Operating instructions

LOCAL OPERATION
3-62 46882-311D
The monitor software calculates the SINAD level according to the formula:-
SINAD
= 20
1
2
log
V
V
dB
=
++
+
20 log
()
()
SND
ND
dB
The distortion bar chart ranges available are 0 to 18 dB and 0 to 50 dB. The SINAD level is
displayed as a digital readout above the bar chart. The AF test menu is recalled automatically
after pressing this key.
Dist’n
Selects distortion percentage as the measurement method. The AF generator is set to 1 kHz and
the 1 kHz distortion notch filter is switched alternatively in and out of circuit, with the signal
level being measured by the AF voltmeter in each state. See Fig. 3-8 a, b, & c, Distortion level
and signal to noise level measurements, on page 3-33.
The monitor software calculates the distortion level according to the formula:-
Distortion
= 100
2
1
V
V
%
=
+
++
100
()
()
%
ND
SND
The distortion bar chart ranges available are 0 to 10% and 0 to 30%. The distortion percentage
level is displayed as a digital readout above the bar chart. The AF test menu is recalled
automatically after pressing this key.
*Oscilloscope*
The oscilloscope facility can be used from within the AF test mode to examine the signal present
at the AF input socket. The sensitivity of the Y axis is adjustable from 10 mV/division to
20 V/division in a 1,2,5 sequence.
The input to the oscilloscope is taken directly from the AF input, and not through any of the AF
filters. Therefore measurements obtained on the AF voltmeter will show the effects of filtering,
whereas those made using the oscilloscope will not.
A section on the use of the oscilloscope facility starts on page 3-80.
Incremental adjustment keys
General
This section provides information on the use of the incremental adjustment keys. Other sections
of this chapter have specific references to these keys; this section gives general information.
The incremental adjustment keys are located under the variable control, with one pair designated
FREQ, [
] and [ ], the other pair designated LEVEL, [ ] and [ ]. Each pair can be assigned
to a selected parameter within a test mode, which then allows that parameter to be adjusted in
steps.
Note that the FREQ [
] and [ ] keys, and the LEVEL [ ] and [ ] keys, do not have to be
assigned to the same generator.
The parameters that can be selected are:-