MIL-STD-469B APPENDIX A
where:
BNOM = spectrum analyzer IF bandwidth (3 dB), in Hz
Ts = sweep time, seconds
Fs = sweep width, in Hz .
Other controls should be set in accordance with the analyzer operating manual, the control settings recorded, and then the display should be photographed.
40.4.4.5 The analyzer display should be calibrated as follows: Connect a calibrated CW signal generator to the spectrum analyzer, then tune it to the center of the analyzer display. Adjust the generator level to produce a display at the top horizontal graticule line. Record the signal generator frequency and output level. Adjust and record the generator level for each horizontal line. Tune the signal generator frequency so that the display is coincident with the right-hand end of the analyzer display. Increase or decrease the signal generator output as required to attain a display at the middle horizontal graticule line. Note the generator output level and frequency at this point, then tune the generator to the left-hand end of the display and repeat the process.
If the levels at the analyzer display end points differ by greater than 2 dB from the mid-frequency level, select additional points across the display frequency range as necessary to describe the overall linearity characteristics.
40.4.4.6 The test setup should be reconnected to the radar signal sample point. The analyzer sweep width should be increased for an optimum display of the radar emission at the 40 dB points below the maximum level at Fo. The analyzer sweep rate should be changed as necessary to satisfy the (B NOM)2(Ts/Fs)>5 requirement. The display should be photographed and the calibration procedure performed as described for
the first photograph.
40.4.4.7 The next part of the procedure requires a tunable preselector which tracks with the sweep frequency of the spectrum analyzer inserted at the analyzer input. After reconnecting the test setup to the radar signal sample point, the spectrum analyzer should be tuned above the radar F o until the 40 dB down amplitude point appears near the low frequency end of the display. Remove part of the calibrated input
attenuation to raise the entire spectrum display higher on the analyzer screen. In removing the attenuation, the level applied to the preselector and analyzer should be maintained below the value which produces overload
or signal compression in the display. The amplitude of the overall spectrum envelope, at the minus 40 dB amplitude and lower, should be raised on the display by an amount equal to the attenuation removed. The level at the minus 40 dB amplitude point should remain on scale. The analyzer sweep width which will show the upper end-point of the spectrum rolloff region should be selected. The analyzer sweep rate should be adjusted to satisfy the criteria given for the first two photographs. The display should be photographed and calibrated using the procedure given for the first photograph. The procedure described should be repeated with the spectrum analyzer tuned below the radar F o.
40.4.4.8 The procedure for CW and FM/CW radars is similar to that for pulsed radars described above except that it is not necessary to determine the alpha factor and the criteria for selecting the analyzer bandwidth is as follows:
F re F the
a. For a CW radar, select the analyzer IF bandwidth (B) such that B <(3x10
radar tuned frequency, in Hz.
5) , whe is
b. For FM/CW radars, select the analyzer IF bandwidth (B) such that B <(3x10
FMOD, whichever is less. FMOD is the modulation rate for the FM.
5)F or B < 0.5
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