Dana... Back in the day when out of studio news stories were shot on film, which was then processed at the studio and broadcast from a "film chain" stations would lock their sync generators to the incoming network signal during network hours. That allowed "clean" switching in and out of network programming. When you were in the local programming portion of the day, the local sync generator would not be "looking" at the network signal for reference. That was done because there may have been times when the AT&T microwave network was down for maintenance. Obviously this was before the days of satellite delivery of the network services. You are correct... when the "Live Truck" came on the scene with instant on scene video, etc, the demand for frame syncs at each station went up. Our first frame sync at, WTVJ in Miami, had been used at the Cape for some of the moon shots. It was a huge box, occupying about two feet of rack space! Later frame syncs, would drop in size to 1RU! All those frame syncs were locked to our local master sync generator. At one of our monitoring positions I could compare our local 3.58MHz color burst frequency to the networks and adjust the phase so they were in agreement. This was just a good method of checking our "in house" reference to have it on frequency. If the 3.58 was on frequency, all the other outputs from the master sync generator would be correct. Later sync generators were GPS disciplined. BTW... our later model analog transmitter was GPS locked with one of the original HP boxes. I remember ordering the HP and then WAITING forever for it to arrive. ;-) In the interim, the transmitter ran on it's TCXO box. We had twice yearly frequency measurements done by a monitoring service up the coast. 73 Don W4WJ In a message dated 3/31/2018 11:04:12 AM Central Standard Time, [email protected] writes: I'e always been curious as to why TV stations did not lock at least their in-house equipment to the network feed as a means to avoid spending money on frame syncs. Remote coverage, on the other hand, would of course open a new can of worms.
But compared to the cost of building and powering a TV station and associated studios etc, a Rb or three cost a mere drop in the bucket to buy and maintain, so I'm baffled as to why stations in general did not at use them on a regular basis. Dana On Sat, Mar 31, 2018 at 12:43 AM, Hal Murray <[email protected]> wrote: > > As noted earlier, color burst references were a big deal a long time ago. > > Thanks. I was fishing for something modern, maybe a bit clock out of the > digital receiver. > > I'm assuming that the digital stream is locked to the carrier. That may > not > be correct. > > > -- > These are my opinions. I hate spam. > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
