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

[lists at lazygranch.com]

The ferrite loop antenna receives the magnetic portion of the EM wave. It doesn't have to be a bandpass LC filter. 

The Wellbrook loop antennas are one example of a broadband antenna that receives the magnetic portion. 
 
-----Original Message-----
From: ehydra <ehydra at arcor.de>
Sender: time-nuts-bounces at febo.com
Date: Sat, 17 Mar 2012 16:10:48 
To: Discussion of precise time and frequency measurement<time-nuts at febo.com>
Reply-To: ehydra at arcor.de, Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Subject: Re: [time-nuts] WWVB BPSK Receiver Project? (fwd)

Hi Marek -

I don't know where you are in CZ. I'm on the boarder in DE near PL and 
CZ. The distance to DCF77 is about 450km and if I check the amplitude 
across 24h I see considerable very deep fading effects! I think it is 
useless as a phase-coupled time receiver. At least in specific 
positions. It will loose phase at least for twice the day for approx. 2h 
! That was the report for a ferrite rod.

The other way would be a high-impedance FET-preamp vertical-wire 
antenna. I think this will resist much more fading effects. But it is 
unchecked at the moment. You're welcome to do it.

The benefit of a resonated ferrite rod is the good bandpass filtering 
for local interferers like TV. The FET vertical wire will need heavily 
filtering thereafter. All in the whole dynamice range, of course.


Ferrites can be temperature controlled. They have big spreads in 
parameters anyway! The production procedure is explained in the 
classical book about Ferrites: Snelling "Soft Ferrites".


- Henry


Marek Peca schrieb:
>> That would be 36ns group delay variation if I did the math correctly.
> 
> OK
> 
> And in article P. Hetzel: Time dissemination via the LF transmitter 
> DCF77 using a pseudo-random phase-shift keying of the carrier, 2nd EFTF 
> Neuchatel, 1988., they conclude with timing results of about 2..10e-6 s 
> RMS over ~1000km distance.
> 
> However, I do not know what is the reality and whether such a 
> performance is limited by atmosphere/ground conditions, or whether it 
> could be better within LF band.
> 
>> However, what material are you using for the ferrite? The material can 
>> have a significant tempco.
> 
> In my project, I have used noname rod taken from within DCF77 alarm clock.
> If I will recreate it, I will look for something defined at the store.
> 

-- 
ehydra.dyndns.info

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