MIL-STD-469B APPENDIX A
40.2.3.2 For radar systems having multiple modulation modes or frequency bands, the power output measurements should be performed for each mode and band combination. The transmitter frequency stability (see 40.6) and tunability (see 40.7) should be performed at the same time as the power output tests.
40.2.3.3 For phased array systems with less than fifteen transmitters/tubes the power output of each transmitter/tube should be measured. For phased array systems with fifteen or more transmitters/tubes, the power should be either measured in the far-field or statistically determined by measuring the power outputs of a selected number of transmitters/tubes. The transmitters/tubes to be tested should be determined using a table of random numbers for selection. Initially fifteen of the transmitters/tubes should be selected for measurements purposes. The standard deviation of the measured data, corrected for any antenna amplitude weighting factor, should be calculated. If the standard deviation is greater than 2.0 dB, additional transmitters/tubes should be measured. The number of transmitters/tubes to be measured should 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 should then be the mean power output in watts, corrected for antenna weighting, times the total number of transmitters.
40.2.3.4 If the pulse shape of the transmitter output pulse is essentially rectangular, i.e., t r and tf are less than t/10, and the pulse width and PRF values are known or measured, the radar peak output should be determined by measuring the average power output and converting the measured value to peak power output using the radar duty cycle factor.
40.2.3.5 If the radar modulation is complex, for example, the pulse width or PRF parameters are not easily determined, the radar peak power output should be measured.
40.2.3.6 The test receiver for direct measurement of the radar peak power output should be a frequency selective voltmeter (FSVM) or broadband crystal detector, depending upon the bandwidth required for reproducing the radar pulse envelope. The criteria for determining the bandwidth required is BW = 2/t.
40.2.4 Procedure. The test setup block diagram for tranmitter power output measurement is shown on figure 1. The procedures for this test should be as specified in 40.2.4.1 through 40.2.4.4.
40.2.4.1 The radar should be tuned to one of the specified operating frequencies and adjusted for its normal operating conditions. Attenuators, if necessary, should be connected to the signal sampler as shown on figure 1.
40.2.4.2 For average power measurements, the power meter reading (P M) should be noted. Pulse width (t)
and PRF measured values should be obtained as described in 40.3.
40.2.4.3 For peak power measurements with the FSVM as the test receiver, attenuation should be inserted at the signal sampler to yield a peak level of minus 10 dBm or less at the FSVM input. After tuning the FSVM for maximum response, the meter reading should be noted for reference. Tune the test signal generator to the FSVM frequency. With the test signal generator set for CW output, reference the output level (set for minus 10 dBm or less) to a selected value on the power meter. Set the test signal generator to pulsed output. The width of the output pulse should be adjusted to the value obtained from the following equation:
PWTEST = t; non-pulse compression radar or
PWTEST = XPW; pulse compression radar
25
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business