Technical Manual

120 20170-201 Paragon
PD
Technical Manual
47
b) IFR TX frequency to match the main radio RX frequency
c) Filter set to wide band (no audio filter)
d) Select Gen2 (Modulating tone fixed to 1KHz). All other Gen must be off.
e) Set deviation to ±3.0KHz for full channel or ±1.5KHz for half channel radios.
f) Use a X1 scope probe connected to IFR SINAD input and monitor the Discriminator
O/P on the backplane at SK1 pin 6 (RX-audio1). Alternately, it is also possible to
monitor at the receiver TP314 (T855) or at the receiver IC350 pin 7 (T835)
2. Lower the RF level to get a 12dB SINAD reading. Level must be better than -110dBm
(including cable loss).
3. Offset the IFR TX frequency 2kHz (full channel) or 1kHz (half channel) above the main
radio RX frequency, record the SINAD reading. It should remain within 1dB from the on
frequency SINAD reading. For T855, use above values, for T835 use 1.5kHz (full chan-
nel) or 0.8kHz (half channel).
4. Offset the IFR TX frequency 2KHz (full channel) or 1kHz (half channel) below the main
radio RX frequency, record the SINAD reading. It should remain within 1dB from the
on-frequency SINAD reading. For T855, use above values, for T835 use 1.5kHz (full
channel) or 0.8kHz (half channel).
Note: If one of the above requirements is not met, try to re-tune the front-
end. It still failed, contact your Dataradio technical support.
6.4.2.5 RSSI Adjustment (UHF: T855)
- Apply an on-channel signal from the RF generator at a level of -110dBm modulated by a one
kHz tone at a deviation of ±3kHz (full channel) or ±1.5kHz (half channel).
- Adjust RV320 (RSSI level) to give 2.0V RSSI output at SK330 pin 2 or on backplane SK1
pin 5 when measured with a voltmeter (See Figure 30 for test point location).
- Vary the RF level and check the RSSI output voltage ( Figure 28):
1) At –120 dBm: 1.2 VDC (+0.20 –0.45VDC)
2) At –90 dBm: 4.0 VDC (+0.20 –0.20 VDC)
3) At –80dBm: 5.0 VDC (+0.20 – 0.35VDC)
If the requirement cannot be reached, contact your Dataradio technical support.
Figure 28 - T855 and T885, RSSI Curve: volt to dBm
0
1
2
3
4
5
6
7
-120
-110
-100 -90
-80
-70
dBm
Voltage