Radar Field Analyser - RFA641 Edition Date: 28-Feb-18
4.1.3. Software
Once the tool is running, the calibration pulse is shown in the Calibration Pulse graph. As long as no
calibration procedure has been started, the tool is in “free run” mode. This means that all parameters can be
changed on the fly and their impact on the measurement is shown directly in the calibration pulse graph.
Move the slider under the display to change the transmission power of the RFA641 and see the impact on
the display.
The output voltage is measured by calculating the mean, max or RMS value of the part of the output pulse
selected by the cursors. Therefore it is important to position the cursors correctly. If the measured part
between the cursors is not flat (spikes, noise) a beep is produced and the graph will turn red. This does not
mean that the calibration is wrong, but that some points in the calibration curve can be erroneous.
1. RF Section: Set the correct Extra Attenuation value. This value depends on your receivers input
range. The output power of the RFA641 for calibration is guaranteed +10dBm at 1090Mhz. If for
example the maximum receiver input power is -20 dBm, the external attenuator should be 30dB in
order to reach the maximum receiver input power. In most cases, the calibration will be performed
through a coupler which is fixed in the antenna chain, typically 20dB or 30dB. This value must also
be taken into account. The value of the input coupling factor of the coupler in the receiver chain plus
the value of the extra attenuation must be entered in the control.
Set the Power Step value to be used. This value will determine the step in transmission power used
by the RFA641 to perform the calibration. A typical value of 0.1 dB is sufficient.
Set the RFA Tx frequency to be used for calibration. For (M)SSR radars this is always 1090MHz. If
a PSR radar is to be calibrated, set the RFA Tx frequency to the PSR operating frequency.
2. Triggering Section: The receiver calibration is performed at a certain time delay after the
interrogation trigger pulse: be sure to set the Delay after Trigger value. If the calibration is
performed without applying a trigger pulse, the calibration will use a fixed calibration PRF determined
by the Timeout parameter (PRF=1/Timeout).
Set the Pulse Width of the calibration pulse.
Note: When a PSR receiver is being calibrated: make sure the pulse is outside the STC of
your receiver by changing the Delay after Trigger parameter.
3. All measurements included in the radar receiver measurements rely on the Radar Field Analyser
hardware, especially on its transmitter. In order to verify its behaviour and calibrate the transmitter
output power, a selftest function is included in all the programs using the RFA641 transmitter
hardware. If you want to verify the operation of the RFA641, click the Cal RFA button before
proceeding with the Receiver Calibration.
4. Verify the correct connections as shown in the connection diagram and click the Sum button.
5. A dialog box will prompt the user to check the connections of the different channels to the back panel
Ch 2(in) and the Tx of the RFA641. Confirm the connections by clicking the OK button.
IE-UM-00165-005 RFA641 User Manual.odt 44/110
To Next Page
Loading...