Appendix C _____________________________________________ Installation and Test Procedures
VAISALA______________________________________________________________________ 389
C.22 Receiver Bandwidth Check
Test Goal
Verify the receiver bandwidth is in excess of 14 MHz.
Background
For proper functioning of the high speed A/D convertors, it is necessary
that approximately 14 MHz of broadband noise is available at the RVP900.
This noise does not interfere with the signal to noise ratio because the
bandwidth filter is applied afterwards. The bandwidth of the anti-aliasing
filter should be the limiting factor. This test uses the same hookup as the
previous test (Section C.21 Calibration and Dynamic Range Check on
page 381). For dual polarization systems, you expect to get a narrower
bandwidth.
Special Test Equipment
- KVM connected
- RF signal generator
Reference
-See Section 5.5 Pr — Plot Receiver Waveforms on page 163
Test Procedure
1. Connect the test signal generator to inject a signal at RF ahead of the
LNA.
2. Enter the Pr mode and make the following settings:
- Use the space bar to toggle to the power spectrum plot.
- Use the L/l and R/r commands to set the start to 50 usec.
- Use the T/t command to set the plot span to 50 usec.
- Use the V/v command to set averaging to 1 sample.
3. Set the signal generator power to a value that is approximately 60 dB
above noise and observe the scope plot.
4. Adjust the frequency of the test signal generator in 1 MHz increments
to cover the whole range of the scope plot. Mark the total power
measured on the plot in Figure 62 on page 384.
5. Verify that the 3dB point gives approximately 14 MHz of bandwidth.
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