From: "jannsen" <0482183881-0001@t-online.de>
To: rsgb_lf_group@blacksheep.org
References: <151.2bf4d22.290284a6@aol.com>
Subject: Re: LF:  dcf39
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Date: Thu, 25 Oct 2001 13:43:28 +0200
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DL4YHF@aol.com schrieb:
> Hello Uwe and group,
>
> About the "mysterious"(?)  carrier observed on DCF/DBF (I think DBF is their 
> spare transmitter):
> As Uwe wrote:
>
> >sri, Markus, but the screenshot does`nt convince me.
> >sri, Wolfgang, I do not belief in "Kohärenzprobleme". 
>
>
> In a direct mail to Uwe I called it "non-coherent signal",  but it meant 
> exactly the same as Markus (DF6NM) explained here on the reflector a few 
> hours later. I don't think there is any mysterious very-narrow-bandwidth 
> coding.
>
> DCF39 is intended to be received by simple receivers; and the transmitter 
> simply does not care for a coherent carrier just because a few radio amateurs 
> would like to use it as a high-precision reference (hi).
>
>
> The reason for the incoherent carrier signal maybe this (with my basic 
> knowledge ):
> Switching from the "space" frequency to the "mark" frequency in the TX is 
> done when the carrier signal Y(t) crosses zero. After an integer number of 
> full sine wave periods (when Y(t) is zero again), the frequency is switched 
> back again. This will not necessarily be the old phase of the "space" 
> frequency before a data bit. So, as an effect, there is no coherent phase - 
> as explained before. 
>
> You could verify this with an audio phase meter. I did this some time ago and 
> could see the phase meter jump around after every pulse train, but could not 
> find a rule. Maybe the amount of phase shift is simply a result of the count 
> of "ones" in the databits.
>
>
> > I will see my friends at the Radio-Monitoring-Station Itzehoe
> > (RegTP-Aussenstelle) to solve the problem (I make it my problem)
> > by analysing the frequenzy using their equipment (I have been
> > member of the staff).
>
> Please let me know the results.
>
> Good luck,
>   Wolf DL4YHF
>
> (now off to look for Dave G(M)3YXM in simple CW without coherence problems. 
> No kite-friendly WX here at the moment,  nothing but blue sky and sun)


Hi Markus, Wolf, Ko es All.

meantime I have been with my friends at the Radio-Monitoring-Station.

usually we measure the qrg of an A-null by comparing it with a qrg-normal
(caesium standard) using the lissajou figur. but the figur did not come 
to a standstill measuring the mark of DCF39.

my friends did analyse the mark:
it is constantly 10Hz A2-modulated (sinus) and constantly 45dgr Phase-modulated.
no parts of FM. 

I emphasize "constant", i.e. not in the least influenced by the FSK-bursts.
during the 20 min of analysing no keying observed.

my friends did analyse on front IF level (no filter) of the receiving equipment 
(Rhode & Schwarz). it is impossible analysing it on audio level. the results wld 
be incorrect.

there we are.

regards
Uwe/dj8wx