Short demo of the hedgehog 405 line video standard converter

Nice diy video converter for the pre-war 405 line UK TV standaard. More info on: electronics.fr... The right TV has still a sync probleem

[@mmwaashumslowww7167]

I remember when I was around 6 or 7 years old ( mid 60s ) watching my grandmother's 405 line tv. I watched the test card for a long time and tried to count the visible lines. She was good to let me do it and knew that it would keep me quiet.

[@GaryKeepItSimple]

BBC 2 started in 1964 on the 20th of April. It was transmitted on UHF and 625 lines. 405 lines was shut down in 1985 in UK

[@brucegilbert7243]

The 405 line system looks significantly better.

[@ianharrison6597]

Thanks for posting this. The Sonys look great. The model on the right I can still feel. We had the United Kingdom version for many years. I watched the Croydon and Crystal Palace (both in London, UK) 405-line switchoffs in 1984 on it. As for Standards Conversion, time to thank Peter Rainger et al at the BBC for analogue 625 to 405 conversion and John Baldwin et al at the IBA for the digital version. For its size and power consumption, I think they would have given the Hedgehog their blessing.

[@RWBHere]

According to the videos it was called 'Hedghog' not 'Hedgehog'. We could still watch 405 lines television until at least the mid-1970's. Apart from the low resolution, it was also susceptible to car ignition noise, which put white dots all over the picture. The 625 line standard hid that noise by the simple expedients of inverting the video modulation and using higher channel frequencies. That made much less visible black dots in the picture instead of intrusive white ones. In addition, car ignition interference tended not to reach into the much higher frequencies of UHF television as much as it did with VHF. There are still a few VHF TV receiving aerials to be seen on older rooftops in Britain, even though they became obsolete more than 40 years ago.

[@electrictroy2010]

The US still uses VHF and yes impulse noise from car ignition or lightning can create noise in the image. (Upto 2009 when it was still analog.)

[@johneygd]

How a 405 line tv could ever look sharper then a 625 line tv , beyond me, unless that source signal was 240 lines and then stretched up on both tv’s, then it is explainitory,

[@allthegearnoidea6752]

I always wondered what the hedgehog looked like. Very impressive.

[@johnsavard7583]

Searching on the lyrics, I was able to identify the video clip being played: Toni Willé of Pussycat is singing her group's biggest hit, Mississippi.

[@johnsavard7583]

Oh, I could have just clicked on "Show More".

[@zetametallic]

Love that song. Year before I was born 1975 I think. It always reminds me of my friends born that year.

[@FrancisLitanofficialJAPINOY]

Does 405 line TV uses AM? French 819 line TV and 625 line SECAM-L used AM, the rest of FM used are PAL-BG, PAL-I, PAL-DK, SECAM-BG, SECAM-DK/K/K1, NTSC-M, PAL-M, PAL-N…

[@Alozhatos]

405 line similar to French L system which uses positive modulation and AM audio.

[@altebander2767]

Hmm, looks like the lines from the video decoder for colour were not connected, so there unfortunately isn't any chance to make it output those experimental System A colour broadcasts. What I'm wondering is if a modern TV could work with those signals, after all in the age of "single chip" TV-sets supporting just about any standards, it could be that some engineer included 405 line just for the fun of it.

[@bobdeverell]

405 gets a bum rap. On this small tv the images should be 'much' sharper. I installed many 405 sets. and on a standard off-the-air signal the 2.75mhz test card bars should be visible. This 405 test card is having problems displaying 1 mHz resolution. Maybe playing from a VHS tape, or is it the camera ?

[@brochanteur8253]

I love TV it's a big window open to the world, but I never open it, it's too windy. .

[@minimaxxl8]

English translation: The cathode ray screen in the service of culture, the television, is a large window open to the world, but I never open it, it makes too much draft. "

[@roachtoasties]

405 looks better, but I think it's about time you upgrade to an HD set. ;)

[@ac-gv1yz]

Who needs HD when you have 405 lines

[@so-vp2qh]

is 405 line progressive scan?

[@minimaxxl8]

Yes, System A, 405 line, is a interlaced video standard.

[@johnsavard7583]

I thought the pre-war British video standard was 240-line Baird, and 405 line was what British black-and-white television was right up until PAL came in around 1968 or thereabouts.

[@peterk75a]

You're right. That's exactly how it was John.

[@johnsavard7583]

Well, I just checked, and I was partly wrong too. The 240-line Baird system and the 405-line EMI system both started to be used at the same time, in 1936, but the 240-line Baird system was abandoned shortly thereafter, so the 405-line system indeed was in use before the war, even if I was right to note that it also remained in use for quite some time afterwards.

[@bobdeverell]

@@johnsavard7583 Hi Jjohn, 240p was abandoned after a couple of weeks in 1936. Believe Baird ran the BBC water tanks used for developing the film, dry. Early prewar sets were dual 240/405. From 1936 onwards all subsequent BBC broadcasts up to 1939 shutdown were 405i.

[@edgeeffect]

Yeah, we had a 405/625 line set in the very early 1970s ... needed to switch to 625 for BBC-2 I think - and BBC-1 and ITV were still on 405.

[@mahmuodaljaf6782]

Waw very cood

[@MirlitronOne]

How should one spell "Hedg(e)hog"?

[@21stcenturyozman20]

If referring to the animal: hedgehog (no initial capital needed; same spelling in US and UK Englishes). In a registrable trade name / trademark, the spelling is entirely up to the business-name owner, so in this instance, Hedghog (initial capital).

[@davidjames666]

both pictures flicker too much, and the quality of both is terrible. all i see are thin lines going across screens within the flicker

[@Witheredgoogie]

That is to do with the camera doing the filming... not the TV sets. A Camera filming an old CRT set had to be synchronized together electronically, which brings about a problem when you filming two different standards as you could only synchronize one.

[@marcusdamberger]

@@Witheredgoogie I'm in former NTSC land, but both those sets should be running at line frequency of 50Hz. So it's all up to the camera to be synchronized. Some cameras/cell phones have options to tell the camera what frequency to choose so you don't get flickering from florescent lights and other sources the derive their frequency from the line voltage AC cycle. Some SLR's can even sync to much higher frequencies like old computer monitors at 75Hz, with options to bump up or down one Hz at a time to get the synchronization just right. i.e. no flicker at all, or slow rolling horizontal bar. I suspect whoever shot this has their camera set to 60Hz. I've often wondered how Japan dealt with their 50/60Hz split during this time in the 50' 60's and 70', most tv's just synced to the line frequency, so if your tuned into a 