Rx Dsp Filters; Slope Tune In Action - Kenwood TS-480 User Manual

RX DSP filters

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In SSB, AM and FM modes, you can independently set high- and low-cut frequencies for the AF
filters to suit operating conditions (slope tune).
Fig. 20 illustrates how slope tune works. When there are interfering signals in proximity to the
target signal, you can use a high-cut filter and a low-cut filter to remove the signals above and
below the target.
In SSB mode, installing the optional SSB narrow filter results in even better interference reduction.
In AM mode if you select NAR, RX is possible using this SSB IF filter.
Listed below are the cutoff frequencies (unit: Hz) that can be chosen; default values are shown in
bold.
SSB/FM
Low-cut
0
Hi-cut 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3400 4000 5000
AM
Low-cut
0
Hi-cut 2500 3000 4000 5000
In CW and FSK modes, the AF filters function as a VBT, changing bandwidth without altering the
center frequency. In CW mode, the center frequency is coupled to the CW pitch, whereas in FSK
mode it is determined by the FSK tone and FSK shift frequencies.
Fig. 21 shows how it is possible during CW operations to extract a target signal from surrounding
interference by changing the AF filter bandwidth (WIDTH).
Interference
Low-cut
Interference
Fig. 20: Slope tune in action
100 200 300 400 500 600 700 800 900 1000
50
100 200 500
Target signal
Target signal
Hi-cut
26
Interference
Interference