Line in adjustment, Tx mod adjustment – CPI Communications TTP(N) Series User Manual
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Line In Adjustment
Auto level adjustment:
The TTP(N) series has an AGC (automatic gain control circuit). This circuit eliminates the need to adjust the
line input level from the tone remotes or consoles. Selection of automatic or manual gain control is selected by
the JP2 jumper.
Automatic gain control - JP2 should be set in the 1&2 position.
Manual gain control - JP2 should be set in the 2&3 position.
The line input level is adjusted via R104. Adjustment should be made with the TTP(N) connected to the phone
line and a tone remote connected at the far end.
Follow the procedure for your remote to generate a constant function tone. Ideally the function tone will mea-
sure 0 dBm on the phone line at the remote site. The function tone level measured across the phone line at the
TTP(N) will usually be less than 0 dBm due to line loss.
With an RMS voltmeter measure the signal level from test point 4 (TP4) of the TTP(N) to ground. Adjust R104
for a reading of 460 mVrms (1.3Vpp)
Note: If you are using the hold tone (low level guard tone) to make the adjustment, set R104 so that 46 mVrms
(130 mVpp) is measured at TP4. If you are using the high level guard tone to make the adjustment, set R104 so
that 1.49 Vrms is measured at TP4.
TX Mod Adjustment
This section assumes that each remote in the system has been set to provide an average voice audio level of
0 dBm measured at the remote. Have someone at the remote console press and hold the PTT switch. With a
voice coming from the remote, adjust R102 to provide proper transmitter deviation.
Monitor Adjustment
The monitor function can be used in one of two modes:
Momentary mode: (JP12 in position 2 &3) - The monitor relay energizes for approximately 6 seconds or until a
PTT command is received.
Latched mode: (JP12 in position 1 & 2) - The monitor relay stays energized until a valid PTT command is
decoded.
Note: Some radios require that the monitor circuit be activated while keying. This can be accomplished by
shorting pins 2 &3 of JP11.
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