Care and Feeding of Telex Radio Dispatch Systems
C-6200 Setup
Phase 4 Design, Inc.
Dave Grant / dgrant@hostnw.net
425.402.7308
11/5/2010 Page 15 of 18
Line Card Transmit Path Adjustment
Once the microphone audio has been digitized, the DSP will first route it through a 2175Hz notch
filter to remove 2175Hz components from the voice. This is done to make sure that no component of
the microphone audio will interfere with the 2175Hz hold tone. At the output of the notch filter the
microphone audio is summed together with the last of the signaling components. From this point the
total transmit audio mix is sent to the DAC and then to the individual output drivers of the Line
Cards.
Transmit Level Adjustment
The transmit level is setup using software potentiometers to adjust the levels of the transmit audio.
Calibration of the TX lines will vary depending on system variables as well as the number of
consoles found in parallel on the line. The tech can use an alert tone set to continuous as a test tone
of given amplitude for this alignment.
Transmit Monitor
The four-wire transmit monitor provides a portion of the transmit audio to the receive path. This
allows the console operator to listen to the transmissions of parallel consoles. To set this level have a
parallel console operator intercom on the line to be set. Adjust R95 (line 1) and R87 (line 2) until the
level is comfortable in the handset/headset earpiece or the speaker.
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