Is it possible to modify radio-controlled clocks (so-called "atomic" clocks, like https://www.amazon.co.uk/Wall-Clocks-Radio-Controlled/s?ie=UTF8&page=1&rh=n%3A376322011%2Cp_n_feature_keywords_browse-bin%3A1249834031) to synchronise to an arbitrary (local) time signal rather than the standard time signal (i.e. MSF in the UK, WWVB in US, or any number of other time signal stations across the world)?
As I see it, this would involve two parts:
a.) Adjusting the radio receiver in the unit to listen on a different radio frequency of a locally-provided time signal rather than the default frequency
b.) Broadcast the desired time signal in the expected format on that frequency.
I've had a look at the signal standard, and I think I'd be able to broadcast a signal as described here http://www.npl.co.uk/upload/pdf/MSF_Time_Date_Code.pdf using a handful of components and an Arduino.
However, I'm not really sure how I'd approach adjusting the receiver as described in a.) – or whether there's a better approach I could take? (or other flaws in my plan I haven't considered), and my Google-fu has not brought up any useful resources to suggest others having achieved this in the past. I wondered whether I'd even need to change the frequency, or whether producing a local signal on the same frequency would have sufficient power to "override" the official time signal?
Any advice would be gratefully received!
To further explain my purpose; I'm not trying to improve the accuracy – I'm trying to broadcast and display an arbitrary local "stopwatch" time, unrelated to whatever the actual current time might be. (From asker's asker's clarifying comment)
Best Answer
These commercial products are very difficult to adapt for other purposes:
Data rates are very slow, often one bit-per-second.
Clocks often only "update" periodically, (once an hour? a few times per day?)
Frequency of operation is very precise, perhaps crystal-controlled.
Highly integrated for low cost.
Am mostly familiar with WWVB, and have programmed a microcontroller to receive its 60 kHz signal. The project is not recommended for novices.
Data transmission via radio over short distances is a common desire served by RF modules...the transmitter accepts digital input, and the receiver outputs a digital replica. Ensure that the operating frequency and power are appropriate for your region.