[email protected] 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
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