I have three radio controlled clocks in my house, all quite old, which have performed well over many years. However, earlier this year I noticed that they were all showing slightly different times. One has an analogue display and a button that allows me to force it to check itself against the time signal (other than on the hour) and, if necessary, reset itself. The others are small digital clocks which include in their display an indication of the strength of the received radio signal. Both these clock showed that they hadn’t picked up the signal. Replacing the batteries made no improvement and it wasn’t until I placed the small digital display clocks in the garden that they were able set themselves correctly. For years all three have worked well indoors. Why the change?
Move on to today, 29th. March. Last night before going to bed I reset my wristwatch and the bedside alarm clock, both just quartz crystal mechanisms, to British Summer Time. This morning I found that none of the radio controlled clocks had reset themselves to BST, something they had always done in the past. Pressing the button on the analogue display clock made it start searching as normal, but when it stopped and reset itself it showed a time of 12:22 when the time was actually 10:38. A second attempt, and a third, again showed an incorrect time. Eventually it did manage to get the time right.
The only clock in my house to move to BST was the one controlling the heating and hot water. This isn’t radio controlled, working on neither the radio time signal nor on GNSS, because it drifts over time. Instead it has an internal calendar and once the date and time has been set manually it knows when to change between UTC and BST.
Again, placing the clocks in the garden enabled them to reset themselves. Does all this mean that the radio transmission from Anthorn has been reduced in strength?
Luckily my wristwatch agrees with internet time on my computer or I would be uncertain of the time. It tells me that it is now time to get my Sunday lunch into the oven.
Update on 18 May 2020:
Further to my post on 6th April on this subject I now have to report that my radio controlled clocks have started to behave as they should.
For a while, even placing them in the garden didn’t allow them to pick up the signal broadcast from Anthorn. Setting them manually allowed all three of them to agree but they gradually drifted and were in disagreement by a few seconds.
Today, 18th May, I suddenly noticed that all three were in agreement, although the two that have a signal strength indicator were showing no signal. I decided to check them against the pips at midday on the BBC, using FM to avoid the digital delay that makes the pips useless on other transmissions.
All three clocks and the pips coincided with one another, and then I noticed that the signal strength meters were indication a strong signal. All was now well.
But why had there been a problem? The NPL web site gave a list of scheduled maintenance times when the signal would be off air, but none of these coincided with 29th March when none of my clocks re-set themselves to BST, although one sentence states that work carried out between 28th April and 13th May had been completed early and that the service was operating normally from 4th May.