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 either the
analog or digital generator frequency. If the Generator Control
mode is Analog Audio Generator, then the notch will track the
analog generator. If it is one of the digital modes, the notch will
track the embedded audio signal on the digital generator.
.
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 of the 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.
In either GEN-TRACK or FIX-TUNE mode, the upper right section of
the display will show the current center frequency of the notch filter.
In OFF mode, the current notch frequency is shown above the lower
left soft key.
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 of the true RMS detector in accordance
with CCIR-468. The 22 Hz lower limit is only available if the upper
limit is 22 kHz; the <10 Hz lower limit is only available with other
upper limits.
4 Functions
SINAD Function Descriptions
4-22 ATS-1 Dual Domain User's Manual
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