Chapter 8 Rejecting Interference; Dsp Tools; Slope Tuning (Ssb/Am); If Shift (Cw) - Kenwood TS-870S Instruction Manual

REJECTING INTERFERENCE

DSP TOOLS

SLOPE TUNING (SSB/AM)

Changing the positions of the LO/WIDTH and HI/SHIFT
controls while in SSB or AM mode changes the cut-off
frequencies for the receive pass band. Controlling the
pass band in this way allows you to eliminate adjacent
frequency interference.
Turn the LO/WIDTH control clockwise to raise the
high-pass filter cut-off frequency; turn it
counterclockwise to lower the cut-off frequency. This is
effective in removing interference from frequencies
lower than your current operating frequency.
USB pass band
LO/WIDTH
USB pass band
LO/WIDTH
Turn the HI/SHIFT control clockwise to raise the
low-pass filter cut-off frequency; turn it
counterclockwise to lower the cut-off frequency. This is
effective in removing interference from frequencies
higher than your current operating frequency.
USB pass band
HI/SHIFT
USB pass band
HI/SHIFT
Using only these controls, you can eliminate a great
deal of interference on the phone bands. By using both
controls together carefully, you will increase your ability
to pick out weak signals from the interference.
Adjust Mode Frequency Selections
LO/WIDTH
0, 50, 100, 200, 300, 400,
SSB
Control
500, 600, 800, 1000 Hz
(high-pass
AM
0, 100, 200, 500 Hz
filter cutoff)
HI/SHIFT 1.4, 1.6, 1.8, 2.0, 2.2, 2.4,
SSB
2.6, 2.8, 3.0, 3.4, 4.6, 6.0 kHz
Control
(low-pass
AM
2.5, 3.0, 4.0, 5.0, 6.0, 7.0 kHz
filter cutoff)

IF SHIFT (CW)

For CW, the center frequency of the filter pass band can
be shifted without changing the current receive
frequency. This is an additional method of fighting
adjacent frequency interference. Change the CW
center frequency by adjusting the HI/SHIFT control.
When the control is adjusted, "SHIFT" and the newly
selected center frequency appears on the Display.
Be aware that shifting the CW center frequency does
not automatically adjust the receive CW pitch.
Therefore, it is possible to shift the CW pass band such
that the selected CW pitch frequency falls outside the
pass band. Doing this makes the CW signal inaudible.
Example:
Before adjusting IF Shift:
• CW pitch: 900 Hz
• IF Shift:
• CW Width: 600 Hz
f
In this example, the pass band would lie from
500 ~ 1100 Hz (from 300 Hz below the center frequency
of 800 Hz to 300 Hz above the center frequency). If the
f
CW pitch was set for 900 Hz, the signal would be
audible.
After adjusting IF Shift:
• CW pitch: 900 Hz
• IF Shift:
• CW Width: 600 Hz
f
f
500
Now, the pass band would lie from 200 ~ 800 Hz. With
the CW pitch set for 900 Hz, the signal would not be
audible since the pitch frequency is 100 Hz above the
upper edge of the pass band. In this case, to make the
signal audible, lower the CW pitch frequency by at least
Default
100 Hz.
Freq.
Freq./ Filter
300 Hz
Mode
Relationship
100 Hz
CW
frequency
2.6 kHz
6.0 kHz
AGC AUTO
CW
800 Hz (center frequency)
500 Hz (center frequency)
900 Hz pitch
800 1100 200 500
Frequency Selections
(Hz)
400, 450, 500, 550,
Center
600, 650, 700, 750,
800, 850, 900, 950,
1000
CTRL
SHIFT
900 Hz pitch
800
Default
Freq.(Hz)
800
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