[time-nuts] Advice on good reception for radio clocks

Chris Albertson albertson.chris at gmail.com
Wed Jun 27 16:20:53 UTC 2012


One trick that works, place the entire receiver. on a pole (black ABS pipe)
fixed to the back yard fence.  This places it as far from any house or
power line.  I don't think the pole needs to be tall.  8 feet get should be
enough.    Of course now you need a long wire and a pair of RS422 driver
chips and so on.

My next experiment with this will be to use a loop antenna.



On Wed, Jun 27, 2012 at 8:59 AM, Kasper Pedersen <time-nuts at kasperkp.dk>wrote:

> On 06/27/2012 04:04 PM, Tony Finch wrote:
>
> > Are there any basic steps I should take to improve the reception quality
> > of a radio clock? I have a cheap and cheerful DCF77 receiver for
> > connecting to some GPIO pins, but its PPS output is basically noise with
> > maybe a one-second period. Perhaps it's just cheap and nasty.
> >
>
>
> Be careful what you connect the ground of the receiver to.
>
> When I did my DCF77 receiver, my first source of interference was the
> common noise on the output of the supply I was powering it off of.
> I went to a linear power supply, and things were good for a few years.
>
> Then they installed remote-reading power meters in the neighbourhood,
> and DCF77 was completely jammed. The meters talk back on 75kHz with
> ~6kHz bandwidth. Halfway by accident I found out that if I earth the
> receiver well enough, thereby shunting off some of the 75kHz common mode
> signal, I get mostly reliable reception all day.
>
> I would suggest, at least for development, a battery and an optocoupler
> to isolate the receiver section from conducted interference.
>
> Hmm, I do have a Pi.
> And when you have trouble decoding the signal at around 04 in the
> morning, you too will have rediscovered sferics, and the need for a
> filter that handles that.
>
> /Kasper Pedersen
>
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-- 

Chris Albertson
Redondo Beach, California


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