Hello Markus , Alan and Mike ,
Here, on the antenna which is in your direction (K9AY) I do not see anything
abnormal , but I am further (JN06HT)! to see the screen printing with :
http://jpmere.online.fr/Temp/Capt_12.jpg
73 Jean-Pierre f1afj
Markus Vester a écrit :
Hi Mike and Alan,
I believe Mike is right in that the FSK bursts in the upper half of
the band actually do come from DCF39.
Since April 2nd, they have switched to a new Transradio solid state
transmitter, which unfortunately appears to have much less efficient
modulation waveform shaping. The old TX is still used as a backup and
has come on for a few hours from time to time. This is also the reason
for the different reported idle frequencies (138830.03 Hz before,
138830.6 Hz now).
There is a grabber shot on
http://members.aol.com/df6nm2/QRM/DCF39_sidebands_070404.png which
shows the difference of the spectral characteristics. Especially in
quiet conditions, the new burst sidebands can be seen down to about
137.1 kHz and do significantly affect QRSS reception here. I have been
in contact with a person at the German regulatory body
"Bundesnetzagentur", who was involved in the on-site acceptance
testing. He was quite understanding and helpful, but basically said
that the emitted spectrum had been confirmed to be within the
prescribed mask, and there was little he could do to enforce a
reduction of the remaining out-of-band emissions.
Due to the modulation characteristics there are however a few spectral
gaps in the sidebands which could be useful to us. The appended plot
shows a spectrogram between 137.5 and 137.8 kHz (audio frequencies
above 135.5 kHz zero beat). The vertical streaks show visible minima at
137.762 to 137.773 kHz (shown as 2262 to 2273 Hz),
137.620 to 137.655 kHz, and
137.560 to 137.575 kHz.
One possible suggestion would be to move our activity regions for TA
(currently ~137.778) and QRSS (~137.700) down into the first two gaps.
Before we decide to change our habits, it would be interesting to know
how much others in the LF group are affected.
73 and best wishes
Markus, DF6NM
PS: A strong blue trace appeared near 136.319 around 19:20 - Mike's
test signal?
----- Original Message -----
From: "Alan Melia" <[email protected]
<mailto:[email protected]>>
To: <[email protected] <mailto:[email protected]>>
Sent: Monday, November 12, 2007 7:16 PM
Subject: LF: Re: 136kHz DX 11/12 Nov
> Hi Mike I think the data bursts are actually probably from Lakihegy
> (Budapest) 135.5 or thereabouts, which is very strong at night and
shifts
> "into" the band a couple of hundred Hz.
> Loran from Rugby went off in July and it has been a lot quieter
since then,
> but it doesnt seem to be fully running 24/7 yet at Anthorn.
>
> Alan G3NYK
>
> ----- Original Message -----
> From: "Mike Dennison" <[email protected]
<mailto:[email protected]>>
> To: <[email protected] <mailto:[email protected]>>
> Sent: Monday, November 12, 2007 6:06 PM
> Subject: LF: 136kHz DX 11/12 Nov
>
>> I have at last got my station fully running again. Having been off
>> the air for a few months I notice much less Loran QRM which will make
>> CW contacts possible again. But more QRM from DCF39 data bursts which
>> makes QRSS harder.
>>
>> Monitored last night and received the following (using Argo set to
>> 30s slow) :
>>
>> 1800 - 1850 Unidentified station on 137.776kHz (who?)
>> 1900 - 2000 UA4WPF 137.777.2kHz, 'O'
>> 0610 - 0700 XKO 137.777.4kHz One complete call, 'O'
>>
>> Very noisy overnight.
>>
>> Will test my beacon on 136.318.7kHz this evening, but not overnight.
>> Hope to run an overnight beacon later this week. Please let me know
>> if this frequency causes anyone a problem.
>>
>> de Mike, G3XDV
>> ============
>>
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