Product Manual for Tornado X and Tornado XR
31
7 RSSI CALIBRATION
7.1
RSSI
C
ALIBRATION
The Receiver RSSI may need be re-calibrated once the frequency of Transmitter and Receiver is swapped and
the duplexer T/R end has been swapped.
A signal generator (analog) like Agilent E4432B or similar ones can be used for the RSSI calibration. And a 30dB
attenuator (best to have 30W power handling) should be used in between the signal generator and the Radio RF
port.
The RSSI and AGC control voltage are in linear relationship, as shown in formula 1.
RSSI = A x Vagc + B
(1)
Where A represents the slope of the curve and B is the offset.
NOTE
: The RSSI reading has an uncertainty of +/- 1.5dB
To find out A and B value we need two points (RSSI1, Vagc1) and (RSSI2, Vagc2), which are obtained by applying
-40dBm and -60dbm signal at the receiver and recording the AGC voltage respectively.
RSSI calibration can be easily achieved by following the instructions step by step. Below is the summary of the
procedure that is also shown on the RSSI Calibration page below (Calibration > RSSI Calibration).
1. Connect signal generator via a 30dB attenuator to Channel 1 RF port (receiver 1).
2. Set signal generator level so that -40dBm can be measured at the receiver input. Choose un-modulated
carrier for the input signal.
3. Select Rx1 in the CCMS page.
4. Select -40dBm in the CCMS page.
5. Click Read in the CCMS page.
6. Set signal generator level so that -90dBm can be measured at the receiver input.
7. Select -60dBm in the CCMS page.
8. Click Read in the CCMS page.
9. Click Calculate in the CCMS page.
10. Set signal generator to -40dBm.
11. Click Calculate Offset in the CCMs page.
12. Click Save in the CCMS page.
13. Connect signal generator via a 30dB attenuator to Channel 2 RF port (receiver 2).
14. Repeat Step 2 to 12 for the Channel 2 receiver.
15. The following message will appear. Click
apply
to apply the new RSSI calibrations to the radio.
a.
