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12 REJECTING INTERFERENCE
NOTCH FILTER (SSB)
Auto Notch filter automatically locates and attenuates
any single interfering tone within the receive pass
band. This function operates digitally at the IF filter
level, hence it can affect your S-meter reading and
may also affect (slightly attenuate) your desired
signal. However, controlling the AGC level by
notching out the strong interfering beat signals could
bring up the desired SSB signal that is covered by the
interfering beat signal. If the interfering tone is weak,
you may find that Beat Cancel eliminates them more
effectively.
Before
Interfering
tones
After
Receive pass band
Desired
signal
Press [A.N./ LEVEL] to toggle the Auto Notch Filter
ON and OFF.
• “A.N.” appears when the function is ON.
• The interfering beat signals are notched out.
If the interfering beat signals change the tone
frequency randomly, you can adjust the Auto Notch
level.
Press [FUNC], [A.N./ LEVEL] to access the Auto
Notch level adjustment, then turn the MULTI/ CH
control to select the level from FIX, and 1 to 4.
Level 1 is the slowest beat tone tracking speed and
Level 4 is the fastest. FIX terminates the beat tone
tracking. Adjust this pamameter manually to remove
the beat signal if necessary.
AUTO BEAT CANCEL (SSB/ AM)
Auto Beat Cancel uses an adaptive filter and
attenuates more than one cyclic interference within the
receive pass band. The adaptive filter changes its
characteristics according to the nature of the signal
being received at any given moment. You can use
automatic Beat Cancel when in SSB or AM mode.
Before
Interfering
tones
After
Receive pass band
Desired
signal
Press [B.C./ MANUAL] to toggle between the Auto
Beat Cancel ON and OFF.
• “B. C.” appears when the function is ON.
• If desired, you can manually control the beat
cancel frequency.
MANUAL BEAT CANCEL (ALL MODES)
Press [FUNC], [B.C./ MANUAL], then turn the
MANUAL BC control to select the single Beat Cancel
frequency manually. You can select the beat cancel
frequency from approx. 300Hz to 3000 Hz by turning
the control. Turn the control clockwise to select a
higher frequency and counterclockwise to select a
lower frequency.
Since the DSP Beat Cancel processes the incoming
signals at the AF stage, strong beat signals may
control the AGC, then weaken the target signal level.
In this case, use the Auto Notch Filter instead, to
remove the beat signal from the IF passband filter.
Note: While adjusting the MANUAL BC control, the transceiver
clicks. This is not a malfunction.
NOISE REDUCTION
(N.R. 1: ALL MODES, N.R. 2: SSB/ CW/ FSK/ AM)
This transceiver provides two types of Noise Reduction
functions (1 and 2) 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 Noise Reduction 1 (Line Enhanced) in SSB
mode and Noise Reduction 2 (SPAC) in CW mode.
Press [N.R./ LEVEL] to toggle between Noise
Reduction 1, Noise Reduction 2, and OFF.
•“ ” or “ ” appears, depending on which
function is selected.
■ Setting the N.R. 1 Level Adjustment
The Noise Reduction 1 (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 N.R. 1 will improve
the S/N further.
While N.R. 1 is ON, you can further adjust the noise
reduction level by pressing [FUNC], [N.R./ LEVEL],
then turn the MULTI/ CH control to select the level
from 1 to 9 or AUTO. The default is AUTO.
■ Setting the N.R. 2 Time Constant
You can change the correlation time for Noise
Reduction 2 (SPAC). When in SSB mode, select
the correlation time that allows you to hear signals
with more 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 N.R. 2 is ON, press [FUNC],
[N.R./ LEVEL], then turn the MULTI/ CH 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.
◆
Only Noise Reduction 1 is available for the sub-receiver.
However, the level cannot be adjusted.