User guide

MS-DMT Guide v1.04
Released 05-30-2014
8
PREFACE
The MIL-STD Data Modem Terminal (MS-DMT) application has been developed to provide the
MARS member that cannot afford or otherwise acquire a MIL-STD hardware data modem an
optional means of MIL-STD data modem communications interoperability by using a General
Purpose MS-Windows computer and PC Sound Device as the modem hardware device.
The results from use of this software depend on the user adhering to all recommendations
herein. It is STRONGLY recommended that MS-DMT be the only application running that makes
use of the PC Sound Device and that all directions on configuring and testing your operating
systems latency, sound device sample clock error, setting up the sound device levels and the HF
SSB radio parameters detailed herein be followed to obtain the best possible results with your
equipments. In addition, although optional reading, it is highly recommended that the MARS
member read the “MIL-STD/STANAG Data Modem Primer” document for a good understanding
of military data modem waveforms and their applications.
Those with PC Sound Device Modem (PCSDM) experience from the use of Amateur Radio class
software modem based low symbol rate waveforms commonly used in MARS must NOT make
any assumptions that their existing Windows operating system configuration (or means of
running Windows software using Wine or Winskins or other such utilities under other operating
systems), sound device and levels, HF SSB radio setup or PC-to-Radio interfacing as configured
for Amateur Radio digital communication applications previously used will work properly in
meeting the requirements of this software’s supported Military waveforms.
It must be appreciated that a conventional MIL-STD hardware based data modem has an
accurate and stable sample clock and performs only one function, that of a MIL-STD data
modem. Whereas this software based MIL-STD modem communications tool is being developed
to work within the challenges of the MS-Windows pre-emptive operating system with no
dedicated resources compared the traditional dedicated embedded hardware modem
environment.
The concept of a Software Defined MIL-STD Data Modem running on a General Purpose PC
under the popular MS-Windows or any similar multi-tasking computer operating system as an
economical alternative to expensive MIL-STD software modem system is not without it
challenges in real world application. There are both technical challenges in dealing with any
desktop Computer Operating System (OS) choice as well as the use of a PC Sound Device as the
hardware Modem Device.