Product Info

PTR for VHF-4000 and VDL-2000 Data Radios
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©2000 Rockwell Collins, Inc Page 29 of 61
1.2.8.1.1. AUDIO OUTPUT DISTORTION
1) Set the UUT discrete inputs to “standard discrete configuration”.
2) Apply a –54 dBm signal at 126.600 MHz, modulated 80% at 1 kHz.
3) Set the ARINC control data to “Standard 25 kHz ARINC Configuration” on channel 126.600.
4) Adjust the distortion analyzer connected to the combined audio output (VHF-4000 pins 25 and 26,
VDL-2000 pins 33 and 19 ) and measure audio distortion.
Production Limit:
Audio distortion: <= 5%
CMM Limit:
Audio distortion: <= 7%
1.2.8.1.1. RX AUDIO COMPRESSOR
1) Set the UUT discrete inputs to “standard discrete configuration”.
2) Apply a –54 dBm signal at 126.600 MHz, modulated 50% at 1 kHz.
3) Set the ARINC control data to “Standard 25 kHz ARINC Configuration” on channel 126.600.
4) Verify the audio output level.
5) Increase the modulation depth to 90% and note that the change in combined audio output level.
Production Limit:
Audio variation: <= 1 dB.
CMM Limit:
Audio variation: >= 3 dB.
7.2.1.9 SELCAL AUDIO OUTPUT (VHF-4000 ONLY)
1.2.9.1.1. OUTPUT LEVEL
1) Set the UUT discrete inputs to “standard discrete configuration”.
2) Set the RF Generator to “standard RF generator configuration” at 126.600 MHz.
3) Set the ARINC control data to “Standard 25 kHz ARINC Configuration”.
4) Apply -54 dBm signal at 126.600 MHz, modulated 60% at 1 kHz to the antenna port.
5) Verify the SELCAL audio output level at the combined audio output (pins 38 and 37)
Production Limit:
SELCAL audio output: 1.0 +/- .2 Vrms
CMM Limit:
SELCAL output level: 1.0 - .3 Vrms