23 Calibration tests Tuneup
August 2004 © Tait Electronics Ltd
1) Provide a unmodulated RF input signal at greater than -20dBm from an
accurate (< 0.1ppm) RF signal generator, set to the test frequency identified
below.
2) Click the 'Calibrate' button.
3) From the toolbar, click Accept button (green tick) to save changes or
Reject (red u-bent arrow) to cancel.
3.3 Receiver
The front end (FE) tuning voltage sets the centre of the bandpass filter in the
receiver section of the radio. The received signal strength indicator (RSSI)
must be calibrated to give an accurate measurement of received signal
strength.
The automatic gain control (AGC) is used to adjust the radio’s gain in
relation to various power levels. The AGC will begin to reduce gain when
the combined signal power of the wanted signal and first adjacent channels
is greater than –70dBm approximately. The calibration test is run at
-68dBm, -60dBm and -50dBm for standard TM9000 radios.
1) Connect a signal generator and prepare it to generate a signal on the first
frequency identified in the test frequency box, with the power to the level
indicated in the Signal Input Level box, with 3kHz deviation, and a 1kHz
modulated tone; then turn the RF signal on.
2) Click the 'Calibrate' button.
3) Increase the power level to the new power level identified on the Signal
Input Level box. Do not increase it past this value, then wind the signal
generator power back down; if you overshoot, you will need to repeat the
test from Step 1.
4) Click the 'Calibrate' button.
5) Increase the power level again to the new power level identified on the
Signal Input Level box. Do not increase it past this value then wind the
signal genorator power back down; if you overshoot, you will need to repeat
the test from Step 1.
6) Click the 'Calibrate' button.
7) Increase the power level again to the new power level identified on the
Signal Input Level box. Do not increase it past this value, then wind the
signal generator power back down; if you overshoot, you will need to repeat
the test from Step 1.
8) Click the 'Calibrate' button.
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