18 Calibrating the Reciter © Tait Electronics Limited February 2007
7. Calibrate each of the frequencies shown. Follow these steps.
a. Click the option button alongside a frequency.
b. If the modulation meter cannot auto-tune, set its frequency to the
selected value.
c. Using the Fine and Coarse arrows, adjust the slider until the deviation
shown on the modulation meter is 3000 Hz (peak).
d. Repeat steps a) and b) until all frequencies for the band are calibrated.
This enables the Next Band button.
8. Click Next Band and repeat steps 4) through 6). Repeat until all
frequencies in all bands have been calibrated.
9. If you are connected to a K-band reciter, click Next. Select one of the two
sub-bands. This
determines the sub-band that is displayed on CSS monitoring
screens and that has its lock range determined in diagnostic tests. However,
exciters can always operate on frequencies in either sub-band.
10.Click Finish. (If you are using a PA, it will now stop transmitting.)
When you have finished calibrating the VCO, the icon on the Reciter
Calibration tab indicates that this task is complete.
You should now adjust the exciter lock band because it was re-tuned several
times during this procedure. This means that the exciter is no longer on the
required frequency. If you have P25 test equipment, we also recommend that
you carry out a modulation fidelity test to verify the adequacy of the FCL and
VCO calibration for digital P25 transmissions.
Calibrating the RSSI
Calibrating the RSSI (received signal strength indicator) ensures that the
reciter's internal RSSI values accurately reflect the actual received signal
strength. Changing the receiver's lock band can alter the calibration accuracy by
about 1 dB.
Note: Ensure that the receiver’s lock band has already been adjusted
to the required setting before carrying out this procedure. (See
“Adjusting the Receiver Lock Band” on page 8.)
Equipment ■ RF signal source
Setup
To calibrate the RSSI
1. Make sure that the equipment is set up and that the Calibration Software is
connected to the reciter.
1
2
1 RF signal source
2 Reciter
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