[time-nuts] How accurate are cheap radio controlled clocks?

Dr. David Kirkby david.kirkby at onetel.net
Sat Jun 25 20:53:10 UTC 2011

On 06/25/11 08:45 PM, Eamon Skelton wrote:
> On 25/06/11 20:19, Dr. David Kirkby wrote:
>> I've got one of the cheap radio-controlled clocks? I was listing to
>> radio 4 the other day and herd the time signal. The radio controlled
>> clock was about 3 seconds off. I was a bit surprised it was so far off.
>> I'm just wondering how accurate these things are.
> Typically better than 1s. If there is interference or the radio is
> disabled,
> it won't be able to receive the time signal. Switch mode PSUs and CRT TVs
> or computer monitors can interfere with the 60kHz time signal.

I don't think there's an SMPS nearby, but there was a 100 W amateur transceiver.

> The clocks with an LCD display usually have an indicator which shows
> signal strength if the clock successfully updated in the last hour.
> If you have reception problems, try moving the clock. The built-in
> ferrite rod is very directional.


> Were you receiving Radio 4 on LW or via a digital service. You could
> easily see a 3s delay on digital radio or TV.

198 kHz longwave - using a Kenwood HF transceiver which has general coverage 

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