Specialized Modem Operation
Modems designed to achieve the highest data rates possible in a radio channel may require a
direct DC connection to the modulation path and the removal of the limiter-filter. In order to
receive FCC Certification, the DTX module must either be tested and approved with a specific
modem connected to the transmitter, or a modulation limiter and limiter-filter must always be
present in the transmit modulator audio path with the modulation inputs AC coupled. To allow for
the most flexibility for the end user, the unit was certified as a stand-alone unit. It is possible, with
hardware modifications and special programming software (not supplied with the unit), to DC
couple the AUX IN input and/or defeat the limiter-filter. The modulation limiter would still be in
place, but the deviation of the DTX module could be set such that the modulation limit within the
DTX module is never reached. The deviation would be set by the modem level and the AUX IN
gain setting. The end user/system integrator would then bear the responsibility of obtaining
certification or operating in a frequency band where certification is not required. Contact RITRON
for details.
Note: Most modems will connect directly to the DTX without requiring any
special modifications or programming.
Antenna Placement
The DTXM module is enclosed in a metal housing for RF shielding. However, RF emitting
sources located very close (less than 12 inches) to the unit can at times affect its operation. It is
not recommended that an antenna be connected directly to the module’s BNC connector unless
the RF output power is set for less than 5 watts or the module is placed within another RF-tight
enclosure.
6
PROGRAMMING
To program DTXM Module, the RITRON PC Programming Kit, DTXM-PCPK-1-M-FIPS, must be
used.
6.1
PC PROGRAMMING KIT
The user should install the programming software on the host computer. The RITRON adapter
cables connect the radio to a computer’s serial communications port. Once the cables are
hooked up, the user runs the programmer software. This program transfers data between radio
and computer memory.
6.1.1
PROGRAMMING KIT CONTENTS AND REQUIREMENTS
The Programming Kit for DTXM Plus radios (via compatible computer) is model DTXM-PCPK-1-
M-FIPS. It includes:
1) Programming Software, DTXM-PCPS-1-M-FIPS.
2) DB-9 to DB-15 connector cable with power cable.
3) 9-Pin to USB Adapter, 2147C002.
The Programmer Kit requires a PC compatible computer with Windows 95 or later operating
system installed. The computer must have a USB port available.
6.2
LOADING THE PROGRAMMER SOFTWARE
Insert the Software disc which contains the programmer in the CD/DVD/CD ROM drive of the
host computer. The program should load automatically. If not, view the contents of the CD ROM
and double click on the install.exe file. Follow the instructions as they appear on the screen. At
the conclusion of the installation procedure, the programming software will be resident on the
user’s host computer.
