User guide

MS-DMT Guide v1.04
Released 05-30-2014
11
The MS-DMT baselines also serves as the basis for Research and Development (R&D) in pursuit
of improved 110A serial tone modem development and additional MIL-STD and STANAG
waveforms in support of MARS. Already a more advanced Metric Inversion Equalization (MIE)
based MS110A modem vs. the existing Decision Feedback Equalization (DFE) MS110A modem
and an STANAG 4285 based modem are under in development.
In conjunction with a properly configured computer system and viable sound device and
properly configured HF SSB transceiver as detailed herein, the MS-DMT software supports basic
FEC based ASYNC (with EOM) or SYNC (with or without EOM) modes interoperable with
hardware modems for FEC based ASCII message communications using the internal terminal or
an external terminal application via the data port. Also supported is an asynchronous serial port
High Speed ASYNC mode which is SYNC (with EOM) Over The Air (OTA) compatible which
supports transparent (when TRANS is checked) data port external communications applications
in support of binary data streams such as Data Link Protocol layers. To communicate with
hardware modems via any SYNC selection in the MS-DMT requires the hardware modem used
to be wired to an RS-232 Synchronous port and placed into SYNC mode or wired for RS-232
Asynchronous and placed into “High Speed ASYNC” mode if provided by the hardware modem.
High Speed ASYNC is usually only found in 110B.class hardware modems.
This software has been tested against various make/model MIL-STD hardware modems under
dumb terminal control for FEC operation using the hardware modems operating in ASYNC or
110B class “High Speed ASYNC” (SYNC compatible over the air (OTA) mode) modems using 110A
and found to be 100% compatible. In addition the same external terminal software applications
have been used with both the hardware modem and the MS-DMT via the MS-DMT external data
port in testing where the MS-DMT has been found to perform properly with these terminal
programs. In addition test software has been used with hardware modems in High Speed ASYNC
to test TRANS mode where binary data has been send and received.
The 110A ST waveform and other MIL-STD/STANAG waveforms perform best with an HF SSB
100w or greater (where 400w plus for CONUS broadcasting is recommended) RF output radio
having a Temperature Compensated Oscillator (TXCO) and IF passband of 2750Hz (nominal
Military 3kHz bandwidth) at the 2 dB points with low group delay as detailed in STANAG 4203
(and the radio performance specifications detailed in MIL-STD-188-141C
[9]
) which specifies the
properties of military radios which receives the bassband audio signal (3 kHz bandwidth)
from the modem and modulates it onto a carrier.
At present, the bulk of MARS members will likely be limited to about 600bps in 110A ST
operation for consistent results, this is largely due to their radio filters not meeting S4203