Product Info

PTR for VHF-4000 and VDL-2000 Data Radios
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©2000 Rockwell Collins, Inc Page 19 of 61
13) Reduce the RF generator output by 4 dB.
14) Decrease calibration parameter #8 (8.33 kHz noise squelch mute threshold) from
$03FF until the receiver audio is muted (0.0 to 0.049 Vrms).
15) Store the values for calibration parameters #8 and #9 in flash memory.
6.3.14.3 CARRIER SQUELCH
1) Set the UUT discrete inputs to “standard discrete configuration”.
2) Set the generator to 60% modulation by 6 kHz at –94.5 dBm.
3) Disable noise squelch by setting TFM #8 & #9 to $FFFF (Do not change values in FLASH)
4) Monitor the receiver audio output.
5) Increase value of calibration parameter #5 (carrier squelch unmute) from $0000 until receiver audio is
present (0.05 to 2.6 Vrms).
6) Reduce the RF generator output by 5 dB. Decrease calibration parameter #4 (carrier squelch mute) from
$FFFF until the receiver audio is muted (0.0 to 0.0245 Vrms).
8) Store the values for calibration parameters #4 and #5 in FLASH memory.
6.3.15 Mode A Alignment (Units/w Mode A Option Only)
6.3.15.1 MODE A RECEIVER
None
6.3.15.2 MODE A TRANSMITTER
Reserved
6.3.16 Mode 2 Alignment (Units/w Mode 2 Option Only)
6.3.16.1 MODE 2 BIAS ADJUSTMENT
1) Set the UUT discrete inputs to “standard discrete configuration”.
2) Set the ARINC data to “Standard 25 kHz ARINC Configuration” on channel 118.500.
3) Connect 50 ohm load to antenna cable
4) Set TFM parameters #18 and 19 (D8PSK I and Q channel offset) and #15 and 16 (D8PSK Channel
Gains) to $00 to set transmitter power to 0 watts.
5) Set TFM parameters #12 and #14 (PA drive bias and final driver bias) to $0000.
6) Ground the PTT (VHF-4000 pin 41, VDL-2000 pin 35), and monitor the input current to the UUT.
7) Adjust TFM parameter #12 until the current increases by 500 mA ± 50 mA over the original value.
8) Adjust TFM parameter #14 until the current increases by an additional 1500 mA ± 50 mA over the
value in step 5.
9) Unground the PTT.
10) Store the values used for TFM parameters #12 and #14 at 118.500 in 18 FLASH memory location up
to 136.500 MHz for the VDL-2000 and 151.5 MHz for the VHF-4000.
6.3.16.2 MODE 2 CARRIER NULL
1) Set the UUT discrete inputs to “standard discrete configuration”.
2) Tune the UUT to Channel 118.500.
3) Set TFM parameters # 15 and 16 (D8PSK I_Channel Gain and Q_Channel Gain) to $00.
4) Set TFM parameters # 18 and 19 to mid-scale: $800.
5) Ground the PTT line (Pin 41 VHF-4000, Pin 35 VDL-2000), and adjust TFMs # 18
and 19 (I_Offset and Q_Offset) alternately to null the carrier as detected on a
selective measuring receiver or power meter. The null shall be less than -15 dBm at
the sampled port.
6) Unground the PTT line.