Thank you for this. As a member of the Test Card Circle, I do know a fair amount about Test Cards F and J, but what you are showing here adds much information as well. Thank you of course!!
This is a very good video. I have to correct you on one thing. There were two delay lines on a PAL colour decoder. The luminance delay line was not a glass type. It was a a combined coil and capacitor which used long coil with a ground strip inside to form the other capacitor 'plate'. This effectively produced an LC transmission line for the delay. The glass delay line type was used for delaying the chroma signal by one whole TV line for the colour decoding process.
The X (and the game's grid) on the centre of the screen, was placed there to make static convergence of the red, green (and blue) pictures easier, on "delta" type CRTs, which were the first kind of colour CRTs. Around the CRT neck there were four adjustable magnets. Three of the magnets were radial, at 120 degrees apart, mounted on a yoke, and each moved a different primary (TV additive primaries) colour. The blue gun would be switched off, leaving a yellow picture. The red magnet adjusment would move the red gun's screen diagonally from bottom left to top right, the green magnet adjustment would move the green gun's screen diagonally from bottom right to top left. The idea was to get the two colours at the centre of the screen on the X to completely overlap. Then the blue gun was turned back on, and the blue radial magnet (at the top of the yoke, or the bottom if the CRT was installed upside down as in some Thorn made receivers) moved the blue gun's screen vertically. The grid in the 0's and crosses was good for checking this. To complete the central registration, another magnet on a separate assembly could be twisted to move the blue screen horizontally. Once done, there were other controls usually located on a panel which could be accessed from the front of the television, to correctly overlap (dynamic convergence) the three colours in all the surrounding areas. This was done by the circuitry passing adjustable parabolic and sawtooth currents at line and field frequencies through coils in the convergence yoke. The noughts and crosses game, was specifically designed to check central area's RGB convergence. A crosshatch pattern was the recommended way, but these in the sixties and seventies were expensive, and the test card 'F' was a good alternative.
It's great to see your face. When you talk without video I feel like you giving a college lecture and I want to go skeeo. Your face fills in the blanks and makes the videos so much more pleasurable. Nice to see your enthusiasm. Also i woukd never read up about a test card but would always watch your videos as you made a mundane subject interesting. Thank you
Thanks, i tend to stay off camera really because it's easier to video it that way! Now i have OBS setup again i might try doing some videos using two cameras.
Another good one - BBC R&D Monograph 69, where George Hersee explains how Test Card F was designed, and what the features are for: downloads.bbc.co.uk/rd/pubs/archive/pdffiles/monographs/bbc_monograph_69.pdf
Actually, Test Card F was two slides back to back in the same slide frame. A colour one for the centre photo and the edge castellations, and a monochrome one for the patterns. The two pieces of film had to be very carefully aligned.
Did you know that on the original test card F, the colour bars at the top were added electronically. The top of the test card had a similar display to the bottom (green and alternating black squares), except they were cyan and black. The colour bars as I said were added electronically by an engineer, So each day there were different amounts of the cyan and black squares on display, depending on how much they engineer dialled in the colour bars. Fun stuff eh?
@@DextersTechLab That test pattern cannot be made using a normal PAL encoder. It contains some 'wrong' color information that should be displayed as gray by the PAL pahse error compensation. I've seen that appear once and it was quite striking.
@@DextersTechLab Except the BBC's PM5544 had extra frequency gratings, corresponding to the frequencies used in TCF. It was colloquially known as Test Card G. You only tended to see it when the test card was generated at the local region, and the transmission feeds for BBC2 were being used to distribute programme material to the local regions.
"On the updated version known as Test Card J (including widescreen and HD versions), the X on the noughts-and-crosses board is an indicator for aligning the centre of the screen." LOL
Test Card J, from the wiki... "The blocks of colour on the sides would cause the picture to tear horizontally if the sync circuits were not adjusted properly." "A newly added green square at the top of the screen is used to facilitate easier observation of chrominance to luminance delay." EDIT: Ahh, you did already mention that one. ;) "The negative black squares in the left hand step pattern should flash on and off at 1 Hz. This is to aid in the detection of frozen digital links."
