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The top right soft key selects the notch steering mode. There are three
notch steering modes, selected by subsequent presses:
.
OFF – In this mode, the filter is tuned to either 400 Hz or 1 kHz,
as displayed in the bottom left corner of the display.
.
GEN-TRACK – This causes the notch to be tuned to the
generator frequency.
.
FIX-TUNE – This causes the notch to be tuned to a frequency
specified by the user. The current tuning frequency will by
shown on the upper right ofthe display, and it may be adjusted
with the FREQUENCY controls. This will not give a valid
SINAD reading unless it is tuned to the fundamental frequency
on the input.
SINAD measurements are generally taken at 400 Hz or 1 kHz, so these
frequencies are designed to be the most convenient. When the notch
steering mode is set to ‘OFF’, the lower left soft key selects between
400 Hz and 1 kHz. Changing this setting changes both the generator
and the notch filter to the selected frequency. The generator frequency
may then be changed using the FREQUENCY controls, but the notch
will remain parked, so the reading will be invalid.
The SINAD mode also provides bandwidth limiting. The lower center
soft key selects the lower band limit (<10 Hz, 22 Hz or 400 Hz). The
lower right soft key selects the upper band limit (>300 kHz, 22 kHz, 22
kHz-QPK, 30 kHz, 80 kHz). The 22 kHz-QPK selection uses the
quasi-peak detector instead ofthe true RMS detector in accordance
with CCIR-468. The 22 Hz lower limit is only available ifthe upper
limit is 22 kHz; the <10 Hz lower limit is only available with other
upper limits.
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Oper
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Controlling the Analyzer : SINAD
Operation
Portable One Plus Access User's Manual
4-39
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