l sca
nn
ing
. T
he s
aw
tooth
cu
rren
t in
th
e v
ert
ical
defl
ect
ion
coil
s (s
ee F
ig.
2.2
)
moves
the e
lect
ron
beam
fro
m t
op
to b
ott
om
of
the r
ast
er
at
a u
nif
orm
sp
eed
wh
ile t
he e
lect
ron
beam
is
bein
g d
efl
ect
ed
hori
zon
tall
y.
Th
us
the b
eem
pro
du
ces
com
ple
te h
ori
zon
tal
lin
es
on
e
belo
w t
he o
ther
wh
ile m
ovin
g f
rom
top
to b
ott
om
.
As
show
n in
Fig
. 2.2
(c)
, th
e t
race
part
of th
e s
aw
tooth
wave for
vert
ical sc
an
nin
g d
efl
ect
s
the b
eam
to t
he b
ott
om
of
the r
ast
er.
Th
en
th
e r
ap
id v
ert
ical
retr
ace
retu
rns
the b
eam
to t
he
top
. N
ote
th
at
the m
axim
um
am
pli
tud
e o
f th
e v
ert
ical
sweep
cu
rren
t bri
ngs
the b
eam
to t
he
bott
om
of
the r
ast
er.
As
show
n i
n F
ig.
2.2
(b)
du
rin
g v
ert
ical
retr
ace
th
e h
ori
zon
tal
scan
nin
g
con
tin
ues
an
d s
evera
l li
nes
get
scan
ned
du
rin
g t
his
peri
od
. B
eca
use
of
moti
on
in
th
e s
cen
e
bein
g t
ele
vis
ed
, th
e i
nfo
rmati
on
or
bri
gh
tness
at
the t
op
of
the t
arg
et
pla
te o
r p
ictu
re t
ube
scre
en
norm
all
y c
han
ges
by t
he t
ime t
he b
eam
retu
rns
to t
he t
op
to r
eco
mm
en
ce t
he w
hole
pro
cess
. T
his
in
form
ati
on
is
pic
ked
up
du
rin
g t
he n
ext
scan
nin
g c
ycl
e a
nd
th
e w
hole
pro
cess
is
rep
eate
d 2
5 t
imes
to c
au
se a
n i
llu
sion
of
con
tin
uit
y.
Th
e a
ctu
al
scan
nin
g s
equ
en
ce i
s h
ow
ever
a lit
tle m
ore
com
ple
x t
han
th
at
just
desc
ribed
an
d is
exp
lain
ed
in
a late
r se
ctio
n o
f th
is c
hap
ter.
It m
ust
how
ever
be n
ote
d,
that
both
du
rin
g h
ori
zon
tal
retr
ace
an
d v
ert
ical
retr
ace
in
terv
als
the s
can
nin
g b
eam
s at
the c
am
era
tu
be a
nd
pic
ture
tu
be a
re b
lan
ked
an
d n
o p
ictu
re in
form
ati
on
is e
ith
er
pic
ked
up
or
rep
rod
uce
d. In
stead
, on
a t
ime d
ivis
ion
basi
s, t
hese
sh
ort
retr
ace
in
terv
als
are
uti
lized
for
tran
smit
tin
g d
isti
nct
narr
ow
pu
lses
to k
eep
th
e s
weep
osc
illa
tors
of
the p
ictu
re
tub
e d
efl
ect
ion
cir
cuit
s o
f th
e r
ece
iver
in s
yn
chro
nis
m w
ith
th
ose o
f th
e c
am
era
at
the
tran
smit
ter.
Th
is e
nsu
res
exact
corr
esp
on
den
ce i
n s
can
nin
g a
t th
e t
wo e
nd
s an
d r
esu
lts
in
dis
tort
ion
less
rep
rod
uct
ion
of
the p
ictu
re d
eta
ils.
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� �������� � �����¡���
Most
sce
nes
have b
righ
tness
gra
dati
on
s in
th
e v
ert
ical
dir
ect
ion
. T
he a
bil
ity o
f th
e s
can
nin
g
beam
to a
llow
rep
rod
uct
ion
of
ele
ctri
cal si
gn
als
acc
ord
ing t
o t
hese
vari
ati
on
s an
d t
he c
ap
abil
ity
of
the h
um
an
eye t
o r
eso
lve t
hese
dis
tin
ctly
, w
hil
e v
iew
ing t
he r
ep
rod
uce
d p
ictu
re, d
ep
en
ds
on
the t
ota
l n
um
ber
of
lin
es
em
plo
yed
for
scan
nin
g.
It i
s p
oss
ible
to a
rriv
e a
t so
me e
stim
ate
s of
the n
um
ber
of
lin
es
nece
ssary
by c
on
sid
eri
ng
the b
ar
patt
ern
sh
ow
n in
Fig
. 2.3
(a
), w
here
alt
ern
ate
lin
es
are
bla
ck a
nd
wh
ite. If
th
e t
hic
kn
ess
of
the s
can
nin
g b
eam
is
equ
al
to t
he w
idth
of
each
wh
ite a
nd
bla
ck b
ar,
an
d t
he n
um
ber
of
scan
nin
g l
ines
is c
hose
n e
qu
al
to t
he n
um
ber
of
bars
, th
e e
lect
rica
l in
form
ati
on
corr
esp
on
din
g
to t
he b
righ
tness
of each
bar
wil
l be c
orr
ect
ly r
ep
rod
uce
d d
uri
ng t
he s
can
nin
g p
roce
ss. O
bvio
usl
y
the g
reate
r th
e n
um
ber
of
lin
es
into
wh
ich
th
e p
ictu
re i
s d
ivid
ed
in
th
e v
ert
ical
pla
ne,
the
bett
er
wil
l b
e t
he r
eso
luti
on
.How
ever,
th
e t
ota
l n
um
ber
of
lin
es
tha
t n
eed
be e
mp
loyed
is
lim
ited
by t
he r
eso
lvin
g c
ap
abil
ity o
f th
e h
um
an
eye a
t th
e m
inim
um
vie
win
g d
ista
nce
.
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Th
e m
axim
um
nu
mber
of alt
ern
ate
lig
ht
an
d d
ark
ele
men
ts (li
nes)
wh
ich
can
be r
eso
lved
by t
he e
ye i
s giv
en
by
Nv =
1 αρ
wh
ere
Nv =
tota
l n
um
ber
of li
nes
(ele
men
ts) to
be r
eso
lved
in
th
e v
ert
ical d
irect
ion
, α =
min
imu
m
reso
lvin
g a
ngle
of
the e
ye e
xp
ress
ed
in
rad
ian
s, a
nd
ρ =
D/H
= v
iew
ing-d
ista
nce
/pic
ture
heig
ht.
For
the e
ye t
his
reso
luti
on
is
dete
rmin
ed
by t
he s
tru
ctu
re o
f th
e r
eti
na, a
nd
th
e b
righ
tness
level
of
the p
ictu
re.
it h
as
been
dete
rmin
ed
exp
eri
men
tly t
ha
t w
ith
rea
son
ab
le b
righ
tness
vari
ati
on
s an
d a
min
imu
m v
iew
ing d
ista
nce
of
fou
r ti
mes
the p
ictu
re h
eig
ht
(D/H
= 4
), t
he
an
gle
th
at
an
y t
wo a
dja
cen
t ele
men
ts m
ust
su
bte
nd
at
the e
ye f
or
dis
tin
ct r
eso
luti
on
is
ap
pro
xim
ate
ly o
ne m
inu
te (
1/6
0 d
egre
e).
Th
is i
s il
lust
rate
d i
n F
ig.
2.3
(b).
Su
bst
itu
tin
g t
hese
valu
es
of α
an
d ρ
we g
et
Nv =
1
180
160
4860
(/
/)
π×
×≈
Th
us
if t
he t
ota
l n
um
ber
of
scan
nin
g l
ines
is c
hose
n c
lose
to 8
60 a
nd
th
e s
can
nin
g b
eam
as
illu
stra
ted
in
Fig
. 2.3
(a
) ju
st p
ass
es
over
each
bar
(lin
e)
sep
ara
tely
wh
ile s
can
nin
g a
ll t
he lin
es
from
top
to b
ott
om
of
the p
ictu
re f
ram
e,
a d
isti
nct
pic
k u
p o
f th
e p
ictu
re i
nfo
rmati
on
resu
lts
an
d t
his
is
the b
est
th
at
can
be e
xp
ect
ed
fro
m t
he s
yst
em
. T
his
perh
ap
s exp
lain
s th
e u
se o
f 819
lin
es
in t
he o
rigin
al
Fre
nch
TV
syst
em
.
���������������������������������� �!"��
º�In
pra
ctic
e h
ow
ever,
th
e p
ictu
re e
lem
en
ts a
re n
ot
arr
an
ged
as
equ
all
y s
pace
d s
egm
en
ts
bu
t h
ave r
an
dom
dis
trib
uti
on
of
bla
ck,
gre
y a
nd
wh
ite d
ep
en
din
g o
n t
he n
atu
re o
f th
e p
ictu
re
deta
ils
or
the s
cen
e u
nd
er
con
sid
era
tion
. S
tati
stic
al
an
aly
sis
an
d s
ubje
ctiv
e t
est
s ca
rrie
d o
ut
to
dete
rmin
e t
he a
vera
ge n
um
ber
of
eff
ect
ive l
ines
suggest
th
at
abou
t 70 p
er
cen
t of
the t
ota
l
lin
es
or
segm
en
ts g
et
sep
ara
tely
sca
nn
ed
in
th
e v
ert
ical
dir
ect
ion
an
d t
he r
em
ain
ing 3
0 p
er
cen
t get
merg
ed
wit
h o
ther
ele
men
ts d
ue t
o t
he b
eam
sp
ot
fall
ing e
qu
all
y o
n t
wo c
on
secu
tive
lin
es.
Th
is i
s il
lust
rate
d i
n F
ig.
2.3
(c)
. T
hu
s th
e e
ffect
ive n
um
ber
of
lin
es
dis
tin
ctly
reso
lved
,
i.e.
, Nr =
Nv ×
k, w
here
k is
the r
eso
luti
on
fact
or
wh
ose
valu
e lie
s betw
een
0.6
5 t
o 0
.75. A
ssu
min
g
the v
alu
e o
f k =
0.7
we g
et,
Nr
= N
v ×
k =
860 ×
0.7
= 6
02.
How
ever,
th
ere
are
oth
er
fact
ors
wh
ich
als
o i
nfl
uen
ce t
he c
hoic
e o
f to
tal
nu
mber
of
lin
es
in a
TV
syst
em
. T
est
s co
nd
uct
ed
wit
h m
an
y o
bse
rvers
have s
how
n t
hat
thou
gh
th
e e
ye c
an
dete
ct t
he e
ffect
ive s
harp
ness
pro
vid
ed
by a
bou
t 800 s
can
nin
g l
ines,
bu
t th
e i
mp
rovem
en
t is
not
very
sig
nif
ican
t w
ith
lin
e n
um
bers
gre
ate
r th
an
500 w
hil
e v
iew
ing p
ictu
res
havin
g m
oti
on
.
Als
o t
he c
han
nel
ban
dw
idth
in
crease
s w
ith
in
crease
in
nu
mber
of
lin
es
an
d t
his
not
on
ly a
dd
s
to t
he c
ost
of th
e s
yst
em
bu
t als
o r
ed
uce
s th
e n
um
ber
of te
levis
ion
ch
an
nels
th
at
can
be p
rovid
ed
in a
giv
en
VH
F o
r U
HF
tra
nsm
issi
on
ban
d.
Th
us
as
a c
om
pro
mis
e b
etw
een
qu
ali
ty a
nd
cost
,
the t
ota
l n
um
ber
of
lin
es
incl
usi
ve o
f th
ose
lost
du
rin
g v
ert
ical
retr
ace
has
been
ch
ose
n t
o b
e
625 i
n t
he 6
25-B
mon
och
rom
e T
V s
yst
em
. In
th
e 5
25 l
ine A
meri
can
syst
em
, th
e t
ota
l n
um
ber
of
lin
es
has
been
fix
ed
at
525 b
eca
use
of
a s
om
ew
hat
hig
her
scan
nin
g r
ate
em
plo
yed
in
th
is
syst
em
. � �þ ¡�ÿ�A
lth
ou
gh
th
e r
ate
of
24 p
ictu
res
per
seco
nd
in
moti
on
pic
ture
s an
d t
hat
of
scan
nin
g 2
5 f
ram
es
per
seco
nd
in
tele
vis
ion
pic
ture
s is
en
ou
gh
to c
au
se a
n i
llu
sion
of
con
tin
uit
y, th
ey a
re n
ot
rap
id
en
ou
gh
to a
llow
th
e b
irgh
tness
of
on
e p
ictu
re o
r fr
am
e t
o b
len
d s
mooth
ly i
nto
th
e n
ext
thro
ugh
the t
ime w
hen
th
e s
creen
is
bla
nk
ed
betw
een
su
ccess
ive f
ram
es.
Th
is r
esu
lts
in a
defi
nit
e
flic
ker
of
ligh
t th
at
is v
ery
an
noyin
g t
o t
he o
bse
rver
wh
en
th
e s
creen
is
ma
de a
ltern
ate
ly
bri
gh
t an
d d
ark
.
Th
is p
roble
m i
s so
lved
in
moti
on
pic
ture
s by s
how
ing e
ach
pic
ture
tw
ice,
so t
hat
48
vie
ws
of
the s
cen
e a
re s
how
n p
er
seco
nd
alt
hou
gh
th
ere
are
sti
ll t
he s
am
e 2
4 p
ictu
re f
ram
es
per
seco
nd
. A
s a r
esu
lt o
f th
e i
ncr
ease
d b
lan
kin
g r
ate
, fl
ick
er
is e
lim
inate
d.
Inte
rla
ced
sca
nn
ing. In
tele
vis
ion
pic
ture
s an
eff
ect
ive r
ate
of 50 v
ert
ical sc
an
s p
er
seco
nd
is u
tili
zed
to r
ed
uce
fli
cker.
Th
is i
s acc
om
pli
shed
by i
ncr
easi
ng t
he d
ow
nw
ard
rate
of
travel
of
the s
can
nin
g e
lect
ron
beam
, so
th
at
every
alt
ern
ate
lin
e g
ets
sca
nn
ed
in
stead
of every
su
ccess
ive
lin
e.
Th
en
, w
hen
th
e b
eam
reach
es
the b
ott
om
of
the p
ictu
re f
ram
e,
it q
uic
kly
retu
rns
to t
he
top
to s
can
th
ose
lin
es
that
were
mis
sed
in
th
e p
revio
us
scan
nin
g.
Th
us
the t
ota
l n
um
ber
of
lin
es
are
div
ided
in
to t
wo g
rou
ps
call
ed
‘fi
eld
s’. E
ach
fie
ld i
s sc
an
ned
alt
ern
ate
ly.
Th
is m
eth
od
of
scan
nin
g i
s k
now
n a
s in
terl
ace
d s
can
nin
g a
nd
is
illu
stra
ted
in
Fig
. 2.4
. It
red
uce
s fl
ick
er
to
an
acc
ep
table
level
sin
ce t
he a
rea o
f th
e s
creen
is
covere
d a
t tw
ice t
he r
ate
. T
his
is
lik
e r
ead
ing
alt
ern
ate
lin
es
of
a p
age f
rom
top
to b
ott
om
on
ce a
nd
th
en
goin
g b
ack
to r
ead
th
e r
em
ain
ing
lin
es
dow
n t
o t
he b
ott
om
.
ºº
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In t
he 6
25 l
ime m
on
och
rom
e s
yst
em
, fo
r su
ccess
ful
inte
rlace
d s
can
nin
g, th
e 6
25 l
ines
of
each
fra
me o
r p
ictu
re a
re d
ivid
ed
in
to s
ets
of
312.5
lin
es
an
d e
ach
set
is s
can
ned
alt
ern
ate
ly t
o
cover
the e
nti
re p
ictu
re a
rea. T
o a
chie
ve t
his
th
e h
ori
zon
tal
sweep
osc
illa
tor
is m
ad
e t
o w
ork
at
a f
requ
en
cy o
f 15625 H
z (
312.5
× 5
0 =
15625)
to s
can
th
e s
am
e n
um
ber
of
lin
es
per
fram
e
(15625/2
5 =
625 l
ines)
, bu
t th
e v
ert
ical
sweep
cir
cuit
is
run
at
a f
requ
en
cy o
f 50 i
nst
ead
of
25
Hz.
Note
th
at
sin
ce t
he b
eam
is
now
defl
ect
ed
fro
m t
op
to b
ott
om
in
half
th
e t
ime a
nd
th
e
hori
zon
tal
osc
illa
tor
is s
till
op
era
tin
g a
t 15625 H
z,
on
ly h
alf
th
e t
ota
l li
nes,
i.e
., 3
12
.5 (
62
5/2
=
312.5
) get
scan
ned
du
rin
g e
ach
vert
ical
sweep
. S
ince
th
e f
irst
fie
ld e
nd
s in
a h
alf
lin
e a
nd
th
e
seco
nd
fie
ld c
om
men
ces
at
mid
dle
of
the l
ine o
n t
he t
op
of
the t
arg
et
pla
te o
r sc
reen
(se
e
Fig
.2.4
), t
he b
eam
is
able
to s
can
th
e r
em
ain
ing 3
12.5
alt
ern
ate
lin
es
du
rin
g i
ts d
ow
nw
ard
jou
rney.
In a
ll t
hen
, th
e b
eam
sca
ns
625 l
ines
(312.5
× 2
= 6
25)
per
fram
e a
t th
e s
am
e r
ate
of
15625 l
ines
(312.5
× 5
0 =
15625)
per
seco
nd
. T
here
fore
, w
ith
in
terl
ace
d s
can
nin
g t
he f
lick
er
eff
ect
is
eli
min
ate
d w
ith
ou
t in
creasi
ng t
he s
peed
of
scan
nin
g, w
hic
h i
n t
urn
does
not
need
an
y
incr
ease
in
th
e c
han
nel
ban
dw
idth
.
