[time-nuts] Looking for info about first true radio controlled clock

Magnus Danielson magnus at rubidium.dyndns.org
Tue Feb 22 20:12:12 UTC 2011


Hi Jim!

On 02/22/2011 02:34 PM, jimlux wrote:
> On 2/21/11 10:12 PM, Michael Lombardi wrote:
>> I'm trying to determine the first product that could automatically
>> decode and display a digital time code. Digital time codes were
>> added to WWV in 1960 and WWVB in 1965. This was before they were
>> added to any satellite signals, or before they were added to LF
>> stations in Europe, such as DCF77. Telegraphic time codes, of
>> course, were around much earlier.
>>
>
> the IRIG standaards started in the late 50s, and I'm pretty sure that
> they used time code when recording on instrumentation recorders earlier
> than that. You'd record a bunch of analog signals using FM on a
> multitrack recorder, and because the playback speed varies and the tape
> stretches, you need something to recover actual timing.

The NASA 36 bit time-code seems to pre-date both IRIG and WWV broadcast.

The original WWV broadcast where in fact done in the NASA 36 bit time-code.

"STANDARD FREQUENCY AND TIME SERVICES"
http://tf.nist.gov/general/pdf/1746.pdf

I have yeat not found the NASA time code history or for that matter the 
NASA standard for it.

> the first instrumentation recorders were used in the late 40s or early 50s
>
> there's also a famous spread spectrum system used during WW2 with
> identical phono records with random noise, but I think those were sync'd
> by hand.

They where synced by hand, but the turn-tables ran on synchronous motors 
locked to a common frequency broadcast, so the system had an external 
(common) frequency steering.

Cheers,
Magnus



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