Kenwood TS-870S Rejecting Interference, Dsp Tools, Slope Tuning Ssb/Am, If Shift Cw

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.

LO/WIDTH	USB pass band
	f
LO/WIDTH	USB pass band
	f

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.

HI/SHIFT	USB pass band
	f
HI/SHIFT	USB pass band
	f

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	Default
			Freq.
LO/WIDTH	SSB	0, 50, 100, 200, 300, 400,	300 Hz
Control		500, 600, 800, 1000 Hz
(high-pass	AM	0, 100, 200, 500 Hz	100 Hz
filter cutoff)
HI/SHIFT	SSB	1.4, 1.6, 1.8, 2.0, 2.2, 2.4,	2.6 kHz
Control		2.6, 2.8, 3.0, 3.4, 4.6, 6.0 kHz
(low-pass
	AM	2.5, 3.0, 4.0, 5.0, 6.0, 7.0 kHz	6.0 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, ÒSHIFTÓ and the newly selected center frequency appears on the Display.

AGC AUTO	CTRL
	SHIFT

CW

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: 800 Hz (center frequency)

¥CW Width: 600 Hz

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 CW pitch was set for 900 Hz, the signal would be audible.

After adjusting IF Shift:

¥CW pitch: 900 Hz

¥ IF Shift: 500 Hz (center frequency)

¥CW Width: 600 Hz

900 Hz pitch 900 Hz pitch

500 800 1100 200 500 800

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 100 Hz.

Mode	Freq./ Filter	Frequency Selections	Default
	Relationship	(Hz)	Freq.(Hz)
CW	Center	400, 450, 500, 550,	800
	frequency	600, 650, 700, 750,
		800, 850, 900, 950,
		1000

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