120 20170-204a
Paragon
PD
Technical Manual
48
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
I/O Pad P207 (T885), 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 T885 and T855, use above values, for T835 use 1.5kHz (full channel) 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 T885 and 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. If still
failed, contact your Dataradio technical support.
6.4.2.5
RSSI Adjustment (T885 and 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 RV 345 (RSSI level) for T885, RV320 (RSSI level) for T855 to give 2.0V RSSI output at
SK330 pin 2 (T855) or on backplane SK1 pin 5 when measured with a voltmeter (See Figure 28 for
test point location).
-
Vary the RF level and check the RSSI output voltage (Figure 26):
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 26 - T855 and T885, RSSI Curve: volt to dBm
0
1
2
3
4
5
6
7
-120 -110 -100 -90
-80
-70
dBm
Volt
a
g
e
Содержание Paragon
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Страница 64: ...120 20170 204a ParagonPD Technical Manual 56 Figure 31 T885 Receiver Tuning Controls Location...
Страница 65: ...120 20170 204a ParagonPD Technical Manual 57 Figure 32 T881 Exciter Tuning Controls Locations...
Страница 67: ...120 20170 204a ParagonPD Technical Manual 59 Figure 34 T857 Exciter Tuning Controls Locations TCXO...
