MIL-STD-469 Radar Engineering Interface Requirements, Electromagnetic Compatibility See Notice 1 For Replacement InformationThis standard establishes the engineering interface requirements to control the electromagnetic emission and susceptibility characteristics of all new military radar equipment and systems operating between 100 megahertz MHz, and 100 gigahertz GHz, to ensure EMC in all intended operational environments, and to conserve the frequency spectrum available to military radar systems.

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MIL-STD-469B APPENDIX A

40.6.5  Sample calculations.  The results from the frequency stability measurements consist of the transmitter frequency and times of measurement plus test particulars such as mode of transmitter operation, ambient temperature, and time from cold start to first frequency measurement. It is possible that a given system may be intended to be kept at a condition other than cold as its normal off mode. An explanation should be provided when the system under test is not operated from a cold start. Sample data sheets to be used for reporting test details and measurement results are shown on figures 21 and 22.

40.6.5.1  A sample calculation to determine the frequency stability at one measurement follows: Frequency at transmitter cold start (T o) = 2100.031 Mhz

Frequency after 5 minutes of operation (T o  + 5) = 2100.014 MHz

Frequency tolerance     = 1F(To)

o  + F(T      5)1

= 12100.031     2100.0141

= 0.017 MHz.

40.7  Transmitter tunability.

40.7.1  Objective.  The objective of this test is to determine the ability of the radar transmitter to tune over its approved frequency band.

40.7.2  Requirements.  Each radar should be tunable in an essentially continuous manner (see 5.3.4).

40.7.3  Application notes.  The procedure for the transmitter tunability test consists of performing the transmitter power output and output frequency test with the transmitter tuned, in turn, to each of the required test frequencies. The test procedures for measuring the transmitter power output and  operating frequency are described (see 40.2 and 40.6). Refer to 40.2 and 40.6 for the individual test procedures; the selection of the required test frequencies is described in 40.7.4. In the initial selection for each radar band, at least 11 test frequencies should be used, as specified herein: F L, FM, FH; four frequencies approximately evenly spaced between FL  and FM, and four frequencies approximately evenly spaced between F M  and FH. In the absence of specific requirements for power output in the radar procurement specification, test criteria for radar system tunability should be derived from system specifications that define operational performance requirements.

40.7.4  Procedure.  At each tuned frequency, the transmitter should be adjusted for normal operation as described by the system operating manual. Any efforts to optimize the equipment operation at a particular frequency should not be attempted unless the procedure is described in the manual.

40.7.4.1  The measured power output values should be compared to the radar specifications. If measured values differ by more than 2 dB from the specification values, additional frequencies should be tested near the frequency where the discrepancy is noted in order to describe the problem. For systems which are fixed-tuned or have less than 11 operating frequencies, the number of test  frequencies should be reduced to the maximum available.

40.7.5  Sample calculations.  The sample calculations for obtaining the transmitter power output from measured data are described (see 40.2). Sample data forms for recording the power output results are shown (see figures 2 and 3).

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