[DXLog.net - Support] Decoder freq correction

9A5K 9a5k at 9a5k.com
Mon Sep 30 09:43:39 CEST 2013

Hi all.

It seems that decoder freq correction option made some confusion at some
Option can be enabled/disable in Options->Interface specific->Use decoder
freq correction.

What actually this means?

For example, you're working the station in RTTY contest. Using AFSK mode,
your transceiver is running LSB.
Dial frequency of transceiver is 14.085.0.
Let's say you're listening/working a station using 2Tone decoder which has
default MARK frequency at 1275 Hz.

In case that function above is enabled, band map will show your frequency
as transceiver's frequency
minus (in case of USB it will be plus) MARK frequency.
So, the frequency displayed will be 14085.0 - 1.275 = 14083.7 (actually
14083.725, but this is rounded to one digit).
If you spot this station, spot will be on 14083.7.
Without frequency correction, station will be spotted on 14085.

Now imagine station #2..
That station using MMTTY as primary decoder which by default has MARK
frequency at 2125 Hz (if you press HAM button in it).
If you've spotted previous station at 14085.0, and this second station
doesn't use frequency correction, on double click on
the spot, it will go with transceiver at 14085.0. But, as MMTTY is
listening at 2125, the actual frequency will be
14085.0 - 2.125 = 14082.9 (14082.875)... of course, spotted station isn't
there, so you have to find out where it is hidden.. :-)

If both station are using freq correction, first one will make spot at
Second one, when clicked on the spot, will go at 14083.7 + 2.125 = 14085.8
(14085.825).. so transceiver of the second station
will be at 14085.8, and as mark frequency is 2.125 and mode is lsb, the
actual listening frequency is 14083.7, where first station is actually

I was trying to go through couple of spots during the weekend, and in most
of the cases, frequency in bandmap was same as frequency of the spot.
Also, when I was spotted couple of times, each time frequency was same as
it was on bandmap (which was different than frequency on transceiver's

Chris - 9A5K

More information about the Support mailing list