Cue Dots

I was led to believe that red phone calls could only be initiated by the nominated contractor, so if Granada were playing something out and realised the planned timings were wrong they would have to call Thames/LWT to make a call.

Compared to the situation nowadays with pres being across production talkback and BBC nations having talkback from Ericsson, the red phone did tend to be more for essential use rather than routine counts in and out of each junction.

Possibly because there's a good chance that not every one of the 14 transmission controllers around the country were hanging on the presenter's every word?

Such jumps were often due to sc/h errors (colour S ub C arrier to H orizontal timing)

Vertical timing errors, of course resulted in a picture roll or splat for the viewer, but were relatively easy to avoid. sc/h not so easy in a dynamic live source switching environment

You can only jump between two sources to have correct sc/h phase every 8 fields (4 frames). It seriously constrained video editing until the 80s, when component video working (notably Betacam) became available

Further reading

https://books.google.co.uk/books?id=bOXGJ-SHiHsC&pg=PA217&lpg=PA217&dq=sc/h+timing+pal&source=bl&ots=z1Dts5bb-o&sig=2UCymbTkua-c1kE5WcNbHXlZGec&hl=en&sa=X&ved=0ahUKEwjvtM2U25jQAhUHDMAKHRIPCwIQ6AEILDAD#v=onepage&q=sc%2Fh%20timing%20pal&f=false

The red phone was never used to perform routine counts in and out of junctions. I'm finding your posts on this a bit confusing. It was used to routinely plan the days programming (and future programme planning in the morning). There were set points during the day to do this, but that didn't preclude controllers talking on the red phone as and when it was considered necessary.

'Yes' Thames and LWT were the ITV nominated contractors and were in charge of running the ITV network across their days, But if Granada (alone) was expecting a programme from Anglia and it didn't seem to be appearing at the right time you would have two options 1. Pick up an outside phone, ring up Anglia's transmission controller and ask them where was such and such programme or 2. Grab the red phone and yell out Anglia, where is such and such programme. The latter more likely to get a quick response. If a company wanted to speak to another company they would just pick up the red phone and talk, if the 'chat' didn't involve the rest of the network they would just turn the volume down a bit. But it was considered bad form if you abused the red phone for trivial matters. Transmissions between individual companies (or part networked programmes) would be discussed during the routine red phone presentation calls that I have already alluded to, this sort of thing was very carefully planned, it wasn't made up as they went along!

Wasn't the Red phone also connect to the transmitter? Im sure were been here before.

You've opened a large can of worms here - as you know! An scH phase error would never be noticed by a monitor or receiver. A studio would always run with an SPG that had the correct relationships between the pulses and naturally scH phase was one of them, but it wasn't essential. If you were lining up (timing) a number of sources into a studio you would naturally get the subcarrier timing spot on and the line timing as close as you could get it. But if you bear in mind the pulses coming out of the studio were always the pulses from a processing amplifier (proc amp) which was always on the end of a studio mixer,then any 'line' timing errors would be masked out. You always tried to get the scH phase on the pulses on the output of the proc amp correct and on the ones I worked on you could certainly adjust it to be correct.

Does it matter? scH phase was not a real practical constraint on video editing unless you were expecting to undertake animation or match field (pick up) editing during a video sequence in post production - a technique where you performed a video edit during a continuous video sequence. If you were doing that you would put the record and playback quad VT machines in 8 field lock up mode which was generally a fraught process unless the machines were correctly set up! Otherwise the machines would be left in 4 field lock up mode and that would almost universally be the normal daily operating mode.

What does this mean? It means the VT machine will lock up only referencing 4 fields and not 8 fields. As a result at the point of lock up and stable pictures, those pictures would be in the correct perfect horizontal picture position (an 8 field lock) or exactly half a cycle of subcarrier moved to the left or right (a 4 field lock). In other words there is a 50/50 chance of the VT machine locking up correctly or completely 180 degrees out from where it might be in the perfect world. The VT machine would be happy with either situation and its time base corrector (TBC) would simply push the picture sideways by half a cycle of subcarrier if necessary to ensure the subcarrier coming off the tape (the actual picture information) matched the subcarrier on the output of the machine itself (station subcarrier).

In layman terms, if the VT machine is in a 4 field (normal) lock mode the pictures on its output would either be perfectly in the right place horizontally or moved sideways slightly by half a cycle of subcarrier. No viewer would notice it.

What was the practical effect in editing? Generally none as 99% of all edits were performed at a shot change on the source material, so at the edit point if the visual material changed AND the picture moved sideways slightly no-one, but no-one would notice it. Except. If you were a bored engineer looking at the programme on a monitor in underscan mode and you put your fingernail against the rhs of the picture as an edit went though you would see the edge of the picture move slightly at an edit point - or least 50% of the time you might!

So, scH phase was not really an issue in the days of quad. The article you pointed to states that scH phase could not be seen on a waveform monitor, perhaps that was true when the article was published but subsequently scH phase could be easily seen on a number of Tek wfm'sand it made life very easy as result. But thinking about it, easy?, well the more the engineers could see and measure scH phases the more it became a hot topic so maybe not!

No.

Even Bungle's???

That was my point.



That contradicts what I have read elsewhere. Thanks.

Ah
I remember a common phrase at Central

"That looked like an invisible edit.........."

as the picture would hopped to the right, 112ns if I remember correctly
The Sony BVT2000P TBC had a video phase knob on the front panel

Yes, I recall it did. What a beast of a device ! Replaced later by four cards that slotted directly
into the front of the BVH-2000 itself, BKH-2350 I think ?

Well if you think about it an edit where the picture moved sideways by half a cycle of subcarrier isn't really an 'invisible edit', it was indeed a commonly used term in analogue days and describes an edit where the PAL 8 field sequence has been maintained over the edit point. There should/would be no picture movement.

As I described above (perhaps not very well) a quad machine, or certainly a top of the range quad machine and not a cut down version, could edit to either 8 field or 4 field accuracy depending on what was required from a post production perspective. 8 field could mean a longer lock up tme for the quad edit pair and that could be frustrating if they were being temperamental. It also meant you were restricted as to where you could perform the edit programme content-wise as you could only perform an edit on the playback material every 8 fields. For 'normal' 4 field editing, and indeed general playback usage the machines would be in 4 field lock up mode - much faster to lock up and so what if the pictures were moved sideways slightly as they were still within the technical spec.

With the introduction of 1" we had timebase correctors with wider correction windows too, this meant they could now start to correct errors greater than a tv line and so it became possible for machines to lock up, and edit, to 2 field accuracy. It you performed such an edit the picture would be pushed up (or down?) a line at the edit point if there was a PAL sequence error. Bit naughty really as potentially you had an extra black line either at the top or bottom of the picture, but again the viewer would never see it. And of course with the general introduction of timecode and very clever editing systems with computers every edit should be an 8 field invisible edit. A long time ago, and I have to admit my memory is getting a bit dim on most of it.