It m
ay b
e n
ote
d t
hat
the f
ram
e r
ep
eti
tion
rate
of
25 (
rath
er
than
24 a
s u
sed
in
moti
on
pic
ture
s) w
as
chose
n t
o m
ak
e t
he f
ield
fre
qu
en
cy e
qu
al
to t
he p
ow
er
lin
e f
requ
en
cy o
f 50 H
z.
Th
is h
elp
s in
red
uci
ng t
he u
nd
esi
red
eff
ect
s of
hu
m d
ue t
o p
ick
up
fro
m t
he m
ain
s, b
eca
use
then
su
ch e
ffect
s in
th
e p
ictu
re s
tay s
till
, in
stead
of
dri
ftin
g u
p o
r d
ow
n o
n t
he s
creen
. In
th
e
Am
eri
can
TV
syst
em
, a f
ield
fre
qu
en
cy o
f 60 w
as
ad
op
ted
beca
use
th
e s
up
ply
fre
qu
en
cy i
s
60
Hz i
n U
SA
. T
his
bri
ngs
the t
ota
l n
um
ber
of
lin
es
scan
ned
per
seco
nd
((5
25/2
) ×
60 =
15750)
lin
es
to p
ract
icall
y t
he s
am
e a
s in
th
e 6
25 l
ine s
yst
em
.
Sca
nn
ing p
erio
ds.
Th
e w
avesh
ap
es
of
both
hori
zon
tal
an
d v
ert
ical
sweep
cu
rren
ts a
re
show
n i
n F
ig. 2.5
. A
s sh
ow
n t
here
th
e r
etr
ace
tim
es
involv
ed
(both
hori
zon
tal
an
d v
ert
ical)
are
du
e t
o p
hysi
cal
lim
itati
on
s of
pra
ctic
al
scan
nin
g s
yst
em
s an
d a
re n
ot
uti
lized
for
tran
smit
tin
g
or
rece
ivin
g a
ny v
ideo s
ign
al.
Th
e n
om
inal d
ura
tion
of th
e h
ori
zon
tal li
ne a
s sh
ow
n in
Fig
.2.5
(a)
is 6
4 µ
s (1
06/1
5625 =
64 µ
s), ou
t of
wh
ich
th
e a
ctiv
e lin
e p
eri
od
is
52 µ
s an
d t
he r
em
ain
ing 1
2 µ
s
���������������������������������� �!"��
º"is
th
e lin
e b
lan
kin
g p
eri
od
. T
he b
eam
retu
rns
du
rin
g t
his
sh
ort
in
terv
al to
th
e e
xtr
em
e left
sid
e
of
the f
ram
e t
o s
tart
tra
cin
g t
he n
ext
lin
e.
Sim
ilarl
y w
ith
th
e f
ield
fre
qu
en
cy s
et
at
50 H
z,
the n
om
inal
du
rati
on
of
the v
ert
ical
trace
(se
e F
ig.
2.5
(b))
is
20 m
s (1
/50 =
20 m
s).
Ou
t of
this
peri
od
of
20 m
s, 1
8.7
20 m
s are
sp
en
t
in b
rin
gin
g t
he b
eam
fro
m t
op
to b
ott
om
an
d t
he r
em
ain
ing 1
.280 m
s is
tak
en
by t
he b
eam
to
retu
rn b
ack
to t
he t
op
to c
om
men
ce t
he n
ext
cycl
e.
Sin
ce t
he h
ori
zon
tal
an
d v
ert
ical
sweep
osc
illa
tors
op
era
te c
on
tin
uou
sly t
o a
chie
ve t
he fast
sequ
en
ce o
f in
terl
ace
d s
can
nin
g, 2
0 h
ori
zon
tal
lin
es
1280
64
20
µ
µ
s
sli
nes
=F HG
I KJ get
trace
d d
uri
ng e
ach
vert
ical
retr
ace
in
terv
al.
Th
us
40 s
can
nin
g
lin
es
are
lost
per
fram
e,
as
bla
nk
ed
lin
es
du
rin
g t
he r
etr
ace
in
terv
al
of
two f
ield
s. T
his
leaves
the a
ctiv
e n
um
ber
of
lin
es,
Na, fo
r sc
an
nin
g t
he p
ictu
re d
eta
ils
equ
al
to 6
25 –
40 =
585, in
stead
of
the 6
25 l
ines
act
uall
y s
can
ned
per
fram
e.
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Sca
nn
ing s
equ
ence
. T
he c
om
ple
te g
eom
etr
y o
f th
e s
tan
dard
in
terl
ace
d s
can
nin
g p
att
ern
is i
llu
stra
ted
in
Fig
. 2.6
. N
ote
th
at
the l
ines
are
nu
mbere
d i
n t
he s
equ
en
ce i
n w
hic
h t
hese
are
act
uall
y s
can
ned
. D
uri
ng t
he f
irst
vert
ical
trace
act
uall
y 2
92.5
lin
es
are
sca
nn
ed
. T
he b
eam
start
s at
A, an
d s
weep
s acr
oss
th
e f
ram
e w
ith
un
iform
velo
city
to c
over
all
th
e p
ictu
re e
lem
en
ts
in o
ne h
ori
zon
tal
lin
e. A
t th
e e
nd
of
this
tra
ce t
he b
eam
th
en
retr
ace
s ra
pid
ly t
o t
he l
eft
sid
e o
f
the f
ram
e a
s sh
ow
n b
y t
he d
ash
ed
lin
e i
n t
he i
llu
stra
tion
to b
egin
th
e n
ext
hori
zon
tal
lin
e.
Note
th
at
the h
ori
zon
tal li
nes
slop
e d
ow
nw
ard
s in
th
e d
irect
ion
of sc
an
nin
g b
eca
use
th
e v
ert
ical
defl
ect
ing c
urr
en
t si
mu
lta
neou
sly p
rod
uce
s a
vert
ica
l sc
an
nin
g m
oti
on
, w
hic
h i
s very
slo
w
ºq
Q��� �"�Q���� ���!"����������
com
pare
d w
ith
hori
zon
tal sc
an
nin
g. T
he s
lop
e o
f th
e h
ori
zon
tal tr
ace
fro
m left
to r
igh
t is
gre
ate
r
than
du
rin
g r
etr
ace
fro
m r
igh
t to
left
. T
he r
easo
n i
s th
at
the f
ast
er
retr
ace
does
not
all
ow
th
e
beam
so m
uch
tim
e t
o b
e d
efl
ect
ed
vert
icall
y.
Aft
er
lin
e o
ne,
the b
eam
is
at
the l
eft
sid
e r
ead
y
to s
can
lin
e 3
, om
itti
ng t
he s
eco
nd
lin
e.
How
ever,
as
men
tion
ed
ea
rlie
r it
is
con
ven
ien
t to
nu
mber
the lin
es
as
they a
re s
can
ned
an
d s
o t
he n
ext
scan
ned
lin
e s
kip
pin
g o
ne lin
e, i
s n
um
bere
d
two a
nd
not
thre
e.
Th
is p
roce
ss c
on
tin
ues
till
th
e l
ast
lin
e g
ets
sca
nn
ed
half
wh
en
th
e v
ert
ical
moti
on
reach
es
the b
ott
om
of
the r
ast
er
or
fram
e.
As
exp
lain
ed
earl
ier
skip
pin
g o
f li
nes
is
acc
om
pli
shed
by d
ou
bli
ng t
he v
ert
ical
scan
nin
g f
requ
en
cy f
rom
th
e f
ram
e o
r p
ictu
re r
ep
eti
tion
rate
of
25 t
o t
he f
ield
fre
qu
en
cy o
f 50 H
z.
Wit
h t
he f
ield
fre
qu
en
cy o
f 50 H
z t
he h
eig
ht
of
the
rast
er
is s
o s
et
that
292.5
lin
es
get
scan
ned
as
the b
eam
tra
vels
fro
m t
op
to b
ott
om
an
d r
each
es
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poin
t B
. N
ow
th
e r
etr
ace
sta
rts
an
d t
ak
es
a p
eri
od
equ
al
to 2
0 h
ori
zon
tal
lin
e p
eri
od
s to
reach
the t
op
mark
ed
C.
Th
ese
20 l
ines
are
kn
ow
n a
s in
act
ive l
ines,
as
the s
can
nin
g b
eam
is
cut-
off
du
rin
g t
his
peri
od
. T
hu
s th
e s
eco
nd
fie
ld s
tart
s at
the m
idd
le o
f th
e r
ast
er
an
d t
he f
irst
lin
e
scan
ned
is
the 2
nd
half
of
lin
e n
um
ber
313. T
he s
can
nin
g o
f se
con
d f
ield
, st
art
ing a
t th
e m
idd
le
of th
e r
ast
er
au
tom
ati
call
y e
nable
s th
e b
eam
to s
can
th
e a
ltern
ati
ve lin
es
left
un
scan
ned
du
rin
g
the f
irst
fie
ld.
Th
e v
ert
ical
scan
nin
g m
oti
on
oth
erw
ise i
s exact
ly t
he s
am
e a
s in
th
e p
revio
us
field
giv
ing a
ll t
he h
ori
zon
tal
lin
es
the s
am
e s
lop
e d
ow
nw
ard
s in
th
e d
irect
ion
of
scan
nin
g.
As
a r
esu
lt 2
92.5
lin
es
again
get
scan
ned
an
d t
he b
eam
reach
es
the b
ott
om
of
the f
ram
e w
hen
it
has
com
ple
ted
fu
ll s
can
nin
g o
f li
ne n
um
ber
605. T
he i
nact
ive v
ert
ical
retr
ace
again
begin
s an
d
bri
ngs
the b
eam
back
to t
he t
op
at
poin
t A
in
a p
eri
od
du
rin
g w
hic
h 2
0 b
lan
ked
hori
zon
tal li
nes
(605 t
o 6
25)
get
scan
ned
. B
ack
at
poin
t A
, th
e s
can
nin
g b
eam
has
just
com
ple
ted
tw
o f
ield
s or
on
e f
ram
e a
nd
is
read
y t
o s
tart
th
e t
hir
d f
ield
coveri
ng t
he s
am
e a
rea (
no.
of
lin
es)
as
scan
ned
du
rin
g t
he f
irst
fie
ld.
Th
is p
roce
ss (
of
scan
nin
g f
ield
s) i
s co
nti
nu
ed
at
a f
ast
rate
of
50 t
imes
a
seco
nd
, w
hic
h n
ot
on
ly c
reate
s an
ill
usi
on
of
con
tin
uit
y b
ut
als
o s
olv
es
the p
roble
m o
f fl
ick
er
sati
sfa
ctori
ly.
���������������������������������� �!"��
º�
� �� ���������
Th
e a
bil
ity o
f th
e i
mage r
ep
rod
uci
ng s
yst
em
to r
ep
rese
nt
the f
ine s
tru
ctu
re o
f an
obje
ct i
s
kn
ow
n a
s it
s re
solv
ing p
ow
er
or
reso
luti
on
. It
is
nece
ssary
to c
on
sid
er
this
asp
ect
sep
ara
tely
in
the v
ert
ical
an
d h
ori
zon
tal
pla
nes
of
the p
ictu
re.
Ver
tica
l re
solu
tion
. T
he e
xte
nt
to w
hic
h t
he s
can
nin
g s
yst
em
is
cap
ab
le o
f re
solv
ing
pic
ture
deta
ils
in t
he v
ert
ical
dir
ect
ion
is
refe
rred
to a
s it
s vert
ical
reso
luti
on
. It
has
alr
ead
y
been
exp
lain
ed
th
at
the v
ert
ical
reso
luti
on
is
a f
un
ctio
n o
f th
e s
can
nin
g l
ines
into
wh
ich
th
e
pic
ture
is
div
ided
in
th
e v
ert
ical
pla
ne.
Base
d o
n t
hat
dis
cuss
ion
th
e v
ert
ical
reso
luti
on
in
th
e
625 l
ines
syst
em
can
th
en
be e
xp
ress
ed
as
Vr
= N
a ×
k
wh
ere
Vr
is t
he v
ert
ical
reso
luti
on
exp
ress
ed
in
nu
mber
of
lin
es,
Na i
s th
e a
ctiv
e n
um
ber
of
lin
es
an
d k
is
the r
eso
luti
on
fact
or
(als
o k
now
n a
s K
ell
fact
or)
.
Ass
um
ing a
reaso
nable
valu
e o
f k =
0.6
9,
Vr
= 5
85 ×
0.6
9 =
400 l
ines
It i
s of
inte
rest
to n
ote
th
at
the c
orr
esp
on
din
g r
eso
luti
on
of
35 m
m m
oti
on
pic
ture
s is
abou
t 515 l
ines
an
d t
hu
s p
rod
uce
s gre
ate
r d
eta
ils
as
com
pare
d t
o t
ele
vis
ion
pic
ture
s.
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º�
Q��� �"�Q���� ���!"����������
Hori
zon
tal re
solu
tion
. T
he c
ap
abil
ity o
f th
e s
yst
em
to r
eso
lve m
axim
um
nu
mber
of p
ictu
re
ele
men
ts a
lon
g t
he s
can
nin
g l
ines
dete
rmin
es
hori
zon
tal
reso
luti
on
. T
his
can
be e
valu
ate
d b
y
con
sid
eri
ng a
vert
ical
bar
patt
ern
as
show
n i
n F
ig.
2.7
(a).
It
wou
ld b
e r
eali
stic
to a
im a
t equ
al
vert
ical
an
d h
ori
zon
tal
reso
luti
on
an
d a
s su
ch t
he n
um
ber
of
alt
ern
ate
bla
ck a
nd
wh
ite b
ars
that
shou
ld b
e c
on
sid
ere
d i
s equ
al
to
Na ×
asp
ect
rati
o =
585 ×
4/3
= 7
80
Befo
re p
roce
ed
ing f
urt
her
it m
ust
be r
eco
gn
ised
th
at
as
all
lin
es
in t
he v
ert
ical
pla
ne a
re
not
full
y e
ffect
ive,
in a
sim
ilar
way a
ll p
art
s of
an
in
div
idu
al
lin
e a
re n
ot
full
y e
ffect
ive a
ll t
he
tim
e. A
s exp
lain
ed
earl
ier,
it
ult
imate
ly d
ep
en
ds
on
th
e r
an
dom
dis
trib
uti
on
of
bla
ck a
nd
wh
ite
are
as
in t
he p
ictu
re.
Th
us
for
equ
al
vert
ical
an
d h
ori
zon
tal
reso
luti
on
, th
e s
am
e r
eso
luti
on
fact
or
may b
e u
sed
wh
ile d
ete
rmin
ing t
he e
ffect
ive n
um
ber
of
dis
tin
ct p
ictu
re e
lem
en
ts i
n a
hori
zon
tal
lin
e.
Th
ere
fore
, th
e e
ffect
ive n
um
ber
of
alt
ern
ate
bla
ck a
nd
wh
ite s
egm
en
ts i
n o
ne
hori
zon
tal
lin
e f
or
equ
al
vert
ical
an
d h
ori
zon
tal
reso
luti
on
are
:
N =
Na ×
asp
ect
rati
o ×
k =
585 ×
4/3
× 0
.69 =
533
To r
eso
lve t
hese
533 s
qu
are
s or
pic
ture
ele
men
ts t
he s
can
nin
g s
pot
mu
st d
evelo
p a
vid
eo
sign
al
of
squ
are
wa
ve n
atu
re s
wit
chin
g c
on
tin
uou
sly a
lon
g t
he l
ine b
etw
een
volt
age l
evels
corr
esp
on
din
g t
o b
lack
an
d p
eak
wh
ite. T
his
is
show
n a
lon
g t
he b
ar
patt
ern
dra
wn
in
Fig
.2.7
(a).
Sin
ce a
lon
g o
ne l
ine t
here
are
533/2
≈ 2
67 c
om
ple
te c
ycl
ic c
han
ges,
267 c
om
ple
te s
qu
are
wave
cycl
es
get
gen
era
ted
du
rin
g t
he t
ime t
he b
eam
tak
es
to t
ravel
alo
ng t
he w
idth
of
the p
att
ern
.
Th
us
the t
ime d
ura
tion
th o
f on
e s
qu
are
wave c
ycl
e i
s equ
al
to
t h=
act
ive p
eri
od
of
each
hori
zon
tal
lin
e
nu
mber
of
cycl
es
= 5
21
0
26
7
6×
−
seco
nd
s
∴th
g f
requ
en
cy o
f th
e p
eri
od
ic w
ave
fh =
1
267
10
52
6
t h=
× =
5 M
Hz
Sin
ce t
he c
on
sid
era
tion
of
both
vert
ical
an
d h
ori
zon
tal
reso
luti
on
s is
base
d o
n i
den
tica
l
bla
ck a
nd
wh
ite b
ars
in
th
e h
ori
zon
tal
an
d v
ert
ical
pla
nes
of
the p
ictu
re f
ram
e,
it a
mou
nts
to
con
sid
eri
ng a
ch
ess
board
patt
ern
as
the m
ost
str
ingen
t ca
se a
nd
is
illu
stra
ted
in
Fig
. 2.7
(b).
Here
each
alt
ern
ate
bla
ck a
nd
wh
ite s
qu
are
ele
men
t ta
kes
the p
lace
of
bars
for
dete
rmin
ing
the c
ap
abil
ity o
f th
e s
can
nin
g s
yst
em
to r
ep
rod
uce
th
e fin
e s
tru
ctu
re o
f th
e o
bje
ct b
ein
g t
ele
vis
ed
.
Th
e a
ctu
al
size o
f ea
ch s
qu
are
ele
men
t in
th
e c
hess
pa
ttern
is
very
sm
all
an
d i
s eq
ua
l to
thic
kn
ess
of
the s
can
nin
g b
eam
. It
wou
ld b
e i
nst
ruct
ive t
o k
now
as
an
ill
ust
rati
on
th
at
the s
ize
of
such
a s
qu
are
ele
men
t on
th
e s
creen
of
a 5
1 c
m p
ictu
re t
ube i
s abou
t 0.5
mm
2 o
nly
.
