User guide
MS-DMT Guide v1.04
Released 05-30-2014
16
CURRENT M110A DMT FEATURES
PC Sound Device for selection is provided by both Name and Number with no need to
shutdown and restart the software.
Supports multiple USB 2.0 or greater devices of the same or different make/model for
clean selection. Where for example, if using two Signalink USB devices, the 2nd device
shows up as "USB Codec 2".
Provides automatic sample clock error correction that may mitigate 75ppm sample clock
error when monitoring a hardware modem based stations transmissions. However,
overall sample clock error of less than 20ppm is required for good results, less than
10ppm is required for excellent results with 1ppm or less sample clock error providing
the best performance. Sample clock error is accumulative between stations, for
example, if station A has +10ppm error and station B has -10ppm error, the overall error
is 20ppm.
MIL-STD-188-110A standard 1800Hz PSK carrier is used by default. However optional
PSK carrier selections used in many hardware modems of 1650Hz and 1500Hz are also
provided where the use of the optional PSK carrier to center signals within narrower SSB
filters must be offset from the dial frequency of stations using 1800Hz by the difference.
The MIL-STD-188-110A symbol rate is fixed at 2400bps requiring 2.7kHz IF filters
minimum to meet full performance specifications. Less than 2.7kHz BW filters will
impede the performance of data rates higher than 600bps.
An external Data Port is provided in support of 3
rd
Party Applications for two-way
communications via an RS-232 serial port for data, but not remote control at this time.
The Data Port defaults at 19,200 baud with fixed parameters of 8N1 and CTS/RTS
handshaking. Any baud rate from 1200 to 240,000 is supported for selection.
Communication port support is limited to COM1..COM16 at present. The DTR line is
asserted to indicate an active PTT state. The Data Port supports RS-232 Asynchronous
interfacing providing both ASYNC and compatible SYNC Over-the-air (OTA) operation.