Amateur RadioDigital

CommunicationsA Not So Complicated

Overview of Digital Modes and Techniques…

Well Kind of AnywayBy Bill Richardson, N5VEI

What is “Digital Mode”?Major Digital Modes

• CW – Technically you are manipulating 1’s and 0’s to make a message

• PSK – Various speeds, reliable• RTTY (ASFK, FSK)• MSFK• Pactor – Booo, hiss hiss, feel the anger!!!

Minor Digital Modes• Hellschreiber - Fax based• Throb – 1, 2, or 4 tones per second• MT63 – Sounds like static or alien

communications, and really wide spectrum• JT65A – Slow, short communications• Olivia – Really wide spectrum, often confused

with MSFK in sound and appearance

Why digital?• Puttin’ the hammer down! - Without an amp

that is. More efficient than the ups and downs of a voice communication. Usually a constant or better average power output on most modes

• You can piece together QSO’s easier from observation

• Helps the hearing impaired• Efficient spectrum use – squeeze everything out of

limited space• ALL modern DIGI modes are done in USB regardless

of the band

Sounds – Yes it is a TEST If you fail, you will have bodily disfigurement

Equipment Needed• Preferably a modern rig with CAT capability• Soundcard Interface – one with tx and rx

adjustments• Computer• Cabling – USB preferred

Interfaces and other Equipment

It can as complicated as YOU want

No… I don’t think so….

Common Digital Software• Free – Ham Radio Deluxe DM780 bundle,

Digipan, DXLabSuite, MM software such as MMSSTV, HamScope (may be free ??), FLDigi

• Pay – MixW, Stuff from MFJ, many others – Beware!

• Free Is always BETTER - every time!

Ham Radio Deluxe/ Digital Master

• http://www.ham-radio-deluxe.com/• Biggest advantages– 1st - IT IS FREE… Say it AGAIN…. FREE– 2nd - Very diverse in what you can do with the

program (both HRD and DM780)– 3rd – Supports cat control of most modern rigs, but

works with most anything as well

HRD Screenshot

DM780 Screenshot

MixW

Waterfall vs SpectrumPSK

Waterfall vs. SpectrumPSK

Waterfall vs. SpectrumDon’t be shy

Try to ID the signal

Waterfall vs. Spectrum

And the signal is- PACTOR

This is why you need both spectrum AND waterfall capabilities!

Major MODE - PSK

• Good – efficient, many users, software is everywhere a little goes a LONG WAY

• Good – Comes in at least 3 baud rates

Disadvantages• PSK – has a few MAJOR disadvantages• OVERDRIVEN SIGNALS !!!!!!!! • Not as many operators – but growing really fast!• Setup can be difficult• Understanding your own software and setup!• Most of all it is hard to get use to the common

practices and identify modes. Ex. – where to use modes and for what purpose (40 meter PSK)

Major PSK concepts• DO NOT HAVE ANY ALC --- AT ALL!!!!!!• Turn off your processors!• The bad results of both not being done are as follows• Run only as much power as needed – But again…

ALWAYS monitor your ALC• Use your filters to know out bad signals

Normal PSK QSO with Estonia

RTTY – Good Ole’ Stand BY

• Two types – FSK (the original) and AFSK (soundcard based)

• VERY reliable and is used by lots of people world wide

• Relies on shift and parity• As in all modern DIGI modes, ASFK is USB

unlike traditional FSK being in LSB or USB.

RTTY Image

MT63 – Sounds like Aliens

MT63• Used for reliable communications• Can take up lots of spectrum• You do not have to hear it to decode it!• Hard to get setup to receive with different

software• Great for short data transfer – ex. tactical or

emergency traffic when conditions are bad.

THROB – NO, not your heart• It uses 1, 2, or 4 tones/throbs per second • Sounds really cool• Not really reliable as others• Hard to line up with the traces

Hell !!!!!! No, not the hot place …. Just the FAX mam.

Continuing HELL, Hellschreiber that is

• Old mode that came out of War• It is a FAX mode• Sounds like scratchy CW or a Scratchy Cricket• Several different types of Hell exist – different rates

as well as mode (ex. Feldhell, FM hell, PSK hell)• Very fun mode to mess around with

Interference from HELL

Olivia – Wide and Proud• Great for harsh conditions when you need to be

heard – GREAT weak signal!!!!• You do not need to see the signal or even hear it

for the decoding process. Hard to line up the traces. If not exact… you get NOTHING!

• Sounds VERY similar to MSFK• Comes in different numbers of tones as well as

width to accommodate customary uses (yeah right!)

JT65A – To the moon my son!• JT65A – originally used for EME

communications• VERY short text – really for confirmation only.• Coordinated with UTC time – Your computer

MUST be synchronized with UTC• Long varying pitched tones

JT65A Current uses• Used on HF and 6 meter bands for DX• Cannot support long of even mid level QSO• WSJT is the standard program used

• http://www.physics.princeton.edu/pulsar/K1JT/• Hard to configure• Works best with a dedicated soundcard interface and

computers that have free comm ports 8 and below

JT65A - Image

Controversy in Digital Realms• CW Skimmer• http://www.dxatlas.com/CwSkimmer/• Controversy – you can observe hundreds of

QSO’s in progress.• Is it legal in contests? ARRL? Yes, but they do

not like it!!!• Pile up buster!!

CW Skimmer Images

If CW Skimmer is controversial… then what about this?

Sources of Info and Questions• http://www.wb8nut.com/digital.html• http://mars.superlink.net/~driller/• www.ham-radio-deluxe.com• www.dxlabsuite.com• www.mixw.net• http://www.rac.ca/opsinfo/infodig.htm• www.arrl.org

If your brain now hurts… you learned something… It is just a steeper learning curve than

other modes