Sin
ce t
he s
paci
ng o
f th
ese
sm
all
ele
men
ts i
n t
he a
bove c
on
sid
era
tion
corr
esp
on
ds
to t
he
lim
itin
g r
eso
luti
on
of
the e
ye, it
wil
l d
isti
ngu
ish
on
ly t
he a
ltern
ate
lig
ht
an
d d
ark
are
as
bu
t n
ot
the s
hap
e o
f th
e v
ari
ati
on
s alo
ng t
he s
can
nin
g l
ine.
Th
us
the e
ye w
ill
fail
to d
isti
ngu
ish
th
e
dif
fere
nce
betw
een
a s
qu
are
wave o
f bri
gh
tness
vari
ati
on
an
d a
sin
e w
ave o
f bri
gh
tness
vari
ati
on
in t
he r
ep
rod
uce
d p
ictu
re.
Th
ere
fore
, if
th
e a
mp
lifi
er
for
the s
qu
are
-wave s
ign
al
is c
ap
able
of
rep
rod
uci
ng a
sin
e-w
ave o
f fr
eq
uen
cy e
qu
al
to t
he r
ep
eti
tion
fre
qu
en
cy o
f th
e r
ect
an
gu
lar
wave, it
is
sati
sfact
ory
for
the p
urp
ose
of
TV
sig
nals
. It
may b
e m
en
tion
ed
th
at
even
oth
erw
ise
���������������������������������� �!"��
º#to
ha
nd
le a
5 M
Hz s
qu
are
wa
ve w
ou
ld n
ece
ssit
ate
rep
rod
uct
ion
up
to 1
1th
ha
rmon
ic o
f a
peri
od
ic s
inu
soid
al
wave o
f 5 M
Hz b
y t
he a
ssoci
ate
d e
lect
ron
ic c
ircu
itry
. T
his
wou
ld m
ean
a
ban
dw
idth
of
atl
east
up
to 5
× 1
1 =
55 M
Hz w
hic
h is
exce
ssiv
e a
nd
alm
ost
im
poss
ible
to p
rovid
e
in p
ract
ice.
An
oth
er
just
ific
ati
on
for
rest
rict
ing t
he b
an
dw
idth
up
to 5
MH
z i
s th
at
in p
ract
ice
it i
s ra
re w
hen
alt
ern
ate
pic
ture
ele
men
ts a
re b
lack
an
d w
hit
e t
hro
ugh
ou
t th
e p
ictu
re w
idth
an
d h
eig
ht,
an
d a
ban
dw
idth
up
to 5
MH
z h
as
been
fou
nd
to b
e q
uit
e a
dequ
ate
to p
rod
uce
most
deta
ils
of
the s
cen
e b
ein
g t
ele
vis
ed
.
Th
ere
fore
, th
e h
igh
est
ap
pro
xim
ate
mod
ula
tin
g fre
qu
en
cy ‘f
h’ t
hat
the 6
25 lin
e t
ele
vis
ion
syst
em
mu
st b
e c
ap
able
of
han
dli
ng f
or
succ
ess
ful tr
an
smis
sion
an
d r
ece
pti
on
of
pic
ture
deta
ils
is
fh =
No.
of a
ctiv
e l
ines
asp
ect
ra
tio
reso
luti
on f
act
or
2
tim
e d
ura
tion
of
on
e a
ctiv
e l
ine
××
×
=
585
43
069
252
10
6
××
××
−
/.
≈
5 M
Hz
In t
he s
eco
nd
(525 l
ine)
wid
ely
use
d t
ele
vis
ion
syst
em
, w
here
th
e a
ctiv
e n
um
ber
of
lin
es
is 4
85 a
nd
th
e d
ura
tion
of
on
e a
ctiv
e l
ine i
s 57 µ
s, t
he h
igh
est
mod
ula
tin
g f
requ
en
cy f
h ≈
4
MH
z.
Th
is e
xp
lain
s th
e a
lloca
tion
of
6 M
Hz a
s th
e c
ha
nn
el
ba
nd
wid
th i
n U
SA
an
d o
ther
cou
ntr
ies
em
plo
yin
g t
he 5
25 l
ine s
yst
em
in
com
pari
son
to a
ch
an
nel
ban
dw
idth
all
oca
tion
of
7
MH
z i
n c
ou
ntr
ies
tha
t h
ave a
dop
ted
th
e 6
25
lin
e s
yst
em
. S
imil
arl
y i
n t
he F
ren
ch 8
19
TV
syst
em
wh
ere
th
e h
igh
est
mod
ula
tin
g f
requ
en
cy c
om
es
to 1
0.4
MH
z a
ch
an
nel
ban
dw
idth
of
14
MH
z i
s all
ow
ed
.
Colo
ur
reso
luti
on
an
d b
an
dw
idth
. A
s exp
lain
ed
above a
ban
dw
idth
of
5 M
Hz (
4 M
Hz i
n
the A
meri
can
syst
em
) is
need
ed
for
tran
smis
sion
of m
axim
um
hori
zon
tal d
eta
il in
mon
och
rom
e.
How
ever,
th
is b
an
dw
idth
is
not
nece
ssary
for
the c
olo
ur
vid
eo s
ign
als
. T
he r
easo
n i
s th
at
the
hu
man
eye’s
colo
ur
resp
on
se c
han
ges
wit
h t
he s
ize o
f th
e o
bje
ct. F
or
very
sm
all
obje
cts
the e
ye
can
perc
eiv
e o
nly
th
e b
righ
tness
rath
er
than
th
e c
olo
urs
in
th
e s
cen
e.
Perc
ep
tion
of
colo
urs
by
the e
ye is
lim
ited
to o
bje
cts
wh
ich
resu
lt in
a v
ideo f
requ
en
cy o
utp
ut
up
to a
bou
t 1.5
MH
z. T
hu
s
the c
olo
ur
info
rmati
on
need
s m
uch
less
ban
dw
idth
th
an
mon
och
rom
e d
eta
ils
an
d c
an
be e
asi
ly
acc
om
mod
ate
d i
n t
he c
han
nel
ban
dw
idth
all
ott
ed
for
mon
och
rom
e t
ran
smis
sion
.
Low
-fre
qu
ency
req
uir
emen
ts.
Th
e a
naly
sis
of
the s
ign
als
pro
du
ced
by t
he b
ar
patt
ern
giv
es
no i
nfo
rmati
on
regard
ing t
he l
ow
-fre
qu
en
cy r
equ
irem
en
t of
a v
ideo a
mp
lifi
er
use
d t
o
han
dle
su
ch s
ign
als
. T
his
requ
irem
en
t m
ay b
e d
ete
rmin
ed
fro
m c
on
sid
era
tion
of
a p
att
ern
show
n i
n F
ig.
2.8
(a).
Th
e s
ign
al
ou
tpu
t d
uri
ng v
ert
ica
l excu
rsio
ns
of
the b
ea
m w
ou
ld b
e a
squ
are
wave (
see F
ig. 2.8
(b))
at
vert
ical
field
fre
qu
en
cy. It
is
ap
pare
nt
then
, th
at
an
y a
mp
lifi
er
cap
able
of
rep
rod
uci
ng t
his
wavefo
rm w
ou
ld b
e r
equ
ired
to h
ave g
ood
squ
are
-wave r
esp
on
se a
t
50 H
z. A
ny d
egra
dati
on
in
resp
on
se a
s sh
ow
n in
Fig
. 2.8
(c) w
ou
ld r
esu
lt in
bri
gh
tness
dis
tort
ion
.
In o
rder
to h
ave s
ati
sfact
ory
squ
are
-wave r
esp
on
se a
t fi
eld
fre
qu
en
cy,
an
am
pli
fier
mu
st h
ave
good
sin
e-w
ave r
esp
on
se w
ith
negli
gib
le p
ha
se d
isto
rtio
n d
ow
n t
o a
mu
ch l
ow
er
freq
uen
cy
than
th
e f
ield
fre
qu
en
cy.
In a
dd
itio
n,
to c
orr
ect
ph
ase
an
d a
mp
litu
de r
esp
on
se a
t th
e f
ield
frequ
en
cy,
it i
s n
ece
ssary
to p
rese
rve t
he d
c co
mp
on
en
t of
the b
righ
tness
sig
nal.
Th
us
a g
ood
frequ
en
cy r
esp
on
se f
rom
dc
to a
bou
t 5 M
Hz b
eco
mes
nece
ssary
for
tru
e r
ep
rod
uct
ion
of
the
bri
gh
tness
vari
ati
on
s an
d f
ind
deta
ils
of
an
y s
cen
e.
ºP
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Infl
uen
ce o
f n
um
ber
of li
nes
on
ba
nd
wid
th. A
s th
e n
um
ber
of li
nes
em
plo
yed
in
a t
ele
vis
ion
pic
ture
is
incr
ease
d,
the b
an
dw
idth
nece
ssary
for
a g
iven
qu
ali
ty o
f d
efi
nit
ion
als
o i
ncr
ease
s.
Th
is i
s d
ue t
o t
he f
act
th
at
incr
ea
sin
g t
he n
um
ber
of
lin
es
per
pic
ture
decr
ea
ses
the t
ime
du
rati
on
of
each
lin
e.
Th
is m
ean
s th
at
the s
pot
travels
acr
oss
th
e s
creen
at
a h
igh
er
velo
city
an
d r
esu
lts
in i
ncr
ease
of
the h
igh
est
mod
ula
tin
g f
requ
en
cy. F
or
exam
ple
dou
bli
ng t
he n
um
ber
of
lin
es
per
fram
e w
ou
ld v
ery
mu
ch i
mp
rove t
he v
ert
ical
reso
luti
on
, in
fact
it
wou
ld g
et
dou
ble
d
bu
t w
ou
ld n
eed
in
creasi
ng t
he b
an
dw
idth
in
th
e s
am
e r
ati
o.
If n
ow
, it
is
requ
ired
to i
ncr
ease
the h
ori
zon
tal
reso
luti
on
so t
hat
it a
gain
equ
als
th
e v
ert
ical
reso
luti
on
it
wou
ld b
e n
ece
ssary
to
scan
dou
ble
th
e n
um
ber
of
alt
ern
ate
bla
ck a
nd
wh
ite s
ign
al
ele
men
ts i
n a
lin
e, an
d t
his
wou
ld
nece
ssit
ate
mu
ltip
lyin
g t
he o
rigin
al
hig
hest
vid
eo f
requ
en
cy b
y a
fact
or
of
fou
r. T
he c
on
clu
sion
is t
hat,
if
the n
um
ber
of
lin
es
em
plo
yed
in
a t
ele
vis
ion
syst
em
is
incr
ease
d,
it i
s n
ece
ssary
to
incr
ease
th
e v
ideo f
requ
en
cy b
an
dw
idth
in
dir
ect
pro
port
ion
to t
he i
ncr
ease
in
nu
mber
of
lin
es
to m
ain
tain
th
e s
am
e d
egre
e o
f vert
ical d
efi
nit
ion
(as
befo
re),
an
d in
ord
er
to in
crease
hori
zon
tal
defi
nit
ion
in
th
e s
am
e p
rop
ort
ion
as
the i
ncr
ease
in
vert
ical
reso
luti
on
th
e v
ideo f
requ
en
cy
ban
dw
idth
mu
st i
ncr
ease
as
the s
qu
are
of
the i
ncr
ease
in
nu
mber
of
lin
es.
Eff
ect
of
inte
rla
ced
sca
nn
ing o
n b
an
dw
idth
. A
s alr
ead
y e
xp
lain
ed
, in
terl
ace
d s
can
nin
g
red
uce
s fl
ick
er.
How
ever,
sca
nn
ing 5
0 c
om
ple
te f
ram
es
of
625 l
ines
in a
pro
gre
ssiv
e m
an
ner
wou
ld a
lso e
lim
ina
te f
lick
er
in t
he p
ictu
re b
ut
this
wou
ld n
eed
dou
ble
th
e s
can
nin
g s
peed
wh
ich
in
tu
rn w
ou
ld d
ou
ble
th
e v
ideo f
requ
en
cies
corr
esp
on
din
g t
o t
he p
ictu
re e
lem
en
ts i
n a
lin
e.
Th
is w
ou
ld n
ece
ssit
ate
dou
ble
th
e c
han
nel
ban
dw
idth
of
that
requ
ired
wit
h i
nte
rlace
d
sca
nn
ing.
It s
hou
ld b
e n
ote
d t
ha
t b
y e
mp
loyin
g i
nte
rla
ced
sca
nn
ing,
the b
asi
c co
nce
pt
of
inte
rch
an
geabil
ity o
f ti
me a
nd
ban
dw
idth
is
not
vio
late
d,
beca
use
more
tim
e i
n a
llow
ed
for
tra
nsm
issi
on
an
d t
his
resu
lts
in d
ecr
ea
se o
f b
an
dw
idth
need
ed
for
ea
ch T
V c
ha
nn
el.
Th
us
inte
rlace
d s
can
nin
g r
ed
uce
s fl
ick
er
an
d c
on
serv
es
ban
dw
idth
.
Eff
ect of fi
eld
fre
qu
ency
on
ba
nd
wid
th. W
ith
in
crease
in
fie
ld fre
qu
en
cy t
he t
ime a
vail
able
for
each
fie
ld d
ecr
ease
s an
d t
his
resu
lts
in a
pro
port
ion
ate
decr
ease
of
the a
ctiv
e l
ine p
eri
od
.
���������������������������������� �!"��
ÓÔH
en
ce,
ban
dw
idth
in
crease
s in
dir
ect
pro
port
ion
to t
he i
ncr
ease
in
th
e f
ield
fre
qu
en
cy.
Ba
nd
wid
th r
equ
irem
ent
for
tra
nsm
issi
on
of
syn
chro
nis
ing p
uls
es. T
he e
qu
ali
zin
g p
uls
es
to b
e d
iscu
ssed
late
r h
ave a
pu
lse w
idth
of
2.3
µs
wit
h a
n a
llow
ed
ris
e t
ime o
f 0.2
µs.
Th
e
hig
hest
sin
uso
ida
l fr
eq
uen
cy w
hic
h m
ust
lie
in
th
e p
ass
ba
nd
of
the s
yst
em
for
eff
ect
ive
tran
smis
sion
of
these
pu
lses
is g
iven
by t
he e
xp
ress
ion
:
Hig
hest
nece
ssary
fre
qu
en
cy =
1
2×
all
ow
ed r
ise t
ime
=
10
20
2
6
×.
= 2
.5 M
Hz
It i
s th
en
cle
ar
that
all
syn
c p
uls
es
are
safe
ly p
rese
rved
in
th
e v
ideo c
ircu
itry
wh
ere
, as
has
been
sh
ow
n, a
fre
qu
en
cy b
an
dw
idth
con
sid
era
bly
in
exce
ss o
f th
is fig
ure
has
to b
e m
ain
tain
ed
in o
rder
to p
rese
rve t
he r
equ
ired
pic
ture
defi
nit
ion
.
Inte
rla
ce e
rror.
As
exp
lain
ed
earl
ier
inte
rlace
d s
can
nin
g p
rovid
es
a m
ean
s of
decr
easi
ng
the e
ffect
of
flic
ker
in t
he T
V p
ictu
re w
ith
ou
t in
creasi
ng t
he s
yst
em
ban
dw
idth
. T
he s
ele
ctio
n
of
2 : 1
as
the i
nte
rlace
rati
o i
s th
e s
imp
lest
wit
h l
east
cir
cuit
com
pli
cati
on
s. H
ere
, by s
ele
ctin
g
an
od
d n
um
ber
of
lin
es,
th
e s
ym
metr
y i
n f
ram
e b
lan
kin
g p
uls
es
is a
chie
ved
an
d t
his
en
able
s
perf
ect
in
terl
ace
d s
can
nin
g.
An
y e
rror
in s
can
nin
g t
imin
gs
an
d s
equ
en
ce w
ou
ld l
eave a
larg
e
nu
mber
of
pic
ture
ele
men
ts u
nre
solv
ed
an
d t
hu
s th
e q
uali
ty o
f th
e r
ep
rod
uce
d p
ictu
re g
ets
imp
air
ed
. F
ig.
2.9
sh
ow
s vari
ou
s ca
ses
of
inte
rlace
err
or.
For
con
ven
ien
ce o
f exp
lan
ati
on
th
e
retr
ace
tim
e h
as
been
ass
um
ed
to b
e z
ero
. In
terl
ace
err
or
occ
urs
du
e t
o t
he t
ime d
iffe
ren
ce i
n
start
ing t
he s
eco
nd
fie
ld.
For
perf
ect
in
terl
ace
th
e s
eco
nd
fie
ld s
hou
ld s
tart
fro
m p
oin
t ‘b
’ (s
ee
Fig
. 2.9
(a))
, i.
e., 3
2 µ
s aw
ay f
rom
‘a’, t
he s
tart
ing p
oin
t of
the f
irst
fie
ld. If
it
start
s earl
y o
r la
te
inte
rlace
err
or
wil
l be t
here
. F
or
a 1
6 µ
s d
ela
y i
n t
he s
tart
of
the s
eco
nd
fie
ld (
Fig
. 2.9
(b
)),
start
ing p
oin
ts o
f th
e t
wo f
ield
s w
ill
be 4
8 µ
s ap
art
in
stead
of
the d
esi
red
32 µ
s. T
hen
th
e
perc
en
tage i
nte
rlace
err
or
= 4
832
32
100
−×
= 5
0%
if t
he s
eco
nd
fie
ld s
tart
s 16 µ
s earl
y e
ven
th
en
th
e e
rror
wou
ld b
e 5
0%
. F
or
a d
ela
y o
f 32µ
s th
e
two f
ield
s w
ill
overl
ap
(F
ig. 2.9
(c)
) an
d t
he i
nte
rlace
err
or
wou
ld b
e 1
00%
, i.
e., h
alf
th
e p
ictu
re
are
a w
ill
go u
nsc
an
ned
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Th
e a
bove e
xa
mp
les
dem
on
stra
te t
ha
t in
corr
ect
sta
rt o
f a
ny f
ield
pro
du
ces
vert
ica
l
dis
pla
cem
en
t betw
een
th
e l
ines
of
the t
wo f
ield
s. T
his
bri
ngs
these
lin
es
close
r le
avin
g g
ap
s
�
�����������������������������
betw
een
th
e p
air
s th
us
form
ed
. T
he r
esu
lt i
s a d
ete
riora
tion
of
the p
ictu
re’s
vert
ical
reso
luti
on
beca
use
cert
ain
are
as
do n
ot
get
scan
ned
at
all
.
