Appendix C _____________________________________________ Installation and Test Procedures
VAISALA______________________________________________________________________ 391
C.23 Receiver Phase Noise Check
Test Goal
Verify the stability of the STALO by looking at the phase noise of a clutter
target.
Background
For proper velocity calculations and for ground clutter rejection, it is
required that the radar's STALO maintain a stable frequency, and that the
transmitted pulse contain no amplitude or phase artifacts.
Special Test Equipment
- Ascope utility (refer to the IRIS Utilities Manual)
- Known clutter targets with no weather signal
Test Procedure
1. Configure the radar for normal operation expect pointing at a known
clutter target.
2. Run the ascope utility and configure as follows:
- 16-bit time series
- Spectrum not from DSP
- Spectrum size 256
- Rectangular window
- Short pulse width
-High PRF
- No clutter filters
3. Select the maximum range and number of bins to get the maximum
resolution over the target. For targets < 24 km, use 201 bins, 25 km.
4. Select the range bin of the target. Record the Az, El, range and phase
noise:
Az:______ El:______ Range:______ Phase Noise:______
Az:______ El:______ Range:______ Phase Noise:______
Az:______ El:______ Range:______ Phase Noise:______
Az:______ El:______ Range:______ Phase Noise:______
Az:______ El:______ Range:______ Phase Noise:______
Az:______ El:______ Range:______ Phase Noise:______
5. Try minor changes in Az, El, and Range to get the lowest phase noise.
The goal is less than 1 degree within 20 km.
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