Problems with time syncs to network

[ChiefOperator]

This thread is a follow-up to my previous thread regarding time syncs. I've installed NTP software on the on-air machine, but so far, I've noticed problems with syncing to the networks. At our hard time syncs, we seem to be off 200-300ms, just enought to cut off the network outcues, usually the last word or at least part of it.

The problem is either my time syncs or the networks syncs. I've used different time servers, different query rates, and even different clients--AboutTime, Tardis and Meinberg. Still the problem continues. Meinberg is a high-quality, very precise NTP client that queries often and shows offset, jitter, etc. My feedback is that everything is synced on my end. Are any of you having problems with syncs? Could the networks be off? My experience is mostly with GPS (and WWV), not NTP software.

Thanks!

 

[frankberry]

The network feeds are delivered by satellite. The time may be correct at the network uplink but by the time the signal reaches your receiver, there is a satellite delay.
Can you program the automation to add a .5 or 1 second delay when you leave the network?

 

[ChiefOperator]

Frankberry-

Thanks. I had thought about the issues of latency and had considered making that change (I believe the C-Band delay is 270ms). But I assumed the networks would correct that problem on their end. That is, understand that latency exists (audio transport and uplink/downlink) and end the program feed a little early (perhaps 500ms) to compensate for all the stations that keep correct time.

Is that how other stations are dealing with this issue? Adjust all programming by 500ms or 1 second? It seems strange that the networks wouldn't compensate for this issue, but as I mentioned, my stations are mostly music and don't have these sync issues.

Thanks

 

[TomZ]

Sometimes there are two bounces to the birds.

Source to control then control to stations.

Double the pleasure, double the fun.

 

[frankberry]

It might be a good idea to contact technical support at the network and ask.
It's very possible that the network hasn't even considered the satellite delay as a potential problem for their affiliates.

 

[Matt]

Another possible solution...ask the network tech people if they have their own time server on the satellite. If you can network that data off the bird it should have the satellite latency accounted for.

Later . . . .

 

[ChiefOperator]

Thanks. I'll follow-up on all the suggestions; all were good. I especially like the idea of syncing to the network time source. I use to do that years ago and sync to the 54:30 closure I believe. Back to the future--sometimes simple is indeed best.

Thanks again..

 

[bossbill]

Like some others have already said... multiple hops, different networks. Talk networks are more unpredictable because you never know how many hops, maybe originating in the host's home, IP to network, up the bird, down, up on another bird.

It's a wonder we're not farther off than we are.

I do use about time as the constant, and for the talk shows on the talk station, add 1-2 second buffers coming out of breaks, usually going into bumper music, but still, going from a network spot into a hard timed break, you get interesting phone numbers.

 

[grich]

You'll probably have to comp for the latency yourself or time-sync from a pulse. It would be cool if a NTP server were built into the sat receiver.

When NBC switched to its current DVB/S2 distribution scheme, they calculated the encode/space transit/decode time at four seconds, with the majority of that time encoding and decoding the 1080i video. The network said, "we're operating on time, and affiliates will have to add on the four seconds."

 

[boiseengineer]

Been using the ABC 500 netcue closure (@ :45) to sync the clocks to :44:48 each hour. Seems to match the network.

 

[DarkStarPDX]

The network said, "we're operating on time, and affiliates will have to add on the four seconds."

This is my experience with most satellite networks, they run "on-time" and the affiliates are expected to compensate as needed. Most feeds ended up being about +2 seconds, but there was an occasional +3 second feed. We just learned and programmed breaks as appropriate.

 

[ChiefOperator]

Okay, Thanks everyone for the comments. It looks like we'll have to compensate for the networks. Time to get to work

 

[chriscollins]

The network said, "we're operating on time, and affiliates will have to add on the four seconds."

This is my experience with most satellite networks, they run "on-time" and the affiliates are expected to compensate as needed. Most feeds ended up being about +2 seconds, but there was an occasional +3 second feed. We just learned and programmed breaks as appropriate.

I have had the exact opposite with my stuff. I sync time via NTP and my talk station is on the money. All my other stations that have hard breaks are also on time.

I am speaking of Citadel, Jones, & Premiere. They appear to do it properly and make sure it is delivered at the correct time or I am just very lucky (which would be VERY unusual).