For
perf
ect
in
terl
ace
d s
can
nin
g i
t is
ess
en
tial
that
the s
tart
ing p
oin
ts a
t th
e t
op
of
the
fram
e i
s se
para
ted
exact
ly o
ne h
alf
lin
e b
etw
een
fir
st a
nd
seco
nd
fie
lds.
To a
chie
ve t
his
it
is
nece
ssary
to f
eed
tw
o r
egu
larl
y s
pace
d s
yn
chro
nis
ing p
uls
es
to t
he f
ield
tim
e b
ase
du
rin
g e
ach
fram
e p
eri
od
. O
ne o
f th
ese
pu
lses
mu
st a
rriv
e i
n t
he m
idd
le o
f a l
ine a
nd
th
e n
ext
at
the e
nd
of
a l
ine.
Th
is i
s sh
ow
n i
n F
ig.
2.1
0.
Th
us
the v
ert
ical
tim
e b
ase
mu
st b
e t
riggere
d 5
0 t
imes
per
seco
nd
in
th
e m
an
ner
exp
lain
ed
above. F
or
half
lin
e s
ep
ara
tion
betw
een
th
e t
wo f
ield
s on
ly t
he
top
most
an
d t
he e
xtr
em
e b
ott
om
lin
es
are
th
en
half
lin
es
wh
ere
as
the r
em
ain
ing l
ines
are
all
full
lin
es.
If
there
are
x n
um
ber
of
full
lin
es
per
field
, w
here
x m
ay b
e e
ven
or
od
d,
the t
ota
l
nu
mber
of
full
lin
es
per
fram
e i
s th
en
2x, an
even
nu
mber.
To t
his
, w
hen
th
e t
wo h
alf
lin
es
get
ad
ded
th
e t
ota
l n
um
ber
of
lin
es
per
fram
e b
eco
mes
od
d. T
hu
s fo
r in
terl
ace
d s
can
nin
g t
he t
ota
l
nu
mber
of
lin
es
in a
ny T
V s
yst
em
mu
st b
e o
dd
. W
ith
an
even
nu
mber
of
lin
es
the t
wo f
ield
s are
bou
nd
to f
all
on
each
oth
er
an
d i
nte
rlace
d s
can
nin
g w
ou
ld n
ot
tak
e p
lace
.
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Fu
rth
er
for
corr
ect
in
terl
aci
ng i
t beco
mes
nece
ssary
th
at
at
the t
ran
smit
ter
au
tom
ati
c
frequ
en
cy c
on
trol
mu
st b
e u
tili
zed
to m
ain
tain
a h
ori
zon
tal
scan
nin
g f
requ
en
cy t
hat
is e
xact
ly
312.5
tim
es
as
gre
at
as
the f
ield
fre
qu
en
cy,
i.e.
, 50 H
z.
Th
is i
s acc
om
pli
shed
by g
en
era
tin
g a
stable
fre
qu
en
cy a
t 15625 H
z b
y c
ryst
al
con
troll
ed
osc
illa
tor
circ
uit
s. A
fre
qu
en
cy d
ou
bli
ng
circ
uit
pro
du
ces
a f
requ
en
cy o
f 31250 H
z,
wh
ich
is
uti
lized
to c
on
trol
the c
orr
ect
gen
era
tion
of
equ
ali
zin
g a
nd
vert
ical
syn
c p
uls
es.
Fou
r fr
equ
en
cy d
ivis
ion
cir
cuit
s each
wit
h a
rati
o o
f 5 :
1
are
em
plo
yed
to d
eri
ve 5
0 H
z, th
e v
ert
ical sc
an
nin
g f
requ
en
cy (
31250 =
5 ×
5 ×
5 ×
5 ×
50).
Th
us
all
th
e r
equ
ired
fre
qu
en
cies
are
deri
ved
fro
m a
com
mon
sta
ble
sou
rce a
nd
th
ey a
uto
mati
call
y
rem
ain
in
terl
ock
ed
in
th
e c
orr
ect
ra
tios.
To a
chie
ve t
his
, i.
e.,
freq
uen
cy d
ivis
ion
, th
e t
ota
l
nu
mber
of
lin
es
per
fram
e m
ust
be a
pro
du
ct o
f sm
all
wh
ole
nu
mbers
. T
he f
ram
e f
requ
en
cy o
f
625 s
ati
sfie
s all
th
e a
bove r
equ
irem
en
ts.
Sim
ilarl
y 5
25 l
ines
in t
he A
meri
can
syst
em
an
d 8
19
lin
es
in t
he F
ren
ch s
yst
em
als
o m
eet
these
requ
irem
en
ts.
����8�������8��������9����������:�������
;C
om
pa
riso
n o
f va
riou
s T
V s
yst
ems.
Pic
ture
an
d s
ou
nd
sig
nal
stan
dard
s fo
r th
e p
rin
cip
al
mon
och
rom
e t
ele
vis
ion
syst
em
s are
giv
en
at
the e
nd
of ch
ap
ter
4. T
he C
CIR
625-B
mon
och
rom
e
syst
em
use
d i
n m
ost
part
s of
Eu
rop
e a
nd
ad
op
ted
by I
nd
ia h
as
a v
ideo b
an
dw
idth
of
5 M
Hz,
wh
ere
as
the B
riti
sh 6
25 l
ine s
yst
em
has
a v
ideo b
an
dw
idth
of
5.5
MH
z.
Obvio
usl
y,
here
0.7
3
has
been
use
d a
s th
e r
eso
luti
on
fact
or
inst
ead
of
the 0
.69 u
sed
in
ou
r sy
stem
. S
o t
he B
riti
sh
syst
em
is
marg
inall
y b
ett
er
than
th
e E
uro
pean
syst
em
. T
he F
ren
ch T
V s
yst
em
em
plo
ys
819
lin
es
wit
h a
vid
eo b
an
dw
idth
of
10.4
MH
z.
Th
is s
yst
em
th
ere
fore
has
both
mu
ch i
mp
roved
vert
ical
reso
luti
on
an
d a
bett
er
hori
zon
tal
reso
luti
on
.
Th
e A
meri
can
525 l
ine s
yst
em
em
plo
ys
a f
ram
e f
requ
en
cy o
f 30 a
s co
mp
are
d t
o 2
5 i
n t
he
CC
IR 6
25
-B m
on
och
rom
e s
yst
em
. T
hu
s, t
he l
ine f
req
uen
cy i
n t
his
syst
em
is
15
75
0,
wh
ich
com
pare
s very
clo
sely
to o
ur
syst
em
wh
ere
th
e lin
e f
requ
en
cy is
15625. H
ow
ever,
th
e A
meri
can
syst
em
em
plo
ys
a b
an
dw
idth
of
4 M
Hz w
hic
h s
uggest
s th
at
the h
ori
zon
tal
reso
luti
on
of
this
syst
em
is
less
th
an
all
oth
er
syst
em
s in
use
. It
mu
st b
e n
ote
d t
hat
the n
um
ber
of li
nes
em
plo
yed
by a
giv
en
TV
syst
em
is
not
in i
tself
, a g
uid
e t
o t
he q
uali
ty o
f re
solu
tion
avail
able
fro
m t
he
syst
em
. It
is
tru
e t
hat
gre
ate
r th
e n
um
ber
of
lin
es
the b
ett
er
the v
ert
ical
reso
luti
on
, bu
t an
ass
ess
men
t of
the h
ori
zon
tal
reso
luti
on
, i.
e., th
e b
an
dw
idth
em
plo
yed
by t
he s
yst
em
is
a b
ett
er
overa
ll g
uid
e t
o t
he q
uali
ty o
f d
efi
nit
ion
.
< =>?@ABCDEBFB?G@A
In a
dd
itio
n t
o p
rop
er
ban
dw
idth
requ
ired
to p
rod
uce
th
e d
eta
ils
all
ow
ed
by t
he s
can
nin
g s
yst
em
at
the t
ran
smit
tin
g e
nd
an
d t
he p
ictu
re t
ube a
t th
e r
ece
ivin
g e
nd
, th
e s
ign
al-
tran
smis
sion
syst
em
sh
ou
ld h
ave p
rop
er
tran
sfer
chara
cteri
stic
s to
pre
serv
e s
am
e b
righ
tness
gra
dati
on
as
the e
ye w
ou
ld p
erc
eiv
e w
hen
vie
win
g t
he s
cen
e d
irect
ly.
An
y n
on
-lin
eari
ty i
n t
he p
ick
-up
an
d
pic
ture
tu
be s
hou
ld a
lso b
e c
orr
ect
ed
by p
rovid
ing in
vers
e n
on
lin
eari
ties
in t
he c
han
nel ci
rcu
itry
to o
bta
in o
vera
ll l
inear
chara
cteri
stic
s. N
ote
th
at
the s
en
sati
on
in
th
e e
ye t
o d
ete
ct c
han
ges
or
bri
gh
tness
is
logari
thm
ic i
n n
atu
re a
nd
th
is m
ust
be t
ak
en
in
to a
ccou
nt
wh
ile d
esi
gn
ing t
he
overa
ll c
han
nel.
Vari
ou
s oth
er
fact
ors
th
at
infl
uen
ce t
he t
on
al
qu
ali
ty o
f th
e r
ep
rod
uce
d p
ictu
re a
re :
(a)
Con
tra
st.
Th
is i
s th
e d
iffe
ren
ce i
n i
nte
nsi
ty b
etw
een
bla
ck a
nd
wh
ite p
art
s of
the
pic
ture
over
an
d a
bove t
he b
righ
tness
level.
(b)
Con
tra
st r
ati
o. T
he r
ati
o o
f m
axim
um
to m
inim
um
bri
gh
tness
rela
tive t
o t
he o
rigin
al
pic
ture
is
call
ed
con
trast
rati
o.
In b
road
dayli
gh
t th
e v
ari
ati
on
s in
bri
gh
tness
are
very
wid
e
wit
h r
ati
o a
s h
igh
as
10000 : 1
, w
here
as
the p
ictu
re t
ube, beca
use
of
cert
ain
lim
itati
on
s, c
an
not
pro
du
ce a
con
trast
wit
h v
ari
ati
on
s m
ore
th
an
50 :
1 o
r atm
ost
100 :
1.
Rati
o o
f bri
gh
tness
vari
ati
on
s in
th
e r
ep
rod
uce
d p
ictu
re o
n t
he s
creen
of th
e p
ictu
re t
ube, t
o t
he b
righ
tness
vari
ati
on
s
in t
he o
rigin
al
scen
e i
s k
now
n a
s G
am
ma o
f th
e p
ictu
re.
Its
valu
e i
s cl
ose
to 0
.5.
In s
tud
ios,
un
der
con
troll
ed
con
dit
ion
s of
ligh
t, t
he v
ari
ati
on
s a
re l
ess
wid
e t
ha
n o
uts
ide a
nd
so t
he
bri
gh
tness
vari
ati
on
s th
at
can
be r
ep
rod
uce
d b
y t
he p
ictu
re t
ube a
re n
ot
very
mu
ch d
iffe
ren
t
than
th
at
of
the s
cen
e. R
eali
sm i
s st
ill
main
tain
ed
beca
use
th
e v
iew
er
does
not
act
uall
y s
ee t
he
sce
ne b
ein
g t
ele
vis
ed
. A
noth
er
fact
or
wh
ich
ma
kes s
trin
gen
t d
em
an
ds f
rom
th
e s
yste
m
un
nece
ssary
is
the f
act
th
at
ou
r eye c
an
acc
om
mod
ate
not
more
th
an
10 :
1 v
ari
ati
on
s of
ligh
t
inte
nsi
ty a
t an
y t
ime.
Too b
righ
t a r
ep
rese
nta
tion
of
the b
righ
t are
as
in a
pic
ture
wou
ld m
ak
e
Ó
�����������������������������
gre
y a
rea
s a
pp
ea
r a
s d
ark
in
com
pa
riso
n.
Th
is i
s tr
ue a
t a
ll l
evels
of
ligh
t in
ten
sity
wit
h
bri
gh
tness
vari
ati
on
s in
rela
tive r
ati
os
of
10 :
1.
Wh
en
a T
V r
ece
iver
is o
ff,
there
is
no b
eam
imp
ingin
g o
n t
he f
luore
scen
t sc
reen
of
the p
ictu
re t
ube a
nd
no l
igh
t gets
em
itte
d.
Th
en
wit
h
norm
al
ligh
t in
th
e r
oom
th
e s
creen
ap
pears
as
du
ll w
hit
e.
Bu
t w
hen
th
e r
ece
iver
is n
o,
an
d a
TV
pro
gra
mm
e i
s bein
g r
ece
ived
th
e b
righ
t p
ort
ion
s of
the s
cen
e a
pp
ear
qu
ite b
righ
t beca
use
the c
orr
esp
on
din
g a
mp
litu
de o
f th
e v
ideo s
ign
al
mak
es
the c
on
trol-
gri
d o
f th
e p
ictu
re t
ube
mu
ch less
negati
ve a
nd
th
e c
on
sequ
en
t in
crease
d b
eam
cu
rren
t ca
use
s m
ore
lig
ht
on
th
e s
creen
.
How
ever,
for
a v
ery
dark
port
ion
of
the s
cen
e t
he c
orr
esp
on
din
g v
ideo s
ign
al
mak
es
the g
rid
hig
hly
negati
ve w
ith
resp
ect
to t
he c
ath
od
e a
nd
th
us
cuts
-off
th
e b
eam
cu
rren
t an
d n
o l
igh
t is
em
itte
d o
n t
he c
orr
esp
on
din
g p
ort
ion
s on
th
e s
creen
. T
hese
are
as
ap
pear
to t
he e
ye a
s d
ark
in
com
pari
son
wit
h t
he h
igh
lig
ht
are
as
of
the s
creen
, w
here
as
the s
am
e a
rea i
n t
he a
bse
nce
of
beam
cu
rren
t w
hen
th
e s
et
was
off
ap
peare
d c
lose
to a
wh
ite s
had
e. T
his
as
exp
lain
ed
earl
ier
is
du
e t
o t
he logari
thm
ic r
esp
on
se o
f th
e h
um
an
eye a
nd
its
in
abil
ity t
o a
ccom
mod
ate
lig
ht
inte
nsi
ty
vari
ati
on
s gre
ate
r th
an
10 :
1.
(c)
Vie
win
g d
ista
nce
. T
he v
iew
ing d
ista
nce
fro
m t
he s
creen
of
the T
V r
ece
iver
shou
ld n
ot
be s
o l
arg
e t
hat
the e
ye c
an
not
reso
lve d
eta
ils
of
the p
ictu
re. T
he d
ista
nce
sh
ou
ld a
lso n
ot
be s
o
small
th
at
pic
ture
ele
men
ts b
eco
me s
ep
ara
tely
vis
ible
. T
he a
bove c
on
dit
ion
s are
met
wh
en
th
e
vert
ica
l p
ictu
re s
ize s
ub
ten
ds
an
an
gle
of
ap
pro
xim
ate
ly 1
5°
at
the e
ye.
Th
e d
ista
nce
als
o
dep
en
ds
on
ha
bit
, va
ries
from
pers
on
to p
ers
on
, a
nd
lie
s b
etw
een
3 t
o 8
tim
es
the p
ictu
re
heig
ht.
Most
peop
le p
refe
r a d
ista
nce
clo
se t
o f
ive t
imes
the p
ictu
re h
eig
ht.
Wh
ile v
iew
ing T
V,
a s
mall
lig
ht
shou
ld b
e k
ep
t on
in
th
e r
oom
to r
ed
uce
con
trast
. T
his
does
not
stra
in t
he e
yes
an
d t
here
is
less
fati
gu
e. E H IJ H KL MHNOJ PQN
1.
Ju
stif
y t
he c
hoic
e o
f re
cta
ngu
lar
fra
me w
ith
wid
th t
o h
eig
ht
rati
o =
4/3
for
tele
vis
ion
tra
nsm
is-
sion
an
d r
ece
pti
on
.
2.
How
is
the i
llu
sion
of
con
tin
uit
y c
rea
ted
in
tele
vis
ion
pic
ture
s ?
Wh
y h
as
the f
ram
e r
ece
pti
on
rate
been
ch
ose
n t
o b
e 2
5 a
nd
not
24
as
in m
oti
on
pic
ture
s ?
3.
Wh
at
do y
ou
un
ders
tan
d b
y i
nte
rla
ced
sca
nn
ing ?
Sh
ow
th
at
it r
ed
uce
s fl
ick
er
an
d c
on
serv
e
ba
nd
wid
th.
4.
Wh
at
do y
ou
un
ders
tan
d b
y a
ctiv
e a
nd
bla
nk
ing p
eri
od
s in
h
ori
zon
tal
an
d v
ert
ica
l sc
an
nin
g ?
Giv
e t
he p
eri
od
s of
nom
ina
l, a
ctiv
e a
nd
retr
ace
in
terv
als
of
hori
zon
tal
an
d v
ert
ica
l sc
an
nin
g a
s
use
d i
n t
he 6
25 l
ine s
yst
em
.
5.
How
ma
ny h
ori
zon
tal
lin
es
get
tra
ced
du
rin
g e
ach
vert
ica
l re
tra
ce ?
Wh
at
is t
he a
ctiv
e n
um
ber
of
lin
es
tha
t a
re a
ctu
all
y u
sed
for
pic
ture
in
form
ati
on
pic
k u
p a
nd
rece
pti
on
?
