Kenwood TS-890S In-Depth Manual page 37

Table 6
RX Mode
SSB (Low-cut, High-cut)
SSB (WIDTH), FSK, PSK
CW
Fig. 37 Comparison of IF Filter Shapes in the SSB Mode (Sharp, Medium, Soft)
Fig. 38 Comparison of IF Filter Shapes in the CW Mode (Sharp, Medium, Soft)
The shape factors for determining the IF filter shape are designed based on a 2400 Hz passband width in the SSB, FSK
and PSK modes and a 500 Hz passband width in the CW mode. By changing the high-/low-cut or WIDTH settings, it is
possible to alter the passband width while maintaining the slope characteristics from cut-off up to the attenuation range.
Compared to the filter shape in the SSB mode, the reference passband width that determines the shape factor is
narrower in the CW mode, which means the filter is sharpest in the CW mode. Such a sharp filter tends to cause ringing
when the bandwidth is narrowed, and may affect the sound quality due to group delay in the SSB mode.
Employing the digital filter design technology that we have accumulated, the TS-890S now offers a filter and IF-AGC
design that minimizes ringing as well as impact on the sound quality. As the roofing filter settings for the analog circuit
vary in tandem with the specified filter bandwidth characteristics, interference by adjacent signals is less likely to occur
when a narrow band of 500 Hz or lower is configured in the CW mode. At the same time, however, the ripple and group
delay characteristics may also be affected in some cases.
Because of the relationship with the analog filter characteristics, only devising the digital filter does not attain practical
listening sensation in sound quality refining. Tuning of IF-AGC described above helps to bring out the filter characteristics
effectively.
IF Filter Characteristics (Slope Characteristics) and Shape Factors
（-60 dB BW/-3 dB BW）
1.6/ 1.8/ 2.0 (Low-cut filter: 200
Hz, High-cut filter: 2600 Hz)
1.5/ 1.8/ 2.0 (Bandwidth: 2400 Hz)
1.5/ 1.8/ 2.0 (Bandwidth: 500 Hz)
Shape Factor
Frequency (Hz)
Frequency (Hz)
DSP 07
Stop Band
Attenuation
110 dB
110 dB
110 dB
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