Model 8640B
TM 9-4935-601-14-7&P
PERFORMANCE TESTS
4-19. SINGLE SIDEBAND PHASE NOISE TEST (Cont'd)
NOTE (Cont'd)
b.
+2.5 dB because noise is average detected after logging*.
c.
-0.8 dB. Effective noise BW is 1.2 x 3 dB BW which gives -0.8 dB - 10 log (actual 3 dB
BW/nominal 3 dB BW)*.
Summing the correction factors gives -4.3 dB 10 log (actual 3 dB BW/nominal 3 dB BW) or
approximately -4.3 dB ±1 dB.
5.
Phase lock the generators by setting test generator's FM switch to DC and by tuning reference signal generator to
550 MHz (i.e., for a difference frequency of 0 Hz). Monitor phase lock on oscilloscope, checking that mixer's
output is 0 Vdc (if it is not, fine tune reference generator until it is).
6.
Set analyzer's display smoothing (video filter) to 10 Hz. Set step attenuator to 0 dB. The top (reference) graticule
line on analyzer's display represents 110 dB/Hz below carrier level (the transfer from a 1 kHz BW to a 1 Hz BW is
30 dB). The average noise level on the display should be> 12 dB below top graticule line at 20 kHz (i.e., > 122 dB
below carrier).
12 dB ___________________________
NOTE
Set oscilloscope to check for possible line-related signals in test setup. They should be < 10
mVp-p.
7.
Set test Signal Generator to 450 MHz and FM switch to OFF. Set reference signal generator to 449.98 MHz (i.e.,
20 kHz below the test generator's frequency). Repeat steps 2 through 6. The average noise level on the display
should be > 20 dB below top graticule line at 20 kHz.
20 dB ___________________________
NOTE
SSB phase noise can be checked at any other frequency from 230 kHz to 550 MHz by following
the procedures given above. Noise decreases approximately 6 dB per each octave band change
down to -140 dB below carrier.
4-20. SINGLE SIDEBAND BROADBAND NOISE FLOOR TEST
SPECIFICATION:
SSB Broadband Noise Floor at maximum output vernier and greater than 500 kHz offset from carrier: (Averaged rms
noise level below carrier stated in a 1 Hz bandwidth.) 0.5 to 512 MHz: >140 dB.
* See Hewlett-Packard Application Note 150-4. Spectrum Analysis - Noise Measurements.
4-17
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