User guide

MS-DMT Guide v1.04

Released 05-30-2014

with HF radio communications will offer higher immunity to an RF environment then do

general purpose sound devices in the same cost range. There are many expensive

Outboard professional sound devices that are very well shielded and offer TXCO

referenced sample clocks with many other outstanding features. Outboard devices

should provide reliable operation through 2400bps for MS110A class waveform data

rates. Outboard sound devices should support the higher coded data rates of MS110B

Appendix C and S4539 waveforms when supported in the software.

 HF SSB radios providing USB port based internal Codec (e.g. IC-7200, TS-590 and others)

support via Windows device driver offer native 48kHz sample rate at 16 bit resolution

support with even lower latency, noise and phase jitter than external USB sound

devices. This approach offers an even higher immunity to RF and offers a single cable

interface solution for audio and CAT control. They provide reliable operation through

2400bps for 110A class waveform data rates and should support the higher coded data

rates of 110B Appendix C and S4539 waveforms when supported in the software.

 FlexRadio systems (post SDR-1000) with PowerSDR and Virtual Audio Cable (VAC) and

on board TXCO provide audio in the digital domain utilizing high performance A/D and

D/A converters instead of a conventional Windows driver based PC Sound Device which

results in the most PC stable and cleanest PC digital mode operation possible and

highest RF immunity and thus provides the most reliable support next to a hardware

modem. These systems support 75bps thru 2400bps for 110A class waveform data rates

and will likely support all the higher coded data rates of 110B Appendix C and S4539

waveforms when supported in the software depending on the levels of latency of the

SDR system. For the FlexRadio setup proven to work for MS-DMT see:

http://w3jjj.com/m110a.html and http://groups.yahoo.com/group/MARS_Flexers/

Based on these categories of sound devices, the common range of supported reliable data rates

among all sound device types is 75bps-600bps. Moving away from On-the-Board and Plug-In

sound devices raises the bar to the full range of 75bps to 2400bps for coded MS110A class

waveforms, however the radio’s SSB filter characteristics can also be a limiting factor to

maximum data rate.