I'm thinking the stripes down the side might upset the display if the image is somehow adjusted into the blanking areas, although I'm not sure how that would normally happen, given the relative timing of the Hsync pulses. It can definitely upset digital displays when running via HDMI, though, as I've seen that happen recently on a few projects like MiSTer or the camera board. Even the slightest pulse of image data a bit higher than black level) during Hblank can prevent the receiver getting a lock at all. In this case, my tvONE scaler box.
Make sure to watch this video all the way to the end. I'm waiting for the horror movie where Testcard J comes to life and the evil clown drives a video production engineer insane.
I've only just come across this item. Very interesting as I spent my entire career in Radio and Electronics. From aircraft Radar, Telecommand/Telemetry, HF receiving systems, etc., and finally planning rack installations in a Data Centre. There is a write-up on both Test car "F" & "G" on the BBC Engineering web pages. www.bbceng.info/Information/eng_inf_top.htm. Just search for Test Card. The remainder of the site has some very interesting items particularly under Receivers/Tatsfield. Can anyone spot the "Undulator"...?
It is a skin tone test for colour alignment. They decided to use a child so that the photo would not be subject to changing fashions and gradually appear out of date. The model, Carol Hersee, was the engineer's own daughter.
Thank you for this. As a member of the Test Card Circle, I do know a fair amount about Test Cards F and J, but what you are showing here adds much information as well. Thank you of course!!
And most interesting it is too-well done all round!!
Thank you!
This is a very good video. I have to correct you on one thing. There were two delay lines on a PAL colour decoder. The luminance delay line was not a glass type. It was a a combined coil and capacitor which used long coil with a ground strip inside to form the other capacitor 'plate'. This effectively produced an LC transmission line for the delay. The glass delay line type was used for delaying the chroma signal by one whole TV line for the colour decoding process.
Thanks for the extra info there. 👍
The X (and the game's grid) on the centre of the screen, was placed there to make static convergence of the red, green (and blue) pictures easier, on "delta" type CRTs, which were the first kind of colour CRTs. Around the CRT neck there were four adjustable magnets. Three of the magnets were radial, at 120 degrees apart, mounted on a yoke, and each moved a different primary (TV additive primaries) colour. The blue gun would be switched off, leaving a yellow picture. The red magnet adjusment would move the red gun's screen diagonally from bottom left to top right, the green magnet adjustment would move the green gun's screen diagonally from bottom right to top left. The idea was to get the two colours at the centre of the screen on the X to completely overlap. Then the blue gun was turned back on, and the blue radial magnet (at the top of the yoke, or the bottom if the CRT was installed upside down as in some Thorn made receivers) moved the blue gun's screen vertically. The grid in the 0's and crosses was good for checking this. To complete the central registration, another magnet on a separate assembly could be twisted to move the blue screen horizontally. Once done, there were other controls usually located on a panel which could be accessed from the front of the television, to correctly overlap (dynamic convergence) the three colours in all the surrounding areas. This was done by the circuitry passing adjustable parabolic and sawtooth currents at line and field frequencies through coils in the convergence yoke. The noughts and crosses game, was specifically designed to check central area's RGB convergence. A crosshatch pattern was the recommended way, but these in the sixties and seventies were expensive, and the test card 'F' was a good alternative.
Spent many hours converging TV sets back in the day, almost impossible to get perfect!
It's great to see your face. When you talk without video I feel like you giving a college lecture and I want to go skeeo. Your face fills in the blanks and makes the videos so much more pleasurable. Nice to see your enthusiasm. Also i woukd never read up about a test card but would always watch your videos as you made a mundane subject interesting. Thank you
Thanks, i tend to stay off camera really because it's easier to video it that way! Now i have OBS setup again i might try doing some videos using two cameras.
18:00 This is Vrillon, from the Ashtar Galactic Command, speaking to you …
Test Card F was originally a colour slide (!)
For a while you could download a scanned JPEG of the slide from the BBC's website.
Another good one - BBC R&D Monograph 69, where George Hersee explains how Test Card F was designed, and what the features are for: downloads.bbc.co.uk/rd/pubs/archive/pdffiles/monographs/bbc_monograph_69.pdf
Awesome, thanks! I will have to read up on this.
