Kenwood TS-870S Rejecting Interference, Auto Notch Ssb, Cw/Fsk/Fm, Adaptive Filters

8 REJECTING INTERFERENCE

CHANGING RECEIVE BANDWIDTH						AUTO NOTCH (SSB)
(CW/FSK/FM)						Auto Notch automatically locates and attenuates
The width of the receive pass band can be changed						interfering tones within the receive pass band. This
						function operates digitally at the IF level, hence it can
without altering the current receive frequency. Change
						affect your S-meter reading, and may affect (slightly
the bandwidth by adjusting the LO/WIDTH control.
						attenuate) your desired signal. If interfering tones are
When the control is adjusted, ÒWIDTHÓ and the newly
						weak, you may find that Beat Cancel eliminates them
selected bandwidth appear on the Display.
						more effectively. Also, Auto Notch may not notch out
						signals inside the pass band if signals just outside the
						pass band limits are stronger.
						After switching ON the function, selecting a mode other
		AGC	AUTO		NB
						than SSB will switch OFF the Auto Notch function (LED
					WIDTH
						goes out). Changing back to SSB re-activates the
		CW				function automatically (LED lights). If strong, steady
						interference is present, switching Menu No. 18 (TRACK)
						to OFF may improve the notching capability. To block
						CW interference, switch TRACK to ON, then switch
	CW		FSK		FM	TRACK to OFF to lock the adaptive filter.
	Bandwidth		Bandwidth	Bandwidth		Interfering tone
	(Hz)		(Hz)		(kHz)		Notch band
	50		250	5		Receive pass
						band
	100		500	6
	200		1000	8
	400		1500	10
						Press [AUTO NOTCH] to toggle the Auto Notch function
	600			12
						ON or OFF.
	1000			14		¥ The LED indicator in the button lights when the
		Default values				function is ON.
						Note: The effect of Auto Notch may differ under different receiving
						conditions even when using the same response time.

ADAPTIVE FILTERS

The Auto Notch, Beat Cancel, and Noise Reduction functions accomplish their design purposes by modifying the characteristics of adaptive filters. Adaptive filters adapt or change their characteristics according to the nature of the signal being received at a given moment. Menu No. 18 (TRACK) determines whether the adaptive filters are allowed to change in this manner or not.

It is also possible to specify how long the received signals will be monitored before determining filter characteristics. This monitor period is inversely proportional to the response time. The longer the monitor time, the slower the response time and vice versa. Use Menu No. 14 (LINE.ENH) to select a different Line Enhance response time, Menu No. 16 (SP.BEAT) for the Beat Cancel response time, and Menu No. 17 (SP.NOTCH) for the Auto Notch response time.

The adaptive filters may not function correctly with signals that have a poor signal-to-noise (S/N) ratio. Under poor conditions, you may find that optimum results are obtained by switching OFF the adaptive filters via Menu No. 18 (TRACK).

Note: Only Auto Notch, or Beat Cancel, or Noise Reduction can be used at one time. They cannot be activated at the same time. Also, Menu No. 18 changes to its default setting when the TS-870S power is switched OFF and then ON again.

BEAT CANCEL (SSB/AM)

Beat Cancel also attenuates unwanted tones within the pass band, but it is more capable than Auto Notch at removing low-level tones. Also, this function works at the AF level, therefore you will notice there is no S-meter signal loss, although the S/N ratio may be lowered in the AM mode.

After switching ON the function, selecting a mode other than SSB or AM will switch OFF the Beat Cancel function (LED goes out). Changing back to SSB or AM re-activates the function automatically (LED lights).

Interfering tones

Receive pass band Receive pass band

Press [BEAT CANCEL] to toggle the Beat Cancel function ON or OFF.

¥The LED indicator in the button lights when the function is ON.

Note: The effect of Beat Cancel may differ under different receiving conditions even when using the same response time.

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