Operating Instructions (18-0015) AM-48 Test Set
0015-S077-34
7.31 Measure S/N Ratio
1. See ¶8.6 for explanation of S/N Ratio measurement.
2. See Figure 7-7. Set switches per the SWITCH SETUP
illustration,
and set the MEASURE cursor per the bottom menu illustration
(SIGNAL-TO-NOISE RATIO DISPLAY).
3. Display indicates frequency of received holding tone, which
must be from 995 Hz to 1025 Hz to be valid. Be sure HOLD
TONE cursor is darkened, indicating a valid holding tone is being
received.
4. A noise-weighting filter is used for this measurement. Set the
FILTER cursor for the desired filter as indicated in Figure 7-7.
5. Read the signal-to-noise ratio on the display. Note that the
reading will always be a whole number.
6. Set Switch 3 to <DAMP> and Switch 14 to <MON RCV> to
audibly monitor the residual noise (see ¶7.5 under
Display
Damping Switch ).
7.32 Measure Phase Jitter
1. See ¶8.10 for explanation of Phase Jitter measurement.
2. See Figure 7-8. Set switches per the SWITCH SETUP
illustration,
and set the MEASURE cursor per the top menu illustration
(PHASE JITTER DISPLAYS).
3. Go to “PLL” display. This indicates the phase-locked loop
generator frequency, which must be from 990 Hz to 1030 Hz for
a valid measurement. Be sure HOLD TONE
cursor is darkened,
indicating a valid holding tone is being received.
4. Go to “RANGE” display. Press [4] or [2] for desired bandwidth
(4 Hz to 300 Hz or 20 Hz to 300 Hz).
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