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The word dual watch has
been used by many receivers and scanners in the past and is now pretty much
a standard feature. When Icom called their feature dual watch, I think they
really underplayed its usefulness. |
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The traditional dual watch
works in the following way. A receiver goes about its normal business, but
every couple of seconds or so, it hops over to the watched channel to see if
it has become active. If not, it carries about its business. If it breaks
the squelch, it will dwell on that channel so the user can hear it.
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This is a useful feature but has the disadvantage
that its reaction time can be quite slow and messages can be missed. |
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The R20 has priority watch
which is this more familiar feature but it also has Dual watch which is a
completely unique feature amongst any scanner. |
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Inside the R20, there
are in fact two wideband scanners, this allows the R20 to truly monitor two
frequencies simultaneously without any contention. |
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Not all band
stages are replicated so it is not possible to simultaneously listen to all
combinations of frequencies but most common requirements are catered for, in
particular VHF and UHF repeaters. |
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Scrolling through the bands using the
BAND button reveals which bands are possible in
combination.. |
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Here you can see
that the A side can cover eight of the 11 bands in total which the R20
covers. The B side covers six out of 11 bands. Four bands are covered by
both sides so it is possible to listen to two frequencies within the same
band throughout these four bands. This is handy for monitoring both sides of
a duplex channel. |
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All the analogue
broadcast bands are on the A side so it is not possible to listen to for
instance two simultaneous SW broadcasts or say Radio 4 on long wave and
medium wave at the same time. |
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To access
Dualwatch mode, press and hold the DUALWATCH button for one second. The display changes to show
two frequencies and associated parameters. |
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IC-R20 |
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COMMUNICATIONS
RECEIVER |
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Here you see
the R20's screen in Dualwatch mode. Notice that there is a flag saying MAIN
at the top left indicating that the top frequency of 145MHz is the main
frequency and that all key press commands will act on this frequency. |
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Pressing
MAIN/SUB briefly swaps transfers control to the other
frequency. The 'MAIN' flag changes position to denote this. |
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Holding down MAIN/SUB for one second swaps the display around so the
bottom frequency appears at the top and the top frequency appears at the
bottom. This appears to have no effect on function and is purely cosmetic. |
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In a similar
fashion to single band receive mode, you can swap the functions of the
controls around. Instead of swapping the left and right dial around however,
in Dualwatch mode, it swaps the dials with the side up/down buttons.
Instead of the larger VOL flag you see in single
watch mode, you now get a much smaller letter 'V' in the bottom left hand
corner (see above). |
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Press DIAL SEL for one second to toggle between control
function modes. |
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With a 'V' flag
displayed (as shown above) the dials do the tuning and the buttons do the
volume of the MAIN frequency. |
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With a 'D' flag
displayed, the dials control the volume, and the buttons do the tuning of
the MAIN frequency. |
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Squelch can be
set independently for each frequency with the controls in either
configuration but I personally find it easier to do it under the 'V' mode.
Simply hold the SQL button and rotate the appropriate dial. As
with tuning, it's left dial for the top and right dial for the bottom
frequency. |
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In Dualwatch mode, the left hand dial always applies to
the top row and the right dial always affects the bottom row.
This applies equally to frequency, volume or
squelch. |
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You can indeed
operate memory channels in Dualwatch mode. This is done in a similar way to
single watch mode by briefly pressing
MR S.MW .This will act on whichever frequency row is currently
selected as the main frequency.
If a memory
channel comes up blank when browsing through with a dial, that is possibly
because it is outside the scope of coverage of the side you are trying to
access it on (see table above) |
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You can even
have two scan routines running simultaneously, either in
VFO mode, memory mode or a combination of both.
Scanning is initiated in a similar way to single watch mode using the MODE SCAN button. |
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