Amateur RadioDigital Communications A Not So Complicated Overview of Digital Modes and Techniques… Well Kind of Anyway By 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
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
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
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.
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
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
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
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!!
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