MIL-DTL-52872D
APPENDIX A
TEST METHOD 2
PERFORMANCE TEST
1.
TEST APPARATUS:
a.
Power supply, dc - constant voltage, continuously variable, 0 to
24 Vdc, 120 mA minimum current capacity, line and load
regulation 0.1 percent or less, maximum ripple 5 mV P-P.
b.
Power supply, dc - constant voltage, continuously variable, 0 to
30 Vdc, 200 mA minimum current capacity, line and load
regulation 0.5 percent or less, maximum ripple 20 mV P-P.
c.
Voltmeter, dc - 3 1/2 digit or greater, resolution 10 mVdc
(range 19.99 V), minimum accuracy 0.5 percent of reading ±2 LSD.
d.
Resistor - 2.7k ohms ±5 percent, 1/2 watt.
e.
Wideband ultrasonic signal generator (WUSG) - Signal generator
producing ultrasonic broadband noise of variable amplitude,
hard-wire or radiated (see 6.4.5 for definition; see figure 1
for an alternative schematic).
f.
Sound level meter with microphone - measuring range 35 dB to 140
dB minimum SPL with respect to RSPL (.0002 microbars), frequency
weighting A, linear and all pass, frequency response 20 Hz to 50
kHz.
g.
Oscilloscope - 20 MHz bandwidth, vertical sensitivity 5mV per
div. to 5 V per div., sweep rate < 1 microsecond per div. to > 1
second per div., internal/external trigger, ac and dc coupled
inputs.
h.
Doppler signal synthesizer - as required to perform test
procedure (see also 6.4.4).
2.
TEST PROCEDURE:
2.1.
Alarm criteria for noise.
a.
Place 19 of 20 transceivers in an acoustically quiet,
motion-free area. One test transceiver shall be excited by the
synthesizer test signals.
b.
Connect all 20 transceivers to TB2 of the processor by 500 feet
of cable. Place the sound level meter microphone in close
proximity to the test transceiver receive transducer.
c.
Set all transceiver range controls to position 10.
d.
Place the UMS in operation by applying 20 ±0.3 Vdc to processor
terminals TB1-7 and TB1-8.
e.
Operate the WUSG to radiate broadband ultrasonic noise to the
microphone and test transceiver. With the sound level meter
passband adjusted for the frequency octave centered at 31.5 kHz,
adjust the WUSG output level to read 65 dB above RSPL (0.0002
microbar) on the sound level meter.
f.
Turn off the ultrasonic noise and momentarily short circuit
capacitor C54 (56 microfarads) to reset the noise detector.
g.
Turn on the ultrasonic noise for 5 seconds. The UMS shall
alarm.
2.2.
Alarm criteria for unidirectional motion.
2.2.1
Target signals and background clutter.
a.
With the processor and transceiver interconnected as in 2.1b,
air-couple the transceiver transmit transducer to the Doppler
signal synthesizer input.
b.
Hard-wire the WSUG output to be summed with the Doppler signal
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