Radar Field Analyser - RFA641 Edition Date: 28-Feb-18
4.5. Sectorial DSTC
4.5.1. Theory
The Sectorial DSTC measurement result consists of an RF input power versus time table presented versus
azimuth. To be able to measure the gain vs. time delay, the RFA641 needs to be synchronised to the
interrogation signal of the radar under test.
This measurement is repeated for a number of interrogations in each revolution, depending on the number of
sectors to be measured. The power level for the measurement pulses can be set in the Tx Power control.
Make sure that the power of the measurement pulses is within the Rx range.
The DSTC is implemented after the Rx section, by applying a variable threshold when digitising the video.
Therefore the video level to be sampled for each of the receivers is the quantised video. The Radar Field
Analyser will inject pulses starting from a maximum power level, being decreased each second revolution in
order to retain the threshold voltage vs range and azimuth.
4.5.2. Getting Started
The Sectorial DSTC is loaded from the RASS-S Toolbox using the Rx button.
Make the connections as shown in Annex 6: Sectorial DSTC Calibration Connection Diagram.
Make sure to connect the radar’s interrogation trigger signal to the ACP input connection of the RFA instead
of to the TRIGGER (P1-P3) input. Verify that the quantized video output is connected to the RFA’s video
input.
4.5.3. Software
1. Adjust the settings as needed. Select the correct Tx frequency (default 1090MHz) and set the
Power and the correct Attenuation value. The Power control sets the power level present after the
extra attenuation at the RFA641’s Tx connector, so indicating the power injected in the radars
receiver input. The max. output power of the RFA641 is guaranteed +10dBm at 1090Mhz. The power
level control can be used to manually check the operation of the DSTC.
IE-UM-00165-005 RFA641 User Manual.odt 56/110
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