Actually, Test Card F was two slides back to back in the same slide frame. A colour one for the centre photo and the edge castellations, and a monochrome one for the patterns. The two pieces of film had to be very carefully aligned.
awesome work! And thanks for the clown nightmares now.
Did you know that on the original test card F, the colour bars at the top were added electronically. The top of the test card had a similar display to the bottom (green and alternating black squares), except they were cyan and black. The colour bars as I said were added electronically by an engineer, So each day there were different amounts of the cyan and black squares on display, depending on how much they engineer dialled in the colour bars. Fun stuff eh?
Glad to see you dabble in the avant garde there at the end, haha. Great video as usual, lovely surprise there!
Thanks, made with BPMC hardware!
Only Connect reminded me of this childhood memory.
Thanks for the nightmare fuel!
I'm old enough to remember Test Card C!
What was it like discovering fire?
Loved the horror show at the end, I'm glad I did'nt watch it before I went to bed!
We Love the BBC 2 TV Test Card F and G
And on BBC1 of old too I guess surely?!
I always knew Bubbles the Clown was evil.
Very interesting - here in Australia the Philips PM5544 pattern was pretty much ubiquitous.
Not only in Australia. It's the standard for whole continental Europe.
Yes we often saw the PM5544 pattern too!
@@DextersTechLab That test pattern cannot be made using a normal PAL encoder. It contains some 'wrong' color information that should be displayed as gray by the PAL pahse error compensation.
I've seen that appear once and it was quite striking.
And here in North America, the SMPTE colour bars predominated.
@@DextersTechLab Except the BBC's PM5544 had extra frequency gratings, corresponding to the frequencies used in TCF. It was colloquially known as Test Card G. You only tended to see it when the test card was generated at the local region, and the transmission feeds for BBC2 were being used to distribute programme material to the local regions.
As a kid I honestly thought she was sticking pins in it.
every copy of Test Card F is personalized
😭😭😭
8:50 right half of last line is also missing in analog signal. Any idea what would be the reason?
Probably interlacing.
SDI capture looks great, even after going through the GoogleTube mangle.
"On the updated version known as Test Card J (including widescreen and HD versions), the X on the noughts-and-crosses board is an indicator for aligning the centre of the screen." LOL
Test Card J, from the wiki...
"The blocks of colour on the sides would cause the picture to tear horizontally if the sync circuits were not adjusted properly."
"A newly added green square at the top of the screen is used to facilitate easier observation of chrominance to luminance delay." EDIT: Ahh, you did already mention that one. ;)
"The negative black squares in the left hand step pattern should flash on and off at 1 Hz. This is to aid in the detection of frozen digital links."
I'm thinking the stripes down the side might upset the display if the image is somehow adjusted into the blanking areas, although I'm not sure how that would normally happen, given the relative timing of the Hsync pulses.
It can definitely upset digital displays when running via HDMI, though, as I've seen that happen recently on a few projects like MiSTer or the camera board.
Even the slightest pulse of image data a bit higher than black level) during Hblank can prevent the receiver getting a lock at all. In this case, my tvONE scaler box.
Found a good site. No doubt you've already seen it? hehe
www.radios-tv.co.uk/Pembers/Test-Cards/Test-Card-Technical.html#TCJ-W
The ending was more haunting than The Blair Witch, but then again, so was the movie "Pixels".
I like test card
Make sure to watch this video all the way to the end. I'm waiting for the horror movie where Testcard J comes to life and the evil clown drives a video production engineer insane.
I've only just come across this item. Very interesting as I spent my entire career in Radio and Electronics. From aircraft Radar, Telecommand/Telemetry, HF receiving systems, etc., and finally planning rack installations in a Data Centre.
There is a write-up on both Test car "F" & "G" on the BBC Engineering web pages. www.bbceng.info/Information/eng_inf_top.htm. Just search for Test Card.
The remainder of the site has some very interesting items particularly under Receivers/Tatsfield. Can anyone spot the "Undulator"...?
what's the catch with that middle pic...for non uk lurkers.
It is a skin tone test for colour alignment. They decided to use a child so that the photo would not be subject to changing fashions and gradually appear out of date. The model, Carol Hersee, was the engineer's own daughter.
it's way too compressed ;-)
Perfect nothing.
You are a month late :p
Lol, i am not good for noticing or remembering anniversaries!