6.
Dra
w a
pic
ture
fra
me c
ha
rt s
how
ing t
he t
ota
l n
um
ber
of
act
ive a
nd
in
act
ive l
ines
du
rin
g e
ach
field
an
d e
sta
bli
sh t
he n
eed
for
term
ina
tin
g t
he f
irst
fie
ld i
n a
ha
lf l
ine a
nd
th
e b
egin
nin
g t
he
seco
nd
at
the m
idd
le o
f a
lin
e a
t th
e t
op
.
7.
Ju
stif
y t
he c
hoic
e o
f 6
25
lin
es
for
TV
tra
nsm
issi
on
. W
hy i
s th
e t
ota
l n
um
ber
of
lin
es
kep
t od
d i
n
all
tele
vis
ion
syst
em
s ?
Wh
at
is t
he s
ign
ific
an
ce o
f ch
oosi
ng t
he n
um
ber
of
lin
es
as
62
5 a
nd
not
623 o
r 627 ?
8.
Wh
at
do y
ou
un
ders
tan
d b
y r
eso
luti
on
or
Kell
-fa
ctor
? H
ow
does
it a
ffect
th
e v
ert
ica
l re
solu
tion
of
a t
ele
vis
ion
pic
ture
? S
how
th
at
the v
ert
ica
l re
solu
tion
in
crea
ses
wit
h i
ncr
ea
se i
n n
um
ber
of
scan
nin
g l
ines.
����8�������8��������9����������:�������
9
.W
ha
t is
mea
nt
by e
qu
al
vert
ica
l a
nd
hori
zon
tal
‘reso
luti
on
?’ D
eri
ve a
n e
xp
ress
ion
for
the h
igh
-
est
mod
ula
tin
g f
req
uen
cy i
n a
tele
vis
ion
syst
em
an
d s
how
th
at
it i
s n
ea
rly 5
MH
z.
in t
he 6
25
-B
mon
och
rom
e s
yst
em
.
10
.S
how
th
at
if t
he n
um
ber
of
lin
es
em
plo
yed
in
a T
V s
yst
em
is
incr
ea
sed
th
en
th
e h
igh
est
vid
eo
freq
uen
cy m
ust
in
crea
se a
s th
e s
qu
are
of
the i
ncr
ease
in
nu
mb
er
of
lin
es
for
eq
ua
l im
pro
vem
en
t
in v
ert
ica
l a
nd
hori
zon
tal
reso
luti
on
.
11
.S
how
th
at
the 6
25
-B T
V s
yst
em
is
on
ly m
arg
ina
lly s
up
eri
or
to t
he 5
25
lin
e A
meri
can
syst
em
.
12
.W
ha
t d
o y
ou
un
ders
tan
d b
y i
nte
rla
ce e
rror
an
d h
ow
does
it a
ffect
th
e q
ua
lity
of
the p
ictu
re ?
Ca
lcu
late
th
e p
erc
en
tage i
nte
rla
ce e
rror
wh
en
th
e s
eco
nd
fie
ld i
s d
ela
yed
by 8
µs.
Retr
ace
tim
e
may b
e a
ssu
med
to b
e n
egli
gib
le.
13
.In
th
e B
riti
sh 6
25
lin
es
syst
em
th
e r
eso
luti
on
fa
ctor
em
plo
yed
is
0.7
3 i
nst
ea
d o
f 0
.69
as
use
d i
n
the 6
25
-B m
on
och
rom
e s
yst
em
. A
ll o
ther
sca
nn
ing d
eta
ils
rem
ain
ing t
he s
am
e,
calc
ula
te t
he
hig
hest
mod
ula
tin
g f
req
uen
cy u
sed
in
th
e B
riti
sh s
yst
em
.
14
.E
xp
lain
th
e n
eed
for
pro
vid
ing v
ery
good
low
fre
qu
en
cy r
esp
on
se a
nd
ph
ase
ch
ara
cteri
stic
s in
am
pli
fiers
use
d i
n a
ny T
V l
ink
, fo
r p
rop
er
rep
rod
uct
ion
of
bri
gh
tness
va
ria
tion
s.
15
.T
he r
ele
va
nt
da
ta f
or
a c
lose
d c
ircu
it T
V s
yst
em
is
giv
en
belo
w.
Ca
lcu
late
th
e h
igh
est
mod
ula
t-
ing f
req
uen
cy t
ha
t w
ill
be g
en
era
ted
wh
ile s
can
nin
g t
he m
ost
str
ingen
t ca
se o
f a
ltern
ate
bla
ck
an
d w
hit
e d
ots
for
eq
ua
l vert
ica
l a
nd
hori
zon
tal
reso
luti
on
.
No.
of
lin
es
= 2
50
Inte
rla
ce r
ati
o=
1 :
1
Pic
ture
rep
eti
tion
ra
te=
50
/sec
Asp
ect
ra
tio
= 4
/3
Vert
ica
l re
tra
ce t
ime
= 1
0%
of
the p
ictu
re f
ram
e t
ime
Hori
zon
tal
retr
ace
tim
e=
20
% o
f th
e t
ota
l li
ne t
ime
Ass
um
e r
eso
luti
on
fa
ctor
= 0
.8
An
s≈ 2
MH
z
16
.E
xp
lain
th
e m
ea
nin
g o
f te
rms-
ton
al
gra
da
tion
, co
ntr
ast
, co
ntr
ast
ra
tio a
nd
ga
mm
a o
f th
e p
ic-
ture
.
Wh
en
a T
V r
ece
iver
is o
ff,
no e
lect
ron
bea
m s
trik
es
the p
ictu
re t
ub
e s
creen
an
d t
he s
creen
fa
ce
look
s a
du
ll w
hit
e.
Wit
h t
he s
et
on
an
d a
bla
ck a
nd
wh
ite p
ictu
re s
how
ing o
n t
he s
creen
, n
o
ele
ctro
n b
ea
m i
mp
inges
on
th
e d
ark
er
are
a o
f th
e r
ep
rod
uce
d p
ictu
re.
Bu
t th
ese
are
as
now
ap
-
pea
r q
uit
e b
lack
in
stea
d o
f th
e d
ull
wh
ite o
f th
e s
wit
ched
-off
set.
Exp
lain
th
e r
ea
son
for
this
dif
fere
nce
in
ap
pea
ran
ce.
Com
posit
e Vi
deo
Sign
alC
om
posit
e v
ideo s
ign
al
con
sis
ts o
f a
ca
mera
sig
na
l co
rresp
on
din
g t
o t
he d
esir
ed
pic
ture
info
rma
tion
, b
lan
kin
g p
uls
es t
o m
ak
e t
he r
etr
ace
in
vis
ible
, a
nd
syn
chro
niz
ing p
uls
es t
o
syn
chro
niz
e t
he t
ran
smit
ter
an
d r
ece
iver
scan
nin
g.
A h
ori
zon
tal
syn
chro
niz
ing (
syn
c) p
uls
e i
s
need
ed
at
the e
nd
of
each
act
ive lin
e p
eri
od
wh
ere
as
a v
ert
ical sy
nc
pu
lse is
requ
ired
aft
er
each
field
is
scan
ned
. T
he a
mp
litu
de o
f both
hori
zon
tal
an
d v
ert
ical
syn
c p
uls
es
is k
ep
t th
e s
am
e t
o
obta
in h
igh
er
eff
icie
ncy
of
pic
ture
sig
nal
tran
smis
sion
bu
t th
eir
du
rati
on
(w
idth
) is
ch
ose
n t
o
be d
iffe
ren
t fo
r se
para
tin
g t
hem
at
the r
ece
iver.
Sin
ce s
yn
c p
uls
es
are
need
ed
con
secu
tively
an
d n
ot
sim
ult
an
eou
sly w
ith
th
e p
ictu
re s
ign
al,
th
ese
are
sen
t on
a t
ime d
ivis
ion
basi
s an
d
thu
s fo
rm a
part
of
the c
om
posi
te v
ideo s
ign
al.
R =STGFU@VGDABCFGWUAVG@AV
Fig
ure
3.1
sh
ow
s th
e c
om
posi
te v
ideo s
ign
al
deta
ils
of
thre
e d
iffe
ren
t li
nes
each
corr
esp
on
din
g
to a
dif
fere
nt
bri
gh
tness
level
of
the s
cen
e. A
s il
lust
rate
d t
here
, th
e v
ideo s
ign
al
is c
on
stra
ined
to v
ary
betw
een
cert
ain
am
pli
tud
e l
imit
s. T
he l
evel
of
the v
ideo s
ign
al
wh
en
th
e p
ictu
re d
eta
il
bein
g t
ran
smit
ted
corr
esp
on
ds
to t
he m
axim
um
wh
iten
ess
to b
e h
an
dle
d,
is r
efe
rred
to a
s
peak
-wh
ite l
evel.
Th
is i
s fi
xed
at
10 t
o 1
2.5
perc
en
t of
the m
axim
um
valu
e o
f th
e s
ign
al
wh
ile
the b
lack
level co
rresp
on
ds
to a
pp
roxim
ate
ly 7
2 p
erc
en
t. T
he s
yn
c p
uls
es
are
ad
ded
at
75
perc
en
t
level
call
ed
th
e b
lan
kin
g l
evel.
Th
e d
iffe
ren
ce b
etw
een
th
e b
lack
level
an
d b
lan
kin
g l
evel
is
kn
ow
n a
s th
e ‘P
ed
est
al’. H
ow
ever,
in
act
ual
pra
ctic
e, th
ese
tw
o l
evels
, bein
g v
ery
clo
se, te
nd
to
merg
e w
ith
each
oth
er
as
show
n i
n t
he f
igu
re. T
hu
s th
e p
ictu
re i
nfo
rmati
on
may v
ary
betw
een
10 p
erc
en
t to
abou
t 75 p
erc
en
t of th
e c
om
posi
te v
ideo s
ign
al d
ep
en
din
g o
n t
he r
ela
tive b
righ
tness
of
the p
ictu
re a
t an
y i
nst
an
t. T
he d
ark
er
the p
ictu
re t
he h
igh
er
wil
l be t
he v
olt
age w
ith
in t
hose
lim
its.
Note
th
at
the l
ow
est
10 p
erc
en
t of
the v
olt
age r
an
ge (
wh
iter
than
wh
ite r
an
ge)
is n
ot
use
d t
o m
inim
ize n
ois
e e
ffect
s. T
his
als
o e
nsu
res
en
ou
gh
marg
in f
or
exce
ssiv
e b
righ
t sp
ots
to
be a
ccom
mod
ate
d w
ith
ou
t ca
usi
ng a
mp
litu
de d
isto
rtio
n a
t th
e m
od
ula
tor.
At
the r
ece
iver
the p
ictu
re t
ub
e i
s b
iased
to e
nsu
re t
ha
t a
rece
ived
vid
eo v
olt
age
corr
esp
on
din
g t
o a
bou
t 10 p
erc
en
t m
od
ula
tion
yie
lds
com
ple
te w
hit
en
ess
at
that
part
icu
lar
poin
t on
th
e s
creen
, an
d a
n a
nalo
gou
s arr
an
gem
en
t is
mad
e f
or
the b
lack
level.
Besi
des
this
,
the t
ele
vis
ion
rece
ivers
are
pro
vid
ed
wit
h ‘
bri
gh
tness
’ a
nd
‘co
ntr
ast
’ co
ntr
ols
to e
na
ble
th
e
vie
wer
to m
ak
e f
inal
ad
just
men
ts a
s h
e t
hin
ks
fit.
D.C
. co
mp
on
ent
of
the
vid
eo s
ign
al.
In
ad
dit
ion
to c
on
tin
uou
s am
pli
tud
e v
ari
ati
on
s fo
r
ind
ivid
ua
l p
ictu
re e
lem
en
ts,
the v
ideo s
ign
al
ha
s a
n a
vera
ge v
alu
e o
r d
c c
om
pon
en
t
X3Co
mpo
site
Vide
o Si
gnal
���:������������Y���
Z
corr
esp
on
din
g t
o t
he a
vera
ge b
righ
tness
of
the s
cen
e.
In t
he a
bse
nce
of
dc
com
pon
en
t th
e
rece
iver
can
not
foll
ow
ch
an
ges
in b
righ
tness
, as
the a
c ca
mera
sig
nal,
say f
or
gre
y p
ictu
re
ele
men
ts o
n a
bla
ck b
ack
gro
un
d w
ill
then
be t
he s
am
e a
s a s
ign
al
for
wh
ite a
rea o
n a
gre
y
back
-gro
un
d. In
Fig
. 3.1
, d
c co
mp
on
en
ts o
f th
e s
ign
al
for
thre
e l
ines
have b
een
id
en
tifi
ed
, each
rep
rese
nti
ng a
dif
fere
nt
level
of
avera
ge b
righ
tness
in
th
e s
cen
e.
It m
ay b
e n
ote
d t
hat
the
bre
ak
sh
ow
n i
n t
he i
llu
stra
tion
aft
er
each
lin
e s
ign
al
is t
o e
mp
hasi
ze t
hat
dc
com
pon
en
t of
the
vid
eo s
ign
al
is t
he a
vera
ge v
alu
e f
or
com
ple
te f
ram
es
rath
er
than
lin
es
sin
ce t
he b
ack
gro
un
d
info
rmati
on
of
the p
ictu
re i
nd
icate
s th
e b
righ
tness
of
the s
cen
e.
Th
us
Fig
. 3.1
ill
ust
rate
s th
e
con
cep
t of
chan
ge in
th
e a
vera
ge b
righ
tness
of
the s
cen
e w
ith
th
e h
elp
of
thre
e lin
es
in s
ep
ara
te
fram
es
beca
use
th
e a
vera
ge b
righ
tness
can
ch
an
ge o
nly
fro
m f
ram
e t
o f
ram
e a
nd
not
from
lin
e
to l
ine.
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edes
tal
hei
gh
t. A
s n
ote
d i
n F
ig.
3.1
th
e p
ed
est
al
heig
ht
is t
he d
ista
nce
betw
een
th
e
ped
est
al
level
an
d t
he a
vera
ge v
alu
e (
dc
level)
axis
of
the v
ideo s
ign
al.
Th
is i
nd
icate
s avera
ge
bri
gh
tness
sin
ce i
t m
easu
res
how
mu
ch t
he a
vera
ge v
alu
e d
iffe
rs f
rom
th
e b
lack
level.
Even
wh
en
th
e s
ign
al lo
ses
its
dc
valu
e w
hen
pass
ed
th
rou
gh
a c
ap
aci
tor-
cou
ple
d c
ircu
it t
he d
ista
nce
betw
een
th
e p
ed
est
al
an
d t
he d
c le
vel
stays
the s
am
e a
nd
th
us
it i
s co
nven
ien
t to
use
th
e
ped
est
al
level
as
the r
efe
ren
ce l
evel
to i
nd
icate
avera
ge b
righ
tness
of
the s
cen
e.
Set
tin
g th
e p
edes
tal le
vel
. Th
e o
utp
ut
sign
al fr
om
th
e T
V c
am
era
is
of very
sm
all
am
pli
tud
e
an
d i
s p
ass
ed
th
rou
gh
severa
l st
ages
of
ac
cou
ple
d h
igh
gain
am
pli
fiers
befo
re b
ein
g c
ou
ple
d t
o
a c
on
trol
am
pli
fier.
Here
syn
c p
uls
es
an
d b
lan
kin
g p
uls
es
are
ad
ded
an
d t
hen
cli
pp
ed
at
the
corr
ect
level to
form
th
e p
ed
est
als
. S
ince
th
e p
ed
est
al h
eig
ht
dete
rmin
es
the a
vera
ge b
righ
tness
of
the s
cen
e,
an
y s
mall
er
valu
e t
han
th
e c
orr
ect
on
e w
ill
mak
e t
he s
cen
e d
ark
er
wh
ile a
larg
er
ped
est
al h
eig
ht
wil
l re
sult
in
hig
her
avera
ge b
righ
tness
. Th
e v
ideo c
on
trol op
era
tor
wh
o o
bse
rves
the s
cen
e a
t th
e s
tud
io s
ets
th
e level fo
r th
e d
esi
red
bri
gh
tness
in
th
e r
ep
rod
uce
d p
ictu
re w
hic
h
�����������������������������
he i
s vie
win
g o
n a
mon
itor
rece
iver.
Th
is i
s k
now
n a
s d
c in
sert
ion
beca
use
th
is a
mou
nts
to
ad
din
g a
dc
com
pon
en
t to
th
e a
c si
gn
al.
On
ce t
he d
c in
sert
ion
has
been
aco
mp
lish
ed
th
e p
ed
est
al
level
beco
mes
the b
lack
refe
ren
ce a
nd
th
e p
ed
est
al
heig
ht
ind
icate
s co
rrect
rela
tive b
righ
tness
for
the r
ep
rod
uce
d p
ictu
re.
How
ever,
th
e d
c le
vel
inse
rted
in
th
e c
on
trol
am
pli
fier
is u
suall
y
lost
in
su
cceed
ing s
tages
beca
use
of
cap
aci
tive c
ou
pli
ng, bu
t st
ill
the c
orr
ect
dc
com
pon
en
t ca
n
be r
ein
sert
ed
wh
en
nece
ssary
beca
use
th
e p
ed
est
al
heig
ht
rem
ain
s th
e s
am
e.
Th
e bla
nkin
g p
uls
es.
Th
e c
om
posi
te v
ideo s
ign
al
con
tain
s bla
nk
ing p
uls
es
to m
ak
e t
he
retr
ace
lin
es
invis
ible
by r
ais
ing t
he s
ign
al
am
pli
tud
e s
ligh
tly a
bove t
he b
lack
level
(75 p
er
cen
t) d
uri
ng t
he t
ime t
he s
can
nin
g c
ircu
its
pro
du
ce r
etr
ace
s. A
s il
lust
rate
d i
n F
ig.
