MIL-STD-469B APPENDIX A
Receiver intermediate frequency (F ): 30 MHz
Local oscillator frequency relative to receiver tuned frequency: above.
Receiver tuned frequency is determined as follows:
Fo = Flo
FIF
therefore, Fo,To
Fo,T1
= 1250.764 30
= 1220.764 MHz
= 1250.748 30
= 1220.748 MHz.
The frequency tolerance at time T 1 is calculated as follows:
Frequency tolerance = IFo,
=
o o, 1I T F T
1220.764 1220.748
= 0.016 MHz.
60.5 Receiver radiation.
60.5.1 Objective. The objective of this test is to determine the level of receiver radiated signals at the receiver input terminals.
60.5.2 Requirements. No receiver radiations should exceed the maximum values as specified in table X
for the appropriate radar category.
60.5.3 Application notes. Energy that is generated within the radar receiver by local oscillators and other signal producing circuits may be radiated from the radar system antenna. In this manner, the receiver acts as a transmitter and may emit energy which becomes interference to nearby equipment.
60.5.3.1 To provide assurance that the receiver oscillator radiation meets the requirement, the level of the local oscillator fundamental signal should be determined for all transmitter frequencies which are selected for use in the transmitter tunability test (see 40.7).
60.5.3.2 The test receiver should be a spectrum analyzer or a frequency selective voltmeter (FSVM). The sensitivity of the test receiver should be at least 5 dB greater than the specification limit, measured at the input to the transmission line leading to the test receiver.
60.5.3.3 If numerous oscillator emissions are found in the frequency scan, it may be advantageous to display sequential frequency sectors on the spectrum analyzer, photograph each display and perform the calibration procedure as described for spurious emission (see 40.5). This alternate procedure is especially applicable to frequency scanning or frequency hopping radars where the scan sequence cannot be stopped for single frequency analysis.
60.5.3.4 Over frequency regions where no oscillator radiations are detected, the sensitivity of the test receiver setup should be checked at points over the scan range to demonstrate the required measurement sensitivity. The insertion loss of the adapter used at the receiver input should be determined for each frequency where oscillator radiation is measured.
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