If Filter - Kenwood TS-890S In-Depth Manual

07 DSP

IF Filter

As the main band limitation filter, the TS-890S is equipped with roofing filters for the analog stage as well as DSP digital
IF and AF filters (in addition to these, there are also audio peak filters, etc.).
In the SSB, CW, FSK, PSK modes, IF filter is installed in the preceding stage to the in-band AGC and AF filter to the
succeeding stage. In the AM mode, the IF filter is also installed in the preceding stage to the in-band AGC but the AF
filter is positioned after demodulation. In the FM mode, the IF filter is installed in the stage preceding demodulation, and
the AF filter in the stage after demodulation.
Operating the transceiver to change the low-/high-cut filter or WIDTH alters the cut-off frequency of the roofing filters, IF
filter and AF filter at the same time. However, the settings can also be changed to alter the frequency individually.
In the SSB mode, the IF filter is made up of a high-pass filter (high-cut) and a low-pass filter (low-cut), which allows the
high-cut and low-cut frequencies to be altered. In the CW, FSP and PSK modes, the IF filter is made up of a bandpass
filter, which allows WIDTH (passband width) and SHIFT (center frequency of filter) to be altered. In the SSB mode, the
settings can be configured to change the low-/high-cut combination to WIDTH/SHIFT combination.
Compared to conventional models, the TS-890S offers a significantly wider variety of filter options in all the modes for
more detailed tuning. In the AM mode, the passband width of the IF bandpass filter varies according to the high-cut
setting of the AF filter. In the FM mode, the passband width of the IF filter varies when the setting is switched between
Wide and Narrow.
Frequency (Hz)
Fig. 35 IF Filter Characteristics in the SSB Mode (IF Filter Shape: "Medium")
Frequency (Hz)
Fig. 36 IF Filter Characteristics in the CW Mode (IF Filter Shape: "Medium")
In addition to the high-cut, low-cut and WIDTH settings, it is also possible to switch the IF filter shape (slope
characteristics) on the TS-890S. To switch the IF filter shape, select "Sharp", "Medium" or "Soft" on the RX Filter screen.
The "Sharp" filter has the steepest slope, while the "Soft" filter has the most gentle slope
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