MIL-STD-469B APPENDIX A
40.5.3.1 The spurious emission test should be performed for each radar tuned frequency and operating mode specified for emission bandwidth tests (see 5.3.2).
40.5.3.2 The output power should be measured using a thermal-type power meter and an appropriate signal sampler. The system directional coupler should be used, if available, and should be calibrated over the range of frequencies measured. For phased arrays the output power should be measured as specified in
40.2.33. The number of transmitters selected should be determined using a table of random numbers. Initially fifteen of the transmitters should be selected for measurement purposes. The standard deviation of the measured data should be calculated. If the standard deviation is greater than 2.0 dB, additional transmitters should be measured. The number of transmitters to be measured can be determined using the student-t distribution. The mean of the measured data should be calculated giving the power output per transmitter. The total power output is then the mean power output in watts, corrected for any antenna weighing function times the total number of transmitters.
40.5.3.3 The first part of the spurious emission test procedure supplements the emission bandwidth, as necessary, for defining the power spectral level in the rolloff region. The procedure consists of increasing the spectrum analyzer IF bandwidth to capture more spectral power in frequency regions away from the radar fundamental but with a loss in the detail for the spectrum lobes. The result is an increase in the amplitude of the spectrum envelope relative to the analyzer noise level. A correction factor (k) should be determined for relating the data measured with the increased analyzer IF bandwidth to the data from the radar emission bandwidth test.
40.5.3.4 The second part of the spurious emission test procedure should be applied only when the spectrum analyzer, at maximum IF bandwidth, produces insufficient dynamic range in the measured data; that is, dynamic range is less than the 60 dB or (P t + 30) dB, whichever is required. The second part of the procedure should be required for adequate measurement sensitivity between the end points of the spectrum rolloff regions and the limits of the required test frequency range. In the second part of the test procedure, the spectrum analyzer in the test setup should be replaced with a tunable receiver (frequency selective RF voltmeter, FSVM). A correction factor (k) should be used for relating the data measured with FSVM to radar emission bandwidth data.
40.5.3.5 The spurious emission test should be performed for each radar transmitter tuned frequency and operational mode used in the emission spectrum test (see 40.4).
40.5.4 Procedures. Refer to procedures as shown on figure 10 for a typical block diagram of this test. Tune the radar transmitter to a standard test frequency and most used operating mode. Adjust the output power to the nominal level. Record the measured transmitter power at the start of this test and at intervals of
30 minutes or less (more frequently if a noticeable change occurs). A power meter with a recorder output is desirable to permit recording a sample level of the transmitter radiated power output providing a permanent record of any power fluctuations occurring during this test.
40.5.4.1 The procedure should be described for spurious emissions above the radar tuned frequency (F It should be assumed that the radar emission bandwidth procedure has been completed to a frequency above Fo where the emission level is less than 5 dB above the spectrum analyzer noise level. The analyzer IF
o).
bandwidth should be increased and the frequency sweep range should be tuned for a spectrum display which
overlaps the upper end of the sweep range of the previous spectrum photograph. The overlap region should include amplitudes which are at least 15 dB above the analyzer noise presentation in the previous photograph. The results from the process of changing the bandwidth and overlapping sweep ranges should be as shown on
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