Hilberling PT-8000A, Руководство по эксплуатации

Страница: 53 / 122

PT-8000A Operating Manual v2.00.33
45
12 F
I L T E R
B
AN D W I D T H AN D
S
H I F T
F
U N C T I O N
FILTER WIDTH / SHIFT
Filtering in the PT-8000A is obtained in the 1st IF @ 40.7 MHz with a 6-pol.
Filter and in the 2nd IF (IF-2) @ 10.7 MHz with an "IM
3
Protector" said prefilter
with bandwidth 0.5 kHz, 3 kHz and 15 kHz.
Prefilters are selected automatically depending on operation mode (default
filter; manual filter selection see Pages 59 and 61)
After passing through the 16-pol. quartz filter ladder the channel selection can
be further enhanced by Digital Signal Processing (DSP) working in the audio
range.
The DSP performs the following tasks:

Interpolation between analogue filter bandwidths @ 10.7 MHz.
 Slope increase of the filter flanks @ 10.7 MHz and elimination of effects
of group delays by the filters.

Shift the placement of the filters (SHIFT function respective band-pass
tuning).
Activating DSP filtering is accomplished by the pushbutton FILTER located in
the cluster DSP (Bandwidth and Shift/Pitch see Page 46 – 12.2).
In case the FILTER LED is off (shown in pic 58) only the analogue (Xtal-) filters
are active. The selected bandwidth is displayed and graphically expressed (see
Page 46 / 12.1).
When pushing FILTER:

The DSP will be activated.

FILTER-LED will be on.
 The display will indicate “DSP” operation.
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, turning will
select the current value.
For specific feature in CW mode see Page 23.
Depending on operation MODE there are analogue filters available which are
interpolated in bandwidth by the DSP (see Page 46).
Fig. 59a
Filter Bandwidth
Transceiver Frequency
DSP activated
Fig. 59b
Fig. 58