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IRIG-B over IP

I am consulting on an application which is transporting IRIG-B over IP. I was asked to design the interface circuit to demodulate the IRIG-B signal and pass the bits to the rest of the system. The same module at the other end has to then modulate an IRIG-B signal from the bits.

I believe the interface details are well understood and should not be a problem. However, as I was discussing this with the customer, they realized that they did not know how to transport the actual time stamp across the network.

You can think of the IRIG-B signal as having two parts; a data part which tells you which second this is and a timing mark that tells you "NOW" is the beginning of the second being described in the data fields. I don't see how they can ever expect to transport the "NOW" across an IP network.

I feel bad because I pointed this out to them and now if they can't figure out how to make the system work, I will lose the job... :^(. I guess that is better than building a board that won't work because of system issues.

Reply to
rickman
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How much delay can you insert in this timing information? I would look at existing applications for synchronizing two realtime clocks. Your box should sync its RTC up to the target computer. Once the source and target have precisely synced RTCs, I would have your box look at the IRIG stream and tell the target end "At exactly 01:23:45.1234567 it will be the NOW moment for second #1234".

Your target will need to buffer the input stream(s) enough to account for worst-case latency on the IP network, but this system seems at least back-of-an-envelope-after-a-hard-night's-drinking doable.

Reply to
larwe

The right thing to do is syncronize to an GPS/NTP clock and then generate the Irig-b loclly.

Reply to
pbreed

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