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13
F
B
ILT ER
A N D W I D T H A N D
Pi t
58
Picture 59
PT-8000 A · B · C User Manual
S
H I F T
Filtering in the PT-8000 is obtained by Roofing Filters (1st IF @ 70.7 MHz)
and Channel Filters (2nd IF @ 10.7 MHZ). The channel filters can be further
enhanced by a DSP (Digital Signal Processing) working in the audio range.
The DSP filtering will:
•
•
•
Acitvating DSP filtering is accomplished by the pushbutton FILTER in the
cluster called DSP. If DSP filtering is engaged, FILTER-LED is on.
After power on the DSP filters are off (Default value).
Appropriate roofing filters are selected automatically
WIDTH and SHIFT control located in the cluster MODE is used to adjust the
filter bandwidth and to shift the passband across the spectrum.
Pushing the knob will toggle between WIDTH and SHIFT function.
In case the FILTER-LED is off only the analogue (Xtal) filters are active. The
selected bandwidth is dispayed and graphically expressed.
The position of the passband relative to the carrier frequency (represented by
a vertical line) is indicated as well.
Pushing FILTER button will activate the DSP. Additional filter will enhance the
overall filter response:
FILTER-LED will be on
The display will indicate DSP operation
Depending on the MODE there are analogue filters available which are
interpolated in bandwidth by the DSP.
F
(W
U N C T I ON
Interpolate between analogue filter bandwidths
Sharpen the filter flanks
Shift the placement of the filters
C–47
/S
)
I D T H
H I F T
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