WiNRADiO G65DDC User’s Guide
95
the Test frequency equal to the modulating frequency (typically 1 kHz). Adjust
the IF bandwidth for the maximum SINAD. Then gradually keep reducing the
generator output level to the point when SINAD drops to 10 dB. The receiver
sensitivity is then equal to the generator level at this point.
Measuring AM sensitivity using SINAD rather than the conventionally used
S+N/N is quite appropriate as SINAD also includes distortion, which is as
much an impediment to intelligible reception as noise, and therefore provides a
more practical result. Even though in theory using SINAD should result in the
sensitivity figures being somewhat worse than if S+N/N is used, in practice,
with a good receiver such as the Excalibur Sigma, there is no noticeable
difference.
Note: When measuring sensitivity using SINAD, it is very important that
the Audio Filter is enabled and the cut-off frequencies (and for FM
measurements, also the de-emphasis) are set according to the specified
test conditions. Proper audio filtering makes a substantial difference to
the SINAD results.
Show Waterfall Timestamps
Invoking this option makes the DDC1 waterfall spectrum display show time
stamps, making it possible to relate spectrum events to absolute time:
Show Last Clicked Marker
If this option is selected, all the spectrum displays (including sweeper and
activity displays) will show a marker at the position of the "
last clicked on
frequency
" to which the receiver was tuned. Passband-dragging zones are
excluded as possible last-click marker positions.
