Rejecting Interference, DSP Tools, 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
Adjust	Mode	Frequency Selections	Freq.
			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)	AM	0, 100, 200, 500 Hz	100 Hz

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
(low-pass	AM	2.5, 3.0, 4.0, 5.0, 6.0, 7.0 kHz	6.0 kHz
filter cutoff)	AM	2.5, 3.0, 4.0, 5.0, 6.0, 7.0 kHz	6.0 kHz

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

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

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

TS-870S specifications

The Kenwood TS-870S is a distinguished transceiver that stands out in the world of amateur radio, particularly for enthusiasts who seek a blend of advanced technology and user-friendly features. Introduced in the early 1990s, this HF transceiver quickly gained a reputation for its exceptional performance, versatility, and reliability, making it a favorite among operators worldwide.

One of the most noteworthy features of the TS-870S is its direct-sampling technology, which allows for superior signal fidelity and processing. This technology enables the transceiver to operate across a range of 160 meters to 10 meters, catering to both casual and serious operators. Its high-performance 16-bit digital signal processing (DSP) facilitates effective noise reduction and filtering capabilities, enhancing the overall clarity during transmission and reception.

In terms of power, the TS-870S boasts an output of 100 watts, providing ample power for various communication needs. The transceiver is equipped with an automatic antenna tuner, which simplifies the task of matching the antenna to the operating frequency, ensuring optimal performance without the hassle of manual adjustments.

Another significant aspect of the Kenwood TS-870S is its user interface, featuring a large, easy-to-read display, and a logically arranged control layout. This makes it accessible for both novice and experienced operators. The built-in memories allow for quick storage and access to favorite frequencies and settings, enhancing operational efficiency.

The Kenwood TS-870S also includes various advanced features such as an optional 2.4 kHz and 6 kHz roofing filter which provides improved performance in crowded band conditions. The receiver's dual VFOs (Variable Frequency Oscillators) enable simultaneous monitoring of two frequencies, which is particularly useful for operators who need to keep track of multiple signals or engage in cross-band communication.

Apart from its technical specifications, the TS-870S is constructed with durability in mind, ensuring that it can withstand the rigors of frequent use. It supports various operating modes, including SSB, CW, AM, and FM, making it a versatile choice for diverse amateur radio activities.

In conclusion, the Kenwood TS-870S combines advanced technology with user-friendly characteristics, offering amateur radio operators an exceptional tool for communication. With its innovative features, robust performance, and flexibility, it continues to be a respected choice among radio enthusiasts, solidifying its legacy in the realm of amateur radio.