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47
10 REJECTING INTERFERENCE
BEAT CANCEL (SSB/ FM/ AM)
Two types of Beat Cancel DSP filters are available.
Beat Cancel 1 (BC1) is effective for removing a weak
beat or continuous beat signals. Beat Cancel 2
(BC2) is effective for removing intermittent beat
signals, such as CW signals.
Before
Interfering
tone
After
Filter pass band (AF)
Desired
signal
Press [BC/ CW.T] to cycle through Beat Cancel 1,
Beat Cancel 2, and OFF.
• “1
t
BC” or “BC
s
2” appears when the Beat Cancel
function is ON.
• The interfering beat signals are removed.
NOISE REDUCTION (ALL MODES)
This transceiver provides 2 types of Noise Reduction
functions (NR1 and NR2) for reducing random noise
which interferes with the desired signal. Trying them
both is the easiest way to judge which function works
more effectively under the current conditions.
Normally, select NR1 (Line Enhanced) in SSB mode
and NR2 (SPAC) in CW mode.
Press [NR] to toggle between NR1, NR2, and OFF.
•“1
tt
tt
t
NR” or “NR
ss
ss
s
2” appears, depending on which
type of noise reduction filter is selected.
■ Setting the NR1 Level Adjustment
The NR1 (Line Enhanced Method) uses an
adaptive filter to reduce the noise element from
the received signals. When the S/N ratio is
reasonably good in SSB, using the NR1 will
improve the S/N further.
While NR1 is ON, you can further adjust the noise
reduction level by pressing [NR] (1 s), then turn the
MULTI control to select the level from 1 to 9 or
AUTO. The default is AUTO.
■ Setting the NR2 Time Constant
You can change the correlation time for NR2
(SPAC). When in SSB mode, select the
correlation time that allows you to hear signals
with clarity. When receiving CW, it is best to
select the longest correlation time that allows
reliable reception. The longer the correlation time,
the better the S/N ratio.
When NR2 is ON, press [NR] (1 s), then turn the
MULTI control to select the correlation time from
2 ms to 20 ms. The default is 20 ms.
Note:
Using Noise Reduction 2 in SSB mode may lower the
clarity of signals or induce pulse noise, depending on the
conditions.
NOISE BLANKER
Noise Blanker was designed to reduce pulse noise
such as that generated by automobile ignitions.
Noise Blanker does not function in FM mode.
Press [NB/T/ 7] to toggle the Noise Blanker ON and
OFF.
• “NB” appears when the function is ON.
You can further adjust the Noise Blanker level from
1 to 10. The default level is 6.
Press [NB/T/ 7] (1 s), then turn the MULTI control to
adjust the Noise Blanker level.
• “NB LV.” and the current level appear on the sub-
display.
Note:
◆
Noise Blanker is available only for SSB, CW, FSK, and AM
modes.
◆
Increasing the Noise Blanker level degrades the intermodulation
characteristics of the transceiver.
DIGITAL NOISE LIMITER (DNL)
Digital Noise Limiter (DNL) is designed to reduce
pulse noise such as that generated by automobile
ignitions. Try this function when the Noise Blanker
function cannot remove the pulse noises effectively.
Digital Noise Limiter does not function in FM mode.
Press [DNL] to toggle the DNL ON and OFF.
• “DNL” appears when the function is ON.
You can further adjust the DNL level from 1 to 3.
The default level is 2.
Press [DNL] (1 s), then turn the MULTI control to
adjust the Digital Noise Limiter level.
• The current level appear on the sub-display.
Note:
◆
Digital Noise Limiter is available only for SSB, CW, FSK, and AM
modes.
◆
Depending on a pulse type, the DNL function may not be able to
remove the noise.
◆
Turning the DNL function ON when there is no pulse-type noise
and the signal is relatively strong, it could degrade the signal
readabilty.
◆
When the DNL function is ON, the high-cut filter frequency
becomes 3.0 kHz regardless of the DSP filter settings.
◆
The DNL function can be used with the Beat Cancel (BC), Noise
Reduction (NR) , and Noise Blanker functions at the same time.