[time-nuts] WWVB BPSK Receiver Project? (fwd)

Poul-Henning Kamp phk at phk.freebsd.dk
Sun Mar 18 18:44:31 UTC 2012


In message <20120318182440.7cb729c2b018b0b2ca5f957b at kinali.ch>, Attila Kinali w
rites:
>On Sun, 18 Mar 2012 13:25:54 +0000

>> Not in my implementation, I have eliminated the input capacitor because
>> the active element is 3cm from the PCB,
>
>Could you explain how the distance of the antenna to the PCB is related
>to a DC block capacitor? And how do you block current flowing from the
>input stage of your amplifier into the antenna?

The input to the amplifier is just a piece of metal, there is no need
for a capacitor in series with it.

The output from the amplifier goes to a transformer which drives a piece
of "twin-ax" cable back to my lab.

The reason for the transformer is that to go really deep in frequency
the usual choke to separate the DC supply from RF signal doesn't work.

I the 'cable-side' of the transformer, in both ends, is centertapped
and that's how I provide power to the antenna.

I have successfully received the Russian "Omega-like" system at
9-15 kHz and I have detected but not demodulated the 86Hz submarine
transmission.

That's DC enough for me :-)

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.



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