3.2
, th
e
com
posit
e v
ideo s
ign
al
con
tain
s h
oriz
on
tal
an
d v
erti
ca
l b
lan
kin
g p
uls
es t
o b
lan
k t
he
corr
esp
on
din
g r
etr
ace
in
terv
als
. T
he r
ep
eti
tion
rate
of
hori
zon
tal
bla
nk
ing p
uls
es
is t
here
fore
equ
al to
th
e lin
e s
can
nin
g fre
qu
en
cy o
f 15625 H
z. S
imil
arl
y t
he fre
qu
en
cy o
f th
e v
ert
ical bla
nk
ing
pu
lses
is e
qu
al
to t
he f
ield
-sca
nn
ing f
requ
en
cy o
f 50 H
z.
It m
ay b
e n
ote
d t
hat
thou
gh
th
e l
evel
of
the b
lan
kin
g p
uls
es
is d
isti
nct
ly a
bove t
he p
ictu
re s
ign
al
info
rmati
on
, th
ese
are
not
use
d a
s
syn
c p
uls
es.
Th
e r
easo
n is
that
an
y o
ccasi
on
al si
gn
al co
rresp
on
din
g t
o a
ny e
xtr
em
e b
lack
port
ion
in t
he p
ictu
re m
ay r
ise a
bove t
he b
lan
kin
g l
evel
an
d m
igh
t co
nce
iva
bly
in
terf
ere
wit
h t
he
syn
chro
niz
ati
on
of
the s
can
nin
g g
en
era
tors
. T
here
fore
, th
e s
yn
c p
uls
es,
sp
eci
all
y d
esi
gn
ed
for
trig
geri
ng t
he s
weep
osc
illa
tors
are
pla
ced
in
th
e u
pp
er
25 p
er
cen
t (7
5 p
er
cen
t to
100 p
er
cen
t
of
the c
arr
ier
am
pli
tud
e)
of
the v
ideo s
ign
al,
an
d a
re t
ran
smit
ted
alo
ng w
ith
th
e p
ictu
re s
ign
al.
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m Ë ÌÍÎ ×± «Ñ¬ ÑØ ÒÓ± Ϫϻ³ Ï Ù ªÍ° Ê«±×± «Ñ¬ ÑØÒÓ± ϪҪͯ ÌÔ ÕÚ ÌÒ¯ Ê° Óͪ¯ ÑÛ ÌÍÜ«° ÌÑ Ô Óͯ ÑØ°® ϯ Ñ° ªÍ²«±Ö
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ùú û ü� üýÝ ��ú Þ��� �5 ¡��ú ����� �ßú û� 2� ���ú ¡ú5 ���ú û�� ü¥ ��� 2� �������55 �5 �� � ¡�
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Syn
c p
uls
e a
nd
vid
eo s
ign
al
am
pli
tud
e ra
tio.
Th
e o
vera
ll a
rran
gem
en
t of
com
bin
ing t
he
pic
ture
sig
nal
an
d s
yn
c p
uls
es
may b
e t
hou
gh
t of
as
a k
ind
of
volt
age d
ivis
ion
mu
ltip
lexin
g
wh
ere
abou
t 65 p
er
cen
t of
the c
arr
ier
am
pli
tud
e i
s occ
up
ied
by t
he v
ideo s
ign
al
an
d t
he u
pp
er
���:������������Y���
Ô
25 p
er
cen
t by t
he s
yn
c p
uls
es.
Th
us,
as
show
n i
n F
ig.
3.1
, th
e f
inal
rad
iate
d s
ign
al
has
a
pic
ture
to s
yn
c si
gn
al
rati
o (
P/S
) equ
al
to 1
0/4
. T
his
rati
o h
as
been
fou
nd
most
sati
sfact
ory
beca
use
if
the p
ictu
re s
ign
al
am
pli
tud
e i
s in
crease
d a
t th
e e
xp
en
se o
f sy
nc
pu
lses,
th
en
wh
en
the s
ign
al
to n
ois
e r
ati
o o
f th
e r
ece
ived
sig
nal
fall
s, a
poin
t is
reach
ed
wh
en
th
e s
yn
c p
uls
e
am
pli
tud
e b
eco
mes
insu
ffic
ien
t to
keep
th
e p
ictu
re l
ock
ed
even
th
ou
gh
th
e p
ictu
re v
olt
age i
s
stil
l of
ad
equ
ate
am
pli
tud
e t
o y
ield
an
acc
ep
table
pic
ture
. O
n t
he o
ther
han
d i
f sy
nc
pu
lse
heig
ht
is i
ncr
ea
sed
at
the e
xp
en
se o
f th
e p
ictu
re d
eta
il,
then
un
der
sim
ila
r co
nd
itio
ns
the
rast
er
rem
ain
s lo
cked
bu
t th
e p
ictu
re c
on
ten
t is
of
too l
ow
an
am
pli
tud
e t
o s
et
up
a w
ort
hw
hil
e
pic
ture
. A
rati
o o
f P
/S =
10/4
, or
there
abou
t, r
esu
lts
in a
sit
uati
on
su
ch t
hat
wh
en
th
e s
ign
al
to
nois
e r
ati
o r
each
es
a c
ert
ain
low
level,
th
e s
yn
c am
pli
tud
e b
eco
mes
insu
ffic
ien
t, i
.e.,
th
e s
yn
c
fail
s at
the s
am
e t
ime a
s th
e p
ictu
re c
ease
s to
be o
f en
tert
ain
men
t valu
e.
Th
is r
ep
rese
nts
th
e
most
eff
icie
nt
use
of
the t
ele
vis
ion
syst
em
.
R =<â@EGã@A?BCVäAåFU?BGCV
Th
e h
ori
zon
tal
bla
nk
ing p
eri
od
an
d s
yn
c p
uls
e d
eta
ils
are
ill
ust
rate
d i
n F
ig.
3.3
. T
he i
nte
rval
betw
een
hori
zon
tal
scan
nin
g l
ines
is i
nd
icate
d b
y H
. A
s exp
lain
ed
earl
ier,
ou
t of
a t
ota
l li
ne
æ çè éêëççìí îïðñ òóñïôïõïöó÷ïðïï øùúûüýþÿ�� ï� �é� í ç�� çëè� �ì îê�è ��èæ çè éêëç ç�� ìî�� êì � ì� ç�� ìî � éêëç æ çè éêëç �� êì � ì�çìí îèè� �é�� êì � ì� ��� îç�ðñ î
m
�� ëè �éç � ì� �é�êè� �ì�óñ î
m
� �é�î�ìë ��� îç�ô òö î
m � êë ��éë �ó ò÷ î
m
� é�ìè ��éë �ð òó î
m�� ëè �éç � �õô î
m
� é�ìè ��éë�� êì çí�
� êë ��éë�� êì çí� �� ëè �éçî�êëç �ì è çéêîè çéùú û ü� ü�Ý �� Þ�ú ��5 � ��5 ��ú� ��������5 �� ��ú Þ���5 ��� ��ú ��� ���
�5 �ú � 2��������� ������ ü
��
�����������������������������
peri
od
of
64 µ
s, t
he l
ine b
lan
kin
g p
eri
od
is
12 µ
s. D
uri
ng t
his
in
terv
al
a l
ine s
yn
chro
niz
ing
pu
lse i
s in
sert
ed
. T
he p
uls
es
corr
esp
on
din
g t
o t
he d
iffe
ren
tia
ted
lea
din
g e
dges
of
the s
yn
c
pu
lses
are
act
uall
y u
sed
to s
yn
chro
niz
e t
he h
ori
zon
tal
scan
nin
g o
scil
lato
r. T
his
is
the r
easo
n
wh
y i
n F
ig.
3.3
an
d o
ther
figu
res
to f
oll
ow
, all
tim
e i
nte
rvals
are
sh
ow
n b
etw
een
syn
c p
uls
e
lead
ing e
dges.
Th
e l
ine b
lan
kin
g p
eri
od
is
div
ided
in
to t
hre
e s
ect
ion
s. T
hese
are
th
e ‘fr
on
t p
orc
h’, t
he
‘lin
e s
yn
c’ p
uls
e a
nd
th
e ‘back
porc
h’. T
he t
ime i
nte
rvals
all
ow
ed
to e
ach
part
are
su
mm
ari
zed
belo
w a
nd
th
eir
loca
tion
an
d e
ffect
on
th
e r
ast
er
is i
llu
stra
ted
in
Fig
. 3.3
.
Deta
ils o
f H
oriz
on
tal
Sca
nn
ing
Per
iod
Tim
e (µ
s)
Tota
l li
ne (
H)
64
Horz
bla
nk
ing
12 ±
.3
Horz
syn
c p
uls
e4.7
± 0
.2
Fro
nt
porc
h1.5
± .
3
Back
porc
h5.8
± .
3
Vis
ible
lin
e t
ime
52
Fro
nt
porc
h.
Th
is i
s a b
rief
cush
ion
ing p
eri
od
of
1.5
µs
inse
rted
betw
een
th
e e
nd
of
the
pic
ture
deta
il f
or
that
lin
e a
nd
th
e l
ead
ing e
dge o
f th
e l
ine s
yn
c p
uls
e. T
his
in
terv
al
all
ow
s th
e
rece
iver
vid
eo c
ircu
it t
o s
ett
le d
ow
n f
rom
wh
ate
ver
pic
ture
volt
age l
evel
exis
ts a
t th
e e
nd
of
the
pic
ture
lin
e t
o t
he b
lan
kin
g level befo
re t
he s
yn
c p
uls
e o
ccu
rs. T
hu
s sy
nc
circ
uit
s at
the r
ece
iver
are
iso
late
d f
rom
th
e i
nfl
uen
ce o
f en
d o
f th
e l
ine p
ictu
re d
eta
ils.
Th
e m
ost
str
ingen
t d
em
an
d i
s
mad
e o
n t
he v
ideo c
ircu
its
wh
en
peak
wh
ite d
eta
il o
ccu
rs a
t th
e e
nd
of
a l
ine.
Desp
ite t
he
exis
ten
ce o
f th
e f
ron
t p
orc
h w
hen
th
e l
ine e
nd
s in
an
extr
em
e w
hit
e d
eta
il,
an
d t
he s
ign
al
am
pli
tud
e t
ou
ches
alm
ost
zero
level,
th
e v
ideo v
olt
age l
evel
fail
s to
deca
y t
o t
he b
lan
kin
g l
evel
befo
re t
he l
ead
ing-e
dge o
f th
e l
ine s
yn
c p
uls
e o
ccu
rs. T
his
resu
lts
in l
ate
tri
ggeri
ng o
f th
e t
ime
base
cir
cuit
th
us
up
sett
ing t
he ‘
horz
’ li
ne s
yn
c ci
rcu
it.
As
a r
esu
lt t
he s
pot
(beam
) is
late
in
arr
ivin
g a
t th
e l
eft
of
the s
creen
an
d p
ictu
re i
nfo
rmati
on
on
th
e n
ext
lin
e i
s d
isp
lace
d t
o t
he
left
. T
his
eff
ect
is
kn
ow
n a
s ‘p
ull
ing-o
n-w
hit
es’
.
Lin
e sy
nc
pu
lse.
Aft
er
the f
ron
t p
roch
of
bla
nk
ing,
hori
zon
tal
retr
ace
is
pro
du
ced
wh
en
the s
yn
c p
uls
e s
tart
s. T
he f
lyback
is
defi
nit
ely
bla
nk
ed
ou
t beca
use
th
e s
yn
c le
vel
is b
lack
er
than
bla
ck. L
ine s
yn
c p
uls
es
are
sep
ara
ted
at
the r
ece
iver
an
d u
tili
zed
to k
eep
th
e r
ece
iver
lin
e
tim
e b
ase
in
pre
cise
syn
chro
nis
m w
ith
th
e d
ista
nt
tran
smit
ter.
Th
e n
om
inal
tim
e d
ura
tion
for
the l
ine s
yn
c p
uls
es
is 4
.7 µ
s. D
uri
ng t
his
peri
od
th
e b
eam
on
th
e r
ast
er
alm
ost
com
ple
tes
its
back
str
ok
e (
retr
ace
) an
d a
rriv
es
at
the e
xtr
em
e l
eft
en
d o
f th
e r
ast
er.
Ba
ck p
orc
h.
Th
is p
eri
od
of
5.8
µs
at
the b
lan
kin
g l
evel
all
ow
s p
len
ty o
f ti
me f
or
lin
e
flyback
to b
e c
om
ple
ted
. It
als
o p
erm
its
tim
e f
or
the h
ori
zon
tal
tim
e-b
ase
cir
cuit
to r
evers
e
dir
ect
ion
of
curr
en
t fo
r th
e i
nit
iati
on
of
the s
can
nin
g o
f n
ext
lin
e.
Infa
ct,
the r
ela
tive t
imin
gs
are
so s
et
that
small
bla
ck b
ars
(se
e F
ig.
3.3
) are
form
ed
at
both
th
e e
nd
s of
the r
ast
er
in t
he
hori
zon
tal p
lan
e. T
hese
bla
nk
ed
bars
at
the s
ides
have n
o e
ffect
on
th
e p
ictu
re d
eta
ils
rep
rod
uce
d
du
rin
g t
he a
ctiv
e l
ine p
eri
od
.
���:������������Y���
�;
Th
e b
ack
porc
h* a
lso p
rovid
es
the n
ece
ssa
ry a
mp
litu
de e
qu
al
to t
he b
lan
kin
g l
evel
(refe
ren
ce l
evel)
an
d e
na
ble
s to
pre
serv
e t
he d
c co
nte
nt
of
the p
ictu
re i
nfo
rma
tion
at
the
tran
smit
ter.
At
the r
ece
iver
this
level
wh
ich
is
ind
ep
en
den
t of
the p
ictu
re d
eta
ils
is u
tili
zed
in
the A
GC
(a
uto
ma
tic
ga
in c
on
trol)
cir
cuit
s to
develo
p t
rue A
GC
volt
age p
rop
ort
ion
al
to t
he
sign
al
stre
ngth
pic
ked
up
at
the a
nte
nn
a.
R =RTUE?GåBCVäAåFU?BGCV
Th
e v
ert
ical
syn
c p
uls
e t
rain
ad
ded
aft
er
each
fie
ld i
s so
mew
hat
com
ple
x i
n n
atu
re. T
he r
easo
n
for
this
ste
ms
from
th
e f
act
th
at
it h
as
to m
eet
severa
l exact
ing r
equ
irem
en
ts.
Th
ere
fore
, in
ord
er
to f
ull
y a
pp
reci
ate
th
e v
ari
ou
s co
nst
itu
en
ts o
f th
e p
uls
e t
rain
, th
e v
ert
ical
syn
c d
eta
ils
are
exp
lore
d s
tep
by s
tep
wh
ile e
xp
lain
ing t
he n
eed
for
its
vari
ou
s co
mp
on
en
ts.
Th
e b
asi
c vert
ical
syn
c ad
ded
at
the e
nd
of
both
even
ad
d o
dd
fie
lds
is s
how
n i
n F
ig. 3.4
.
Its
wid
th h
as
to b
e k
ep
t m
uch
la
rger
tha
n t
he h
ori
zon
tal
syn
c p
uls
e,
in o
rder
to d
eri
ve a
suit
able
fie
ld s
yn
c p
uls
e a
t th
e r
ece
iver
to t
rigger
the f
ield
sw
eep
osc
illa
tor.
Th
e s
tan
dard
s sp
eci
fy t
hat
the v
ert
ical sy
nc
peri
od
sh
ou
ld b
e 2
.5 t
o 3
tim
es
the h
ori
zon
tal
lin
e p
eri
od
. If
th
e w
idth
is
less
th
an
th
is, it
beco
mes
dif
ficu
lt t
o d
isti
ngu
ish
betw
een
hori
zon
tal
an
d v
ert
ical
pu
lses
at
the r
ece
iver. ��� ���� ���� �� !"#$ %� %� &' $ #() *+,� -�( .$/$0$1
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colo
ur
TV
tra
nsm
issi
on
a s
hort
sa
mp
le (
8 t
o 1
0 c
ycl
es)
of
the c
olo
ur
sub
carr
ier
osc
illa
tor
ou
tpu
t is
sen
t to
th
e r
ece
iver
for
pro
per
dete
ctio
n o
f co
lou
r si
gn
al
sid
eb
an
ds.
Th
is i
s k
now
n a
s co
lou
r
bu
rst
an
d i
s lo
cate
d a
t th
e b
ack
porc
h o
f th
e h
ori
zon
tal
bla
nk
ing p
ed
est
al.
�Ó
�����������������������������
If t
he w
idth
is
gre
ate
r th
an
th
is,
the t
ran
smit
ter
mu
st o
pera
te a
t p
eak
pow
er
for
an
un
nece
ssari
ly l
on
g i
nte
rval
of
tim
e.
In t
he 6
25 l
ine s
yst
em
2.5
lin
e p
eri
od
(2.5
× 6
4 =
160 µ
s)
has
been
all
ott
ed
for
the v
ert
ical
syn
c p
uls
es.
Th
us
a v
ert
ical
syn
c p
uls
e c
om
men
ces
at
the e
nd
of
1st
half
of
313th
lin
e (
en
d o
f fi
rst
field
) an
d t
erm
inate
s at
the e
nd
fo 3
15th
lin
e.
Sim
ilarl
y
aft
er
an
exact
in
terv
al
of
20 m
s (o
ne f
ield
peri
od
) th
e n
ext
syn
c p
uls
e o
ccu
pie
s li
ne n
um
bers
—
1st
, 2n
d a
nd
1st
half
of
thir
d,
just
aft
er
the s
eco
nd
fie
ld i
s over.
Note
th
at
the b
egin
nin
g o
f
these
pu
lses
has
been
ali
gn
ed
in
th
e f
igu
re t
o s
ign
ify t
hat
these
mu
st o
ccu
r aft
er
the e
nd
of
vert
ical
stro
ke o
f th
e b
eam
in
each
fie
ld,
i.e.
