View
5
Download
0
Category
Preview:
Citation preview
mikedzText Box2
mikedzText Boxr
mdzText Boxdoubled in height
mdzText Box^
mdzText Box^
Le+: " Ci: ,..._..._.. ..... ···.·.·· .. · ... · .. · .. · .. · ....... ·.·.·.·.·.· .. ......................................... ~e•\~Yfll~~~
;) = '){ (-l) + ~ ')C (~)-~l.. J~ ') ""'b?!!':. -- ---+"'--- . "-''4
",.{t):...L.... ,. -J Co~~ "l'r± ~- -= a-, ~ o . ._,_el, 'lll•.L
·························· .... · ... · .. ·.·.· ... ·.· .... ·.· .......... =.: ..... 'II ~?~ .... .
(~):
.,,. ••'VO·~·'"•" ("\.)COS(Wc y.-~
____ JY(w
-we
0
0
mdzText Boxamplitude doubled
sn,~~'""e: Fl .. $\,.-~u>I +~o trif. ;J.et-.tli-\es: ' - :)
cos' Ce): t.,.. i: co.s(z&) S\t\ (t.")::: ~ si"'& C'ose ("t_ ~_')('_(f;-) co.s (wr, t) - ~ (-f:) S '" (Wet)
')(..(t)~ "(-t.)•~
.;co"'"''. Jew- : /\(" ( t) ~---~~- ~cos.( Ulc t) ru-_(.:b) ~ ?C(i) 2 C'~~"' ~) _ _--~Ct) as,·~(t.br.t~cos.
: ')(-(~) (TI co s.(2.W~t"\ - ~ ('E)_S_\~l\(tu:i-·} ;: ')C (t) +-=-f '>C(t)cos(2wct) - ~ (-l) si~(zwr.~v-
s\"'i 1~~ to (t)·········~··" r•vi•'4l,1 par• &~l a\- +I\, ce. r-r er f~•'"."'1
~,,. L PF +• \'/(•)\ e)l t ....,~·
f6• "\pr Tval\ Sai~o """' P ... \r ___ _,,.j H""'
Ya(jw)
~ I -wa
Yb(jw)
(l I -wb
Y0 (jw)
~ I -we
W(jw)
I
~ -wa
(l -wb
w
w
/\ We W
Figure 8. 16 Spectra associated with the frequency-division multiplexing system of Figure 8.15.
X(jw)
A -wM WM
(a)
Y(jw)
A t 6 w sideband sideband (b) sideband sideband
Yu(jw)
~ it ~ -we We w
(c)
)j(joo)
it Figure 8.19 [
~ ~ sideband modulat modulating signal ter modulation wi·
-we We (J) rier; (c) spectrum sidebands; (d) sp
(d) lower sidebands.
mdzText Box-
mdzText Boxupper
-VV o Aft ev
>O Xp(t) H(Jw)- +j w t t) ..._...--ec-\Vl/\r'V\ sh:f~~~ 'tc- \ ~~ \?0 CL~. f't'\
Sec. 8.4 Single-Sideband Sinusoidal Amplitude Modulation 597
Frequency Propagation Channel range Designation Typical uses method features
30-300Hz ELF Macrowave, submarine com- Megametric waves Penetration of conducting (extremely munication . earth and seawater low frequency)
0.3-3 kHz VF Data terminals, telephony Copper wire (voice frequency)
3-30kHz VLF Navigation, telephone, tele- Surface ducting Low attenuation, little fading, (very low fre- graph, frequency and tirning (ground wave) extremely stable phase and quency) standards frequency, large antennas
30-300kHz LF Industrial (power line) com- Mostly surface ducting Slight fading, high atrno-(low frequency) munication, aeronautical
and maritime long-range spheric pulse
navigation, radio beacons 0.3-3MHz MF Mobile, AM broadcasting, Ducting and ionospheric Increased fading, but reliable
(medium frequency) amateur, public safety reflection (sky wave) 3-30MHz HF Military communication, aero- Ionospheric reflecting sky Intermittent and frequency-
(high frequency) nautical mobile, intema- wave, 50-400 km layer selective fading, multipath tional fixed, amateur and altitudes citizen's band, industrial
30-300MHz VHF FM and TV broadcast, land Sky wave (ionospheric and Fading, scattering, and multi-(very high transportation (taxis, buses, tropospheric scatter) path frequency) railroad)
0.3-3 GHz UHF UHF TY, space telemetry, Transhorizon tropospheric (ultra high radar, military scatter and line-of-sight frequency) relaying
3-30GHz SHF Satellite and space commu- Line-of-sight ionosphere Ionospheric penetration, (super high nication, common carrier penetration extraterrestrial noise, frequency) (CC), microwave high directly
30-300GHz EHF Experimental, government, Line of sight Water vapor and oxygen (extremely high radio astronomy absorption frequency)
103-107 GHz Infrared, visible light, Optical communi~ations Line of sight ultraviolet
Figure s. 1 s Allocation of frequencies in the RF spectrum.
Recommended