Product Info

PTR for VHF-4000 and VDL-2000 Data Radios
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©2000 Rockwell Collins, Inc Page 17 of 61
5) Increment TFM parameters # 18 until the RF wattmeter indicates 19.5 watts +/- 1
watt.
6)
Unground the PTT.
7) Store the values for TFM parameters #17 and 18 in Flash memory.
6.3.9 Simulcomm 0 Adjustment (-20 dBm threshold) [Rx TFM]
1) Set Standard ARINC Configuration at current frequency.
2) Set Standard RF Generator setting at current frequency.
3) Set Standard Discrete Configuration.
4) Set rear connector simulcomm discretes to 00 (VHF4000 Pins 42 and 46 open, VDL
Pins 16 and 34 open).
5) Set the generator RF level to -20 dBm and 90% modulation.
6) Monitor the AGC_Level output of the RF Card.
7) Decrease TFM parameter # 3 until the AGC_Level decreases at least 2% - 4% from
the reading in step 6.
8) Store the value used for TFM variable #3 in the Flash memory.
9) Find value at 118 MHz channel and use value for 119-125 MHz channels.
10) Find value at 126 MHz channel and use value for 127-136 MHz channels.
6.3.10 Simulcomm 1 Adjustment (-10 dBm threshold) [Rx TFM]
1) Set Standard ARINC Configuration at current frequency.
2) Set Standard RF Generator setting at current frequency.
3) Set Standard Discrete Configuration.
4) Set rear connector simulcomm discretes to 01(VHF4000 Pins 42 open and 46
ground, VDL Pins 16 open and 34 ground).
5) Set the generator RF level to -10 dBm and 90% modulation.
6) Monitor the AGC_Level output of the RF Card.
7) Decrease TFM parameter # 4 until the AGC_Level decreases at least 2% - 4% from
the reading in step 6.
8) Store the value used for TFM variable #4 in the Flash memory.
9) Find value at 118 MHz channel and use value for 119-125 MHz channels.
10) Find value at 126 MHz channel and use value for 127-136 MHz channels.
6.3.11 Analog Voice/Data Transmitter Modulation [Tx TFM]
1) Set Standard ARINC Configuration at current frequency.
2) Set Standard Discrete Configuration.
3) Apply a 0.4 Vrms audio signal at 1.0 kHz to the microphone input.
4) Ground the PTT and simultaneously increment TFM parameters #23 and 24 (AM I
and Q Channel Mod) to obtain modulation of the negative peaks at 90 +/- 3 %.
5) Unground the PTT.
6) Store the value used for TFM parameters #23 and #24 in the Flash memory.
6.3.12 Simulcomm 2 Adjustment ( 0 dBm threshold) [Rx TFM]
1) Set Standard ARINC Configuration at current frequency.
2) Set Standard RF Generator Setting at current frequency.
3) Set Standard Discrete Configuration.
4) Set rear connector simulcomm discretes to 10 (VHF4000 Pins 42 ground and 46
open, VDL Pins 16 open and 34 ground).
5) Set the generator RF level to 0 dBm and 90% modulation.
6) Monitor the AGC_Level output of the RF Card.