Vaisala RVP900, Руководство пользователя

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A.22 Checking Calibration and Dynamic
Range
Test Goal
Verify the receiver dynamic range is in excess of 80 dB.
This test requires the injection of an RF test signal over a 100 dB range.
Damage to the LNA could occur. Check the LNA specification to verify the maximum
signal that it can accept. The do not allow the output from the signal generator
(accounting for cable and coupler losses) to exceed this value.
CAUTION!
To avoid damage to the RVP901 (IFDR), do not increase the signal generator
power such that the
Total Power
exceeds the
Safe Total Power Limit
for the
Pr
command display more than +12dBm.
CAUTION!
Test Equipment
KVM connected
RF signal generator
Test Procedure
1. Run the radar and test signal generator for 20 minutes to allow proper warm-up of the
system prior to the test.
This allows the AFC to stabilize.
2. Turn the radiate off, but leave the receiver on since the test signal generator may be
damaged by the transmitter.
3. Elevate the antenna to >20° and point the azimuth away from any known microwave
sources including the sun.
4. Use the setup terminal to enter the calibration gains, losses, and transmit power values.
5. Enter the TTY setups through
dspx
.
6. Use the
ps
command in the dspx utility to put RVP900 in manual AFC control by
pressing
=
.
7. Connect the test signal generator to inject a signal at RF ahead of the LNA.
8. Press % to select the IF input under test.
9. Set the signal generator to a value that is approximately 20 dB above noise and
observe the scope plot.
10. Adjust the frequency of the test signal generator to make the frequency of the
spectrum to the correct IF frequency.
You can also do this by using
Pr to monitor the Filtered reading and selecting the
frequency setting with the highest dBm reading.
Filtered : ________dBm
RVP900 User Guide M211322EN-J
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