How to synchronize two clocks for a robot design?

synchronous clocks

i want to make a set of beacons for a robot to navigate from.
using the same principle of sonar of dividing the distance by the amount of time, the beacons send an ultrasonic pule every few seconds or so and from the distances of all the available beacons the robot can place its co-ordinates on a pre made map which has the beacons on it.

while making a really accurate clock is fairly easy with crystal oscillator's, how do i synchronize them so the both start counting at the same time?

otherwise the robot will start counting the time from a beacon a fraction of a second before the beacon starts sending.

The only way I know to have a synchronous clock is using a mains AC as the clock, but the robot will be battery run.

anyone able to help?

or suggest a better way of doing it?

Re: synchronous clocks

You can use a second communication channel that is faster, like radio or light or wire.

Radio from the robot to the to the beacons would probably be best. That way it could request an acoustic fix when it needed one. Wire between the beacons might also work if the beacons were always laid out in the same positions.

synchronous clocks

thanks, I didn't think of that.

might be a bit of work getting the 2 circuits to transmit at exactly the same time, but it should work.

synchronous clocks

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