Yep. This Photo was taken one second past 22:33 on 26 July 2006
In 1976(?) Australia's TRL (Telecom Research Labs) developed a method of distributing epoch time, Civil Time values and Daylight saving indicators from their Caesium references at their Clayton Labs. This used a 'proprietry' serial code over what was then a standard 200 baud modem channel. It was claimed to give 500uS accuracy to epoch, although I belive this would have required local calibration of the transmission delay to a portable Caesium standard. Still not bad though.
I think the original Civil Time Receivers as described in Rpt 7495 were built at TRL. Later model 206 and 206D were built by GED (later to be RME). The receivers have a modem input and a time display, as well as connectors for outputing BCD values of Day of Year, Hour , Minute and Seconds values. The 206/206D also have an RS232 acsii time stream output.
Civil Time Receivers were used to sync the speaking clocks, computer systems, and ultimately provided the time 'pips' on the hour for Radio stations. I'm pretty sure I've seen Civil Time Receivers in pictures of VNG.
The Civil time receiver I have is a RME 206D. It has an internal battery backed real time clock to keep time
when the modem signal is removed, so once its set from line it acts as a rather large clock.
I wrote some code to generate bursts of the CSK-1186 format signal from my desktop PC which is synced off GPS so I
now
have a clock that is initially set of a reasonable source. I have trimmed the internal clock to a couple of PPM so
it
will be interesting to see how bad temperature related drift is.
I have also added a piezo element across the 1mS epoch strobe so that the box now 'ticks' every second - makes it
easier to check against other clocks.
All in all another wonderful example of 'lost' technonogy. I suspect my Civil Time Rx is one of the last 1/2 dozon or so actually keeping time....
Yep. This Photo was taken one second past 22:33 on 26 July 2006
