In the past I have complained a lot about Loran, which is quite
strong here on the South Coast.
Viewing the band using Spectogram shows that within the bandwidth of
the narrowest CW filter there may be 18 or 20 Loran sidebands. Each
individual sideband is not that strong but is about the same as an O
report slow CW signal.
Some time ago someone suggested (either G4JNT or G3PLX) that there
should no problem in working between these Loran sidebands and
although I did not believe it at the time I now know that it is easy
- I have been doing it for the last couple of weeks.
The following is a description of how the band appears here when
clear of evening QRN
A frequency quoted as .703 means 137.703kHz.
About 8 Loran lines close together .772 - .800
Clear band .769 - .771
Clear band .761 - .763
2 strong Loran lines and noise .755 - .758
Big carrier at .745 with upper sideband noise to .754. (about S6 - 7
in fast CW terms)
Lots of weaker Loran sidebands .709 - .742
Clear band .695-.703
Clear band .681 - 690
Clear band .667 - .675
Frequency bands not quoted have Loran sidebands. The problem with the
Loran is that many of the sidebands are pulsed so that they look like
slow CW signals although I have got to know them now.
I worked Peter, DJ8WL OO this evening (1645UT). On peaks his signal
was strong enough to be audible using a narrow filter, other times he
was down in the noise. Rain static closed in at the end of the QSO.
I copied Dave's PSK31 tests which made some pretty pictures on Gram.
I measured the centre frequency as .653 with sidebands extending to
.671 and .637. Additional single frequency sidebands occured at .702
and .608. (I have saved the WAV files if you want them Dave)
--
Regards, Peter, G3LDO
<[email protected]>
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