PSIP - Never the right time

Piggie

Super Moderator
#1
I don't know about where you are but here only PBS seems to keep their PSIP clock even close.

Why isn't it set to automatically set it's time? It's a computer program for good grief.
 

Aaron62

Contributor
Staff member
#2
I always thought it was set to the US atomic clock? My question is, what happens if you use that clock for recording with your DTVPal DVR or Tivo DVR?
 
Last edited:

Piggie

Super Moderator
#3
I always thought it was set to the US atomic clock? My question is, what happens if you use that clock for recording with your DTVPal DVR or Tivo DVR?
Aaron, I don't know the protocol that well at all. I can only go from empirical knowledge. From what I have noticed locally, if the time is off on the PSIP clock, then the program show is also off.

So if Jeopardy really comes on at 2pm. But the clock slow, and show 1:34pm when it's really 2:01, the PSIP still shows the what was on at 1:34pm.

Now even more so, is that caused by software in my TV? Or is the station still sending out old data?

I have often thought if I am not alone it would screw up DVRs bad.

Satpro and I discussed this a year ago or so in the Orlando, FL OTA thread at AVS. We never found an answer.

We did do a slight experiment. We called or emailed all the stations that were off and they fixed it pretty quick, but those same stations drifted off again.

I have never seen PBS clock on either OTA PBS be off by more than a couple of seconds, plenty good enough to record.

Back in the day of manually queuing a lot of stuff we had a clock we had to keep set right in Master Control. We had a 10 MHz dipole on the roof to pick up WWV.

We kept our sync generators timed by the satellite feed from Network, so when we switched local to net we didn't roll. Rolling should now be a thing of the past! :)

As far as I can tell from the outside, everything in a modern digital TV studio is timed to something but the stinking PSIP clock for consumers/viewers.

But I wonder how PBS keeps their's right? manually or a different PSIP hardware/software?
 

Aaron62

Contributor
Staff member
#4
Aaron, I don't know the protocol that well at all. I can only go from empirical knowledge. From what I have noticed locally, if the time is off on the PSIP clock, then the program show is also off.

So if Jeopardy really comes on at 2pm. But the clock slow, and show 1:34pm when it's really 2:01, the PSIP still shows the what was on at 1:34pm.

Now even more so, is that caused by software in my TV? Or is the station still sending out old data?

I have often thought if I am not alone it would screw up DVRs bad.

Satpro and I discussed this a year ago or so in the Orlando, FL OTA thread at AVS. We never found an answer.

We did do a slight experiment. We called or emailed all the stations that were off and they fixed it pretty quick, but those same stations drifted off again.

I have never seen PBS clock on either OTA PBS be off by more than a couple of seconds, plenty good enough to record.

Back in the day of manually queuing a lot of stuff we had a clock we had to keep set right in Master Control. We had a 10 MHz dipole on the roof to pick up WWV.

We kept our sync generators timed by the satellite feed from Network, so when we switched local to net we didn't roll. Rolling should now be a thing of the past! :)

As far as I can tell from the outside, everything in a modern digital TV studio is timed to something but the stinking PSIP clock for consumers/viewers.

But I wonder how PBS keeps their's right? manually or a different PSIP hardware/software?
I've seen some threads about this before on other A/V forums and it's been said that some stations just do not care how accurate their PSIP clock is.
 

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