[time-nuts] Time syncing WiFi routers using FM radio

[Glenn Little WB4UIV]

The house standard in some stations are no more than LC oscillators.
As long as the relative timing between signals is constant, you can do 
synchronous switching.
All signals go through as dedicated frame synchronizer that is 
synchronized to house reference.
At the last station that I worked at, our house reference had drifted 
off where it should have been.
To reset it would have required retiming all of the production 
switchers, the cameras and the on air switcher.
There was no cesium standard at the studio nor at the transmitter.
The transmitter was crystal controlled with the crystal in an oven.

Now there is no sync transmitted like in the analog days.
There is a very accurate pilot that can be seen in the signal.
The exciter is synthesized with a crystal bases reference.
Most transmitters can take an external reference, but, the stations that 
I have worked for do not use it.


73
Glenn

On 11/12/2015 2:17 PM, Hal Murray wrote:
>> And the decade before that the hp house standard looked like this:
>
> Has anybody made a graph of the accuracy of house standards over time?  I'm
> looking for something like Moore's Law.
>
>

-- 
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Glenn Little                ARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIV            wb4uiv at arrl.net    AMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI LM   NRA LM   SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
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