Maybe I missed something - this sounds too easy.

Power at the transmitter is effectively unlimited, right? (o.k. 11 watts, but that's still lots) Why not just send a time signal out continuously, and let the receiver read it whenever it wakes up? The transmitted data stream could be a time packet followed by some form of sync pulse - something like $5A5A, then the reciever snychronizes with the next rising edge.

I'm more interested in why the units need that level of sync.

-Denny




> I'm currently working on a design with a specific problem, which I'm
> hoping someone will have come across before.
> 
> Essentially I have several remote circuits, which must remain unconnected.
> They all need to be synchronised within 100 Micro Seconds.
> 
> Essentially we are looking at deploying a beacon transmittor which will
> send out a pulse at known intervals and have low power recievers on each
> circuit which come out of hibernation at the required interval, to reset
> the onboard clocks appropiatly.
> 
> We are looking at achieving 100m range (indoors), however power at the
> beacons is not a significant problem (we have 11Watts available, and these
> are not battery powered). Power at the recievers is crucial, each circuit
> is powered by battery and must be capable of running for a minimum period
> of a year. Physical battery size is not crucial but small is better :)
> 
> Does anyone have any other suggestions how to achieve the required
> synchronisation, or can anyone suggest any suitable radio IC's/circuits
> which could be used as I am stuggling to find anything useful via google
> (must be using the wrong keywords)
> 
> Any suggestions or comments would be greatly appreciated.
> 
> Mat
> 
> 
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