, aft
er
each
1/5
0th
of
a s
eco
nd
. T
his
ali
gn
men
t of
vert
ical
syn
c p
uls
es,
on
e a
t th
e e
nd
of
a h
alf
-lin
e p
eri
od
an
d t
he o
ther
aft
er
a f
ull
lin
e p
eri
od
(see F
ig.
3.4
), r
esu
lts
in a
rela
tive m
isali
gn
men
t of
the h
ori
zon
tal
syn
c p
uls
es
an
d t
hey d
o n
ot
ap
pear
on
e a
bove t
he o
ther
bu
t occ
ur
at
half
-lin
e in
terv
als
wit
h r
esp
ect
to e
ach
oth
er.
How
ever,
a d
eta
iled
exam
inati
on
of
the p
uls
e t
rain
s in
th
e t
wo f
ield
s w
ou
ld s
how
th
at
hori
zon
tal
syn
c
pu
lses
con
tin
ue t
o o
ccu
r exact
ly a
t 64 µ
s in
terv
als
(exce
pt
du
rin
g t
he v
ert
ical sy
nc
pu
lse p
eri
od
s)
thro
ugh
ou
t th
e s
can
nin
g p
eri
od
fro
m f
ram
e t
o f
ram
e a
nd
th
e a
pp
are
nt
shif
t of
32 µ
s is
on
ly d
ue
to t
he a
lign
men
t of
vert
ical
syn
c in
stan
ces
in t
he f
igu
re.
As
alr
ead
y m
en
tion
ed
th
e h
ori
zon
tal
syn
c in
form
ati
on
is
extr
act
ed
fro
m t
he s
yn
c p
uls
e
train
by d
iffe
ren
tiati
on
, i.
e., by p
ass
ing t
he p
uls
e t
rain
th
rou
gh
a h
igh
-pass
fil
ter.
In
deed
pu
lses
corr
esp
on
din
g t
o t
he d
iffe
ren
tiate
d l
ead
ing e
dges
of
syn
c p
uls
es
are
use
d t
o s
yn
chro
nis
e t
he
hori
zon
tal
scan
nin
g o
scil
lato
r. T
he p
roce
ss o
f d
eri
vin
g t
hese
pu
lses
is i
llu
stra
ted
in
Fig
. 3.5
.
Fu
rth
erm
ore
, re
ceiv
ers
oft
en
use
mon
ost
able
mu
ltiv
ibra
tors
to g
en
era
te h
ori
zon
tal
scan
, an
d
so a
pu
lse is
requ
ired
to in
itia
te e
ach
an
d e
very
cycl
e o
f th
e h
ori
zon
tal osc
illa
tor
in t
he r
ece
iver.
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Th
is b
rin
gs
ou
t th
e fir
st a
nd
most
obvio
us
short
com
ing o
f th
e w
avefo
rms
show
n in
Fig
.3.4
.
Th
e h
ori
zon
tal
syn
c p
uls
es
are
avail
able
both
du
rin
g t
he a
ctiv
e a
nd
bla
nk
ed
lin
e p
eri
od
s bu
t
there
are
no s
yn
c p
uls
es
(lead
ing e
dges)
avail
able
du
rin
g t
he 2
.5 lin
e v
ert
ical sy
nc
peri
od
. T
hu
s
the h
ori
zon
tal sw
eep
osc
illa
tor
that
op
era
tes
at
15625 H
z, w
ou
ld t
en
d t
o s
tep
ou
t of sy
nch
ron
ism
du
rin
g e
ach
vert
ical
syn
c p
eri
od
. T
he s
itu
ati
on
aft
er
an
od
d f
ield
is
even
wors
e.
As
show
n i
n
Fig
. 3
.4,
the v
ert
ica
l b
lan
kin
g p
eri
od
at
the e
nd
of
an
od
d f
ield
begin
s m
idw
ay t
hro
ugh
a
hori
zon
tal
lin
e.
Con
sequ
en
tly,
look
ing f
urt
her
alo
ng t
his
wavefo
rm,
we s
ee t
hat
the l
ead
ing
ed
ge o
f th
e v
ert
ical
syn
c p
uls
e c
om
es
at
the w
ron
g t
ime t
o p
rovid
e s
yn
chro
niz
ati
on
for
the
hori
zon
tal
osc
illa
tor.
Th
ere
fore
, it
beco
mes
nece
ssary
to c
ut
slots
in
th
e v
ert
ical
syn
c p
uls
e a
t
half
-lin
e-i
nte
rvals
to p
rovid
e h
ori
zon
tal
syn
c p
uls
es
at
the c
orr
ect
in
stan
ces
both
aft
er
even
an
d o
dd
fie
lds.
Th
e t
ech
niq
ue i
s to
tak
e t
he v
ideo s
ign
al
am
pli
tud
e b
ack
to t
he b
lan
kin
g l
evel
���:������������Y���
�
4.7
µs
befo
re t
he l
ine p
uls
es
are
need
ed
. T
he w
avefo
rm i
s th
en
retu
rned
back
to t
he m
axim
um
level
at
the m
om
en
t th
e l
ine s
weep
ci
rcu
it n
eed
s sy
nch
ron
izati
on
. T
hu
s fi
ve n
arr
ow
slo
ts o
f
4.7µ
s w
idth
get
form
ed
in
each
vert
ical
syn
c p
uls
e a
t in
terv
als
of
32 µ
s. T
he t
rail
ing b
ut
risi
ng
ed
ges
of
these
pu
lses
are
act
ua
lly u
sed
to t
rigger
the h
ori
zon
tal
osc
illa
tor.
Th
e r
esu
ltin
g
wavefo
rms
togeth
er
wit
h l
ine n
um
bers
an
d t
he d
iffe
ren
tiate
d o
utp
ut
of
both
th
e f
ield
tra
ins
is
illu
stra
ted
in
Fig
. 3.6
. T
his
in
sert
ion
of
short
pu
lses
is k
now
n a
s n
otc
hin
g o
r se
rrati
on
of
the
bro
ad
fie
ld p
uls
es.
Note
th
at
thou
gh
th
e v
ert
ical
pu
lse h
as
been
bro
ken
to y
ield
hori
zon
tal
syn
c p
uls
es,
th
e
eff
ect
on
th
e v
ert
ical
pu
lse i
s su
bst
an
tiall
y u
nch
an
ged
. It
sti
ll r
em
ain
s above t
he b
lan
kin
g
volt
age l
evel
all
of
the t
ime i
t is
act
ing. T
he p
uls
e w
idth
is
stil
l m
uch
wid
er
than
th
e h
ori
zon
tal
pu
lse w
idth
an
d t
hu
s ca
n b
e e
asi
ly s
ep
ara
ted
at
the r
ece
iver.
Retu
rnin
g t
o F
ig.
3.6
it
is s
een
that
each
hori
zon
tal
syn
c p
uls
e y
ield
s a p
osi
tive s
pik
ed
ou
tpu
t fr
om
its
lead
ing e
dge a
nd
a
negati
ve s
pik
ed
pu
lse f
rom
its
tra
ilin
g e
dge.
Tim
e-c
on
stan
t of
the d
iffe
ren
tiati
ng c
ircu
it i
s so
chose
n,
that
by t
he t
ime a
tra
ilin
g e
dge a
rriv
es,
th
e p
uls
e d
ue t
o t
he l
ead
ing e
dge h
as
just
abou
t d
eca
yed
. T
he n
egati
ve-g
oin
g t
riggeri
ng p
uls
es
may b
e r
em
oved
wit
h a
dio
de s
ince
on
ly
the p
osi
tive g
oin
g p
uls
es
are
eff
ect
ive i
n l
ock
ing t
he h
ori
zon
tal
osc
illa
tor.
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How
ever,
th
e p
uls
es
act
ua
lly u
tili
zed
are
th
e o
nes
tha
t occ
ur
seq
uen
tia
lly a
t 6
4 µ
s
inte
rvals
. S
uch
pu
lses
are
mark
ed
wit
h l
ine n
um
bers
for
both
th
e f
ield
s. N
ote
th
at
du
rin
g t
he
inte
rvals
of
serr
ate
d v
ert
ical
pu
lse t
rain
s, a
ltern
ate
vert
ical
spik
es
are
uti
lized
. T
he p
uls
es
not
use
d i
n o
ne f
ield
are
th
e o
nes
uti
lized
du
rin
g t
he s
eco
nd
fie
ld.
Th
is h
ap
pen
s beca
use
of
the
half
-lin
e d
iffe
ren
ce a
t th
e c
om
men
cem
en
t of
each
fie
ld a
nd
th
e f
act
th
at
notc
hed
vert
ical
syn
c
pu
lses
occ
ur
at
inte
rvals
of
32 µ
s an
d n
ot
64 µ
s as
requ
ired
by t
he h
ori
zon
tal
sweep
osc
illa
tor.
Th
e p
uls
es
that
com
e a
t a t
ime w
hen
th
ey c
an
not
trig
ger
the o
scil
lato
r are
ign
ore
d.
Th
us
the
requ
irem
en
t of
keep
ing t
he h
ori
zon
tal
sweep
cir
cuit
lock
ed
desp
ite i
nse
rtio
n o
f vert
ical
syn
c
pu
lses
is r
eali
zed
.
Now
we t
urn
to t
he s
eco
nd
sh
ort
com
ing o
f th
e w
avefo
rm o
f F
ig.
3.4
. F
irst
it
mu
st b
e
men
tion
ed
th
at
syn
chro
niz
ati
on
of
the v
ert
ica
l sw
eep
osc
illa
tor
in t
he r
ece
iver
is o
bta
ined
from
vert
ical
syn
c p
uls
es
by i
nte
gra
tion
. T
his
is
illu
stra
ted
in
Fig
. 3.5
wh
ere
th
e t
ime-c
on
stan
t
R2C
2 i
s ch
ose
n t
o b
e l
arg
e c
om
pare
d t
o t
he d
ura
tion
of
hori
zon
tal
pu
lses
bu
t n
ot
wit
h r
esp
ect
to
wid
th o
f th
e v
ert
ical
syn
c p
uls
es.
Th
e i
nte
gra
tin
g c
ircu
it m
ay e
qu
all
y b
e l
ook
ed
up
on
as
a l
ow
-
pass
fil
ter,
wit
h a
cu
it-o
ff f
requ
en
cy s
uch
th
at
the h
ori
zon
tal
syn
c p
uls
es
pro
du
ce v
ery
lit
tle
ou
tpu
t, w
hil
e t
he v
ert
ical
pu
lses
have a
fre
qu
en
cy t
hat
fall
s in
th
e p
ass
-ban
d o
f th
e f
ilte
r. T
he
volt
age b
uil
t acr
oss
th
e c
ap
aci
tor
of
the l
ow
-pass
fil
ter
(in
tegra
tin
g c
ircu
it)
corr
esp
on
din
g t
o
the s
yn
c p
uls
e t
rain
s of
both
th
e f
ield
s is
sh
ow
n i
n F
ig.
3.7
. N
ote
th
at
each
hori
zon
tal
pu
lse
cau
ses
a s
ligh
t ri
se i
n v
olt
age a
cross
th
e c
ap
aci
tor
bu
t th
is i
s re
du
ced
to z
ero
by t
he t
ime t
he
next
pu
lse a
rriv
es.
Th
is i
s so
, beca
use
th
e c
harg
ing p
eri
od
for
the c
ap
aci
tor
is o
nly
4.7
µs
an
d
the v
olt
age a
t th
e i
np
ut
to t
he i
nte
gra
tor
rem
ain
s at
zero
for
the r
est
of
the p
eri
od
of
59.3
µs.
Hen
ce t
here
is
no r
esi
du
al
volt
age a
cross
th
e v
ert
ical
filt
er
(L.P
. fi
lter)
du
e t
o h
ori
zon
tal
syn
c-
pu
lses.
On
ce t
he b
road
serr
ate
d v
ert
ical
pu
lse a
rriv
es
the v
olt
age a
cross
th
e o
utp
ut
of
the f
ilte
r
start
s in
creasi
ng. H
ow
ever,
th
e b
uil
t u
p v
olt
age d
iffe
rs f
or
each
fie
ld. T
he r
easo
n is
not
dif
ficu
lt
to f
ind
. A
t th
e b
egin
nin
g o
f th
e f
irst
fie
ld (
od
d f
ield
) th
e l
ast
horz
syn
c p
uls
e c
orr
esp
on
din
g t
o
the b
egin
nin
g o
f 625th
lin
e i
s se
para
ted
fro
m t
he 1
st v
ert
ical
pu
lse b
y f
ull
on
e l
ine a
nd
an
y
volt
age d
evelo
ped
acr
oss
th
e f
ilte
r w
ill
have e
nou
gh
tim
e t
o r
etu
rn t
o z
ero
befo
re t
he a
rriv
al
of
the f
irst
vert
ical
pu
lse, an
d t
hu
s th
e f
ilte
r ou
tpu
t volt
age b
uil
ds
up
fro
m z
ero
in
resp
on
se t
o t
he
five s
ucc
ess
ive
bro
ad
vert
ical
syn
c p
uls
es.
Th
e v
olt
age b
uil
ds
up
beca
use
th
e c
ap
aci
tor
has
more
tim
e t
o c
harg
e a
nd
on
ly 4
.7 µ
s to
dis
charg
e.
Th
e s
itu
ati
on
, h
ow
ever,
is
not
the s
am
e f
or
the b
egin
nin
g o
f th
e 2
nd
(even
) fi
eld
. H
ere
th
e l
ast
hori
zon
tal
pu
lse c
orr
esp
on
din
g t
o t
he
begin
nin
g o
f 313th
lin
e is
sep
ara
ted
fro
m t
he fir
st v
ert
ical p
uls
e b
y o
nly
half
-a-l
ine. T
he v
olt
age
develo
ped
acr
oss
th
e v
ert
ical
filt
er
wil
l th
us
not
have e
nou
gh
tim
e t
o r
each
zero
befo
re t
he
arr
ival
of
the f
irst
vert
ical
pu
lse,
wh
ich
mean
s th
at
the v
olt
age b
uil
d-u
p d
oes
not
start
fro
m
zero
, as
in t
he c
ase
of
the 1
st f
ield
. T
he r
esi
du
al
volt
age o
n a
ccou
nt
of
the h
alf
lin
e d
iscr
ep
an
cy
gets
ad
ded
to t
he v
olt
age d
evelo
ped
on
acc
ou
nt
of
the b
road
vert
ical
pu
lses
an
d t
hu
s th
e
volt
age d
evelo
ped
acr
oss
th
e o
utp
ut
filt
er
is s
om
e w
hat
hig
her
at
each
in
stan
t as
com
pare
d t
o
the v
olt
age d
evelo
ped
at
the b
egin
nin
g o
f th
e f
irst
-fie
ld.
Th
is i
s sh
ow
n i
n d
ott
ed
ch
ain
lin
e i
n
Fig
.3
.7. Th
e v
ert
ica
l osc
illa
tor
trig
ger
pote
nti
al
level
ma
rked
as
trig
ger
level
in t
he d
iagra
m
(Fig
.3.7
) in
ters
ect
s th
e t
wo f
ilte
r ou
tpu
t p
rofi
les
at
dif
fere
nt
poin
ts w
hic
h i
nd
icate
s th
at
in t
he
case
of
seco
nd
fie
ld t
he o
scil
lato
r w
ill
get
trig
gere
d a
fra
ctio
n o
f a s
eco
nd
too s
oon
as
com
pare
d
���:������������Y���
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to t
he f
irst
fie
ld. N
ote
th
at
this
in
equ
lity
in
pote
nti
al
levels
for
the t
wo f
ield
s co
nti
nu
es
du
rin
g
the p
eri
od
of
dis
charg
e o
f th
e c
ap
aci
tor
on
ce t
he v
ert
ical sy
nc
pu
lses
are
over
an
d t
he h
ori
zon
tal
syn
c p
uls
es
tak
e-o
ver.
Th
ou
gh
th
e a
ctu
al
tim
e d
iffe
ren
ce i
s qu
ite s
hort
it
does
pro
ve s
uff
icie
nt
to u
pse
t th
e d
esi
red
in
terl
aci
ng s
equ
en
ce. } ~� ��� ~��� ���� ���� ��� ���� } ~� ��� ���� ���� ~��� ��� ������
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Equ
ali
zin
g p
uls
es.
To t
ak
e c
are
of
this
dra
wback
wh
ich
occ
urs
on
acc
ou
nt
of
the h
alf
-
lin
e d
iscr
ep
an
cy f
ive n
arr
ow
pu
lses
are
ad
ded
on
eit
her
sid
e o
f th
e v
ert
ical
syn
c p
uls
es.
Th
ese
are
kn
ow
n a
s p
re-e
qu
ali
zin
g a
nd
post
-equ
ali
zin
g p
uls
es.
Each
set
con
sist
s of
five n
arr
ow
pu
lses
occ
up
yin
g 2
.5 l
ines
peri
od
on
eit
her
sid
e o
f th
e v
ert
ical
syn
c p
uls
es.
Pre
-equ
ali
zin
g a
nd
post
-
equ
ali
zin
g p
uls
e d
eta
ils
wit
h l
ine n
um
bers
occ
up
ied
by t
hem
in
each
fie
ld a
re g
iven
in
Fig
. 3.8
.
Th
e e
ffect
of
these
pu
lses
is t
o s
hif
t th
e h
alf
-lin
e d
iscr
ep
an
cy a
way b
oth
fro
m t
he b
egin
nin
g
an
d e
nd
of
vert
ical
syn
c p
uls
es.
Pre
-equ
ali
zin
g p
uls
es
bein
g o
f 2.3
µs
du
rati
on
resu
lt i
n t
he
dis
charg
e o
f th
e c
ap
aci
tor
to e
ssen
tiall
y z
ero
volt
age i
n b
oth
th
e f
ield
s, d
esp
ite t
he h
alf
-lin
e
dis
crep
an
cy b
efo
re t
he v
olt
age b
uil
d-u
p s
tart
s w
ith
th
e a
rriv
al
of
vert
ical
syn
c p
uls
es.
