There are many digital modes available for use by today’s ham radio enthusiast. These include RTTY, PSK31, PSK63, Packet, Pactor, Hellschreiber, Picillo , SSTV and WSJT amongst others. The most recent addition to the diigtal modes is ROS.
Digital communications predate the personal computer by many years but for the purpose of this web page, digital modes will be considered to be those traditionally encoded and decoded electronically. Currently the use of PC sound cards to encode and decode digital signals has become the ham radio standard.
The digital modes are primarily low power, narrow bandwidth modes. My interests revolve around RTTY, PSK31 and MFSK.
RTTY is the oldest of the digital modes, and whilst it does not support the features of the newer data modes, it is better suited to roundtable QSO’s with several stations. It is also the most popular mode for worldwide digital contest events.
PSK31 is particularly effective for low power (QRP) operation. It uses phase-shift keying techniques, usually generated by PC based software operating through a PC soundcard. As with all the digi modes, a simple interface is used to link the PC to the radio transceiver.
MFSK is a system where individual pulses of different radio frequencies carry information, and the data carried depends on the frequency of the pulse. This is the same as FSK, for example radio teletype (RTTY), but rather than two different tones, many more are used - from six to 64, for example. MFSK16 uses 16 tones. Each tone transmitted is just like a Morse code dot, but they follow each other without pause, on slightly different frequencies.
For detailed information on each of these modes please refer to the relevant RSGB and ARRL publications or click here.
The digital modes may be operated using a variety of programs. I use MMVARI (which comes with Logger32) but
Digital Master 780, a software program closesly associated with Ham Radio Deluxe, is also worth exploring. It offers a wider range of operating modes than MMVARI and can be directly linked to Logger32 (via a DM780/Logger32 interface and HRD virtual port connection). This link means that all QSO's made using DM780 are automatically recorded in Logger32. Guidance on how to establish the HRD virtual port connection is available in pdf format
here.
In December 2008 I discovered Fldigi.exe. This comprises a suite of digi mode programs suitable for use by ham radio enthusiasts. It offers a range of digi modes similar to those available on DM780 and MixW and is easily linked (more so than DM780) to Logger32 for logging purposes. It is simple and straight forward to use and easy to configure. Links to the download site for Fldigi are shown below but after downloading and before installing, make sure you study the relevant read-me files.
Finally, a new digi mode has appeared recently. Based on the already well known Winmor, A4 Chat uses both FEC and ARQ modes and is likely to be of interest to those who used amtor in the past.
Digital communications are challenging but also great fun to use.
The Logger32-DM780 and Logger32-Fldigi linking programs may be found here as may also the Fldigi.exe program.
Updated 10 October, 2011 09:48:35 GMT