Th
is i
s
illu
stra
ted
in
Fig
. 3.9
. P
ost
-equ
ali
zin
g p
uls
es
are
nece
ssary
for
a f
ast
dis
charg
e o
f th
e c
ap
aci
tor
to e
nsu
re t
riggeri
ng o
f th
e v
ert
ical
osc
illa
tor
at
pro
per
tim
e.
If t
he d
eca
y o
f volt
age a
cross
th
e
cap
aci
tor
is s
low
as
wou
ld h
ap
pen
in
th
e a
bse
nce
of
post
-equ
ali
zin
g p
uls
es,
th
e o
scil
lato
r m
ay
trig
ger
at
the t
rail
ing e
dge w
hic
h m
ay b
e f
ar-
aw
ay f
rom
th
e l
ead
ing e
dge a
nd
th
is c
ou
ld l
ead
to
an
err
or
in t
riggeri
ng.
Th
us
wit
h t
he i
nse
rtio
n o
f n
arr
ow
pre
an
d p
ost
equ
ali
zin
g p
uls
es,
th
e v
olt
age r
ise a
nd
fall
pro
file
is
ess
en
tiall
y t
he s
am
e f
or
both
th
e f
ield
sequ
en
ces
(see F
ig.
3.9
) an
d t
he v
ert
ical
osc
illa
tor
is t
riggere
d a
t th
e p
rop
er
inst
an
ts,
i.e.
, exact
ly a
t an
in
terv
al
of
1/5
0th
of
a s
eco
nd
.
�X
�����������������������������
Th
is p
roble
m c
ou
ld p
oss
ibly
als
o b
e s
olv
ed
by u
sin
g a
n i
nte
gra
tin
g c
ircu
it w
ith
a m
uch
larg
er
tim
e c
on
sta
nt,
to e
nsu
re t
ha
t th
e c
ap
aci
tor
rem
ain
s vir
tua
lly u
nch
arg
ed
by t
he h
ori
zon
tal
pu
lses.
How
ever,
th
is w
ou
ld h
ave t
he e
ffect
of
sign
ific
an
tly r
ed
uci
ng t
he i
nte
gra
tor
ou
tpu
t fo
r
vert
ica
l p
uls
es
so t
ha
t a
vert
ica
l sy
nc
am
pli
fier
wou
ld h
ave t
o b
e u
sed
. In
a b
roa
dca
stin
g
situ
ati
on
, th
ere
are
th
ou
san
ds
of
rece
ivers
for
every
tra
nsm
itte
r. C
on
seq
uen
tly i
t is
mu
ch
more
eff
icie
nt
an
d e
con
om
ical
to c
ure
th
is p
roble
m i
n o
ne t
ran
smit
ter
than
in
th
ou
san
ds
of
rece
ivers
. T
his
, as
exp
lain
ed
above,
is a
chie
ved
by t
he u
se o
f p
re a
nd
post
equ
ali
zin
g p
uls
es.
Th
e c
om
ple
te p
uls
e t
rain
s fo
r both
th
e f
ield
s i
nco
rpora
tin
g e
qu
ali
zin
g p
uls
es
are
sh
ow
n i
n
Fig
.3
.10
.
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Fro
m t
he c
om
pari
son
of th
e h
ori
zon
tal an
d v
ert
ical ou
tpu
t p
uls
e form
s sh
ow
n in
Fig
s.3.7
an
d 3
.9 i
t ap
pears
th
at
the v
ert
ical
trig
ger
pu
lse (
ou
tpu
t of
the l
ow
-pass
fil
ter)
is
not
very
sharp
bu
t act
uall
y i
t is
not
so.
Th
e s
cale
ch
ose
n e
xaggera
tes
the e
xte
nt
of
the v
ert
ical
pu
lses.
Th
e v
olt
age b
uil
d-u
p p
eri
od
is
on
ly 1
60 µ
s an
d s
o f
ar
as
the v
ert
ical
syn
chro
niz
ing o
scil
lato
r is
con
cern
ed
th
is p
uls
e o
ccu
rs r
ap
idly
an
d r
ep
rese
nts
a s
ud
den
ch
an
ge i
n v
olt
age w
hic
h d
eca
ys
very
fast
.
Th
e p
ola
rity
of
the p
uls
es
as
obta
ined
at
the o
utp
uts
of
their
resp
ect
ive f
ield
s m
ay n
ot
be
suit
able
for
dir
ect
ap
pli
cati
on
in
th
e c
on
troll
ed
syn
chro
niz
ing o
scil
lato
r an
d m
igh
t n
eed
in
vers
ion
dep
en
din
g o
n t
he t
yp
e o
f osc
illa
tor
use
d.
Th
is a
spect
wil
l be f
ull
y d
evelo
ped
in
th
e c
hap
ter
devote
d t
o v
ert
ical
an
d h
ori
zon
tal
osc
illa
tors
.
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R =ËVåBAAGADVULÌUAåUFU?BGCV
A c
om
ple
te c
hart
giv
ing l
ine n
um
bers
an
d p
uls
e d
esi
gn
ati
on
s fo
r both
th
e f
ield
s (c
orr
esp
on
din
g
to F
ig.
3.1
0)
is g
iven
belo
w :
Fir
st
Fie
ld (
od
d f
ield
)
Lin
e n
um
ber
s :
on
e to
1st
-ha
lf o
f 31
3th
lin
e (3
12.5
lin
es)
1,
2 a
nd
3rd
1st
-ha
lf,
lin
es
2.5
lin
es—
Vert
ica
l sy
nc
pu
lses
3rd
2n
d-h
alf
, 4
, a
nd
52
.5 l
ines—
Post
-vert
ica
l sy
nc
eq
ua
lizin
g p
uls
es.
6 t
o 1
7,
an
d 1
8th
1st
-half
12.5
lin
es—
Bla
nk
ing r
etr
ace
pu
lses
18th
2n
d-h
alf
to 3
10
292.5
lin
es—
Pic
ture
deta
ils
311,
312,
an
d 3
13th
1st
-half
2.5
lin
es—
Pre
-vert
ical
syn
c equ
ali
zin
g p
uls
es
for
the 2
nd
fie
ld.
Tota
l n
um
ber
of
lin
es =
312.5
Seco
nd
fie
ld (
ev
en
fie
ld)
Lin
e n
um
ber
s :
313th
2n
d-h
alf
to 6
25 (
312.5
lin
es)
313th
2n
d-h
alf
, 314,
315
2.5
lin
es—
Vert
ical
syn
c p
uls
es
316,
317,
318th
1st
-half
2.5
lin
es—
Post
-vert
ical
syn
c equ
ali
zin
g p
uls
es
318th
2n
d-h
alf
-to 3
30
12.5
lin
es—
Bla
nk
ing r
etr
ace
pu
lses
33
1 t
o 1
st-h
alf
of
62
3rd
29
2.5
lin
e—
Pic
ture
deta
ils
623 2
nd
-half
, 624 a
nd
625
2.5
lin
es—
Pre
-vert
ical
syn
c equ
ali
zin
g p
uls
es
for
the 1
st f
ield
Tota
l n
um
ber
of
lin
es =
31
2.5
Tota
l N
um
ber
of
Lin
es p
er F
ram
e =
625
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���:������������Y���
�Ô
Ap
pro
xim
ate
loca
tion
of li
ne
nu
mber
s. T
he s
err
ate
d v
ert
ical sy
nc
pu
lse forc
es
the v
ert
ical
defl
ect
ion
cir
cuit
y t
o s
tart
th
e f
lyback
. H
ow
ever,
th
e f
lyback
gen
era
lly d
oes
not
begin
wit
h t
he
start
of
vert
ical
syn
c beca
use
th
e s
yn
c p
uls
e m
ust
bu
ild
up
a m
inim
um
volt
age a
cross
th
e
cap
aci
tor
to t
rigger
the s
can
nin
g o
scil
lato
r. I
f it
is
ass
um
ed
th
at
vert
ical
flyback
sta
rts
wit
h
the l
ead
ing e
dge o
f th
e f
ou
rth
serr
ati
on
, a t
ime o
f 1.5
lin
es
pass
es
du
rin
g v
ert
ical
syn
c befo
re
vert
ical
flyback
sta
rts.
Als
o f
ive e
qu
ali
zin
g p
uls
es
occ
ur
befo
re v
ert
ical
syn
c p
uls
e t
rain
sta
rts.
Th
en
fou
r li
nes
(2.5
+ 1
.5 =
4)
are
bla
nk
ed
at
the b
ott
om
of
the p
rict
ure
befo
re v
ert
ical
retr
ace
begin
s. A
typ
ical
vert
ical
retr
ace
tim
e i
s fi
ve l
ines.
Th
us
the r
em
ain
ing e
leven
(20 –
(4
+ 5
) =
11)
lin
es
are
bla
nk
ed
at
the t
op
of
the r
ast
er.
Th
ese
lin
es
pro
vid
e t
he s
weep
osc
illa
tor
en
ou
gh
tim
e t
o a
dju
st t
o a
lin
ear
rise
for
un
iform
pic
k-u
p a
nd
rep
rod
uct
ion
of
the p
ictu
re.
R =%&ÌAå?G@AV@&TUE?GåBC'ÌCVU?EBGA
By s
err
ati
ng t
he v
ert
ical
syn
c p
uls
es
an
d t
he p
rovid
ing p
re-
an
d p
ost
-equ
ali
zin
g p
uls
es
the
foll
ow
ing b
asi
c re
qu
irem
en
ts n
ece
ssary
for
succ
ess
ful
inte
rlace
d s
can
nin
g a
re e
nsu
red
.
(a)
A s
uit
able
fie
ld s
yn
c p
uls
e i
s d
eri
ved
for
trig
geri
ng t
he f
ield
osc
illa
tor.
(b)
Th
e l
ine o
scil
lato
r co
nti
nu
es
to r
ece
ive t
riggeri
ng p
uls
es
at
corr
ect
in
terv
als
wh
ile t
he
pro
cess
of
init
iati
on
an
d c
om
ple
tion
of
the f
ield
tim
e-b
ase
str
ok
e i
s goin
g o
n.
(c)
It b
eco
mes
poss
ible
to i
nse
rt v
ert
ical
syn
c p
uls
es
at
the e
nd
of
a l
ine a
fter
the 2
nd
field
an
d a
t th
e m
idd
le o
f a lin
e a
t th
e e
nd
of th
e 1
st fie
ld w
ith
ou
t ca
usi
ng a
ny in
terl
ace
err
or.
(d)
Th
e v
ert
ical
syn
c bu
ild
up
at
the r
ece
iver
has
pre
cise
ly t
he s
am
e s
hap
e a
nd
tim
ing o
n
od
d a
nd
even
fie
lds.
R =>VäAåFU?BGCV@&?âU%<%CGAUVäV?UW
In t
he 5
25 l
ine A
meri
can
TV
syst
em
wh
ere
th
e t
ota
l n
um
ber
of
lin
es
scan
ned
per
seco
nd
is
15750,
the s
yn
c p
uls
e d
eta
ils
are
as
un
der
:
Deta
ils o
f H
orz B
lan
kin
g
Per
iod
Tim
e ( µ
s)
Fie
ld l
ine (
H)
63
.5
Horz
bla
nk
ing
9.5
to 1
1.5
Horz
syn
c p
uls
e4.7
5 ±
0.5
Fro
nt
porc
h1
.26
(m
inim
um
)
Ba
ck p
orc
h3
.81
(m
inim
um
)
Vis
ible
lin
e5
2 t
o 5
4
Deta
ils o
f v
erti
ca
l B
lan
kin
g
Per
iod
Tim
e
Tota
l fi
eld
(V
) p
eri
od
= 1
/60
sec.
= 1
6.7
ms
Vis
ible
fie
ld t
ime
= 1
5 t
o 1
6 m
s
Vert
ica
l b
lan
kin
g=
0.8
to 1
.3 m
s
|�
�����������������������������
Tota
l d
ura
tion
of
six (
serr
ate
d)
vert
ica
l sy
nc
pu
lses
= 3
H =
190.5
µs
Each
serr
ate
d p
uls
e=
H/2
= 3
1.7
5 µ
s
Each
equ
ali
zin
g p
uls
e
(Six
pre
- a
nd
six
post
-eq
ua
ilzin
g p
uls
es
are
pro
vid
ed
at
H/2
in
terv
als
)=
0.0
4 H
= 2
.54 µ
s
E H IJ H KL MHNOJ PQN1
.S
ketc
h c
om
posi
te v
ideo s
ign
al
wa
vefo
rm f
or
at
lea
st t
hre
e t
hre
e s
ucc
ess
ive l
ines
an
d i
nd
ica
te :
(i)
extr
em
e w
hit
e l
evel,
(ii
) b
lan
kin
g l
evel,
(ii
) p
ed
est
al
heig
ht
an
d (
iv)
syn
c p
uls
e l
evel.
Ju
stif
y
the c
hoic
e o
f P
/S r
ati
o =
10
/4 i
n t
he c
om
posi
te s
ign
al.
Wh
y i
s th
e c
om
bin
ing o
f p
ictu
re s
ign
al
an
d
syn
c p
uls
es
call
ed
a v
olt
age d
ivis
ion
mu
ltip
lex ?
2.
Sk
etc
h c
om
posi
te v
ideo s
ign
al
wa
vefo
rms
for
the p
ictu
re i
nfo
rma
tion
sh
ow
n i
n F
ig.
P 3
.1.
( ) * +,*-,
./ +0 10 +21+34 504 6+7 10 +28 5133 ùú û ü£� ü/3
.S
how
pic
ture
in
form
ati
on
on
a r
ast
er
for
the v
ideo s
ign
als
dra
wn
in
Fig
. P
3.2
.
9:;< => =?=>@A B
@A B
C DECFE ùú û ü£� üý
4.
Sk
etc
h t
he d
eta
ils
of
hori
zon
tal
bla
nk
ing a
nd
syn
c p
uls
es.
La
bel
on
it
(i)
fron
t p
orc
h,
(ii)
hori
zon
-
tal
syn
c p
uls
e,
(iii
) back
porc
h a
nd
(iv
) a
ctiv
e l
ine p
eri
od
s. W
hy a
re t
he f
ron
t p
orc
h a
nd
ba
ck
porc
h i
nte
rva
ls p
rovid
ed
befo
re a
nd
aft
er
the h
ori
zon
tal
syn
c p
uls
e ?
Exp
lain
wh
y t
he b
lan
kin
g
pu
lses
are
not
use
d a
s sy
nc
pu
lses.
5.
En
um
era
te t
he b
asi
c re
qu
rim
en
ts t
ha
t m
ust
be s
ati
sfie
d b
y t
he p
uls
e t
rain
ad
ded
aft
er
ea
ch
field
. W
hy i
s it
nece
ssa
ry t
o s
err
ate
th
e b
roa
d v
ert
ica
l sy
nc
pu
lse ?
6.
Sk
etc
h t
he p
uls
e t
rain
s th
at
foll
ow
aft
er
the s
eco
nd
an
d f
irst
fie
ld o
f a
ctiv
e s
can
nin
g.
Wh
y a
re
the v
ert
ica
l sy
nc
pu
lses
notc
hed
at
32
µs
inte
rval
an
d n
ot
at
64 µ
s in
terv
al
to p
rovid
e h
ori
zon
tal
syn
c p
uls
es
?
���:������������Y���
GH
7.
Exp
lain
how
th
e h
ori
zon
tal
an
d v
ert
ica
l sy
nc
pu
lses
are
sep
ara
ted
an
d s
ha
ped
at
the r
ece
iver.
For
a t
ime c
on
sta
nt
of
5 µ
s fo
r th
e d
iffe
ren
tia
tin
g c
ircu
it,
an
d 1
00
µs
for
the i
nte
gra
tin
g c
ircu
it,
plo
t th
e o
utp
ut
wa
vefo
rms
from
both
th
e c
ircu
its
for
the e
nti
re v
ert
ica
l p
eri
od
. C
alc
ula
te t
he
err
or
in t
imin
g f
or
succ
ess
ive v
ert
ica
l fi
eld
s in
th
e a
bse
nce
of
eq
ua
lizin
g p
uls
es.
8.
Sk
etc
h t
he c
om
ple
te p
uls
e t
rain
s th
at
foll
ow
at
the e
nd
of
both
od
d a
nd
even
fie
lds.
Fu
lly l
ab
el
them
an
d e
xp
lain
how
th
e h
alf
lin
e d
iscr
ep
an
cy i
s re
moved
by i
nse
rtio
n o
f p
re-e
qu
ali
zin
g p
uls
es.
9.
Ju
stif
y t
he n
eed
for
pre
an
d p
ost
eq
ua
lizin
g p
uls
es.
Wh
y i
t is
nece
ssa
ry t
o k
eep
th
eir
du
rati
on
eq
ua
l to
th
e h
alf
-lin
e p
eri
od
?
10
.J
ust
ify t
he n
eed
for
a b
lan
kin
g p
eri
od
corr
esp
on
din
g t
o 2
0 c
om
ple
te l
ines
aft
er
ea
ch a
ctiv
e f
ield
of
sca
nn
ing.
Wh
y d
oes
the v
ert
ica
l re
tra
ce n
ot
begin
wit
h t
he i
nco
min
g o
f th
e f
irst
serr
ate
d
vert
ica
l sy
nc
pu
lse ?
11
.S
ketc
h t
he c
om
ple
te p
uls
e t
rain
s th
at
foll
ow
at
the e
nd
of
od
d a
nd
even
fie
lds
in t
he 5
25
lin
e
tele
vis
ion
syst
em
. J
ust
ify t
he n
eed
for
six i
nst
ea
d o
f fi
ve p
re a
nd
post
eq
ua
lizin
g p
uls
es.
12
.S
how
by a
ny s
uit
able
mean
s ap
pro
xim
ate
corr
esp
on
den
ce b
etw
een
lin
e n
um
bers
an
d t
he l
oca
tion
of
the e
lect
ron
bea
m o
n t
he s
creen
, b
oth
for
od
d a
nd
even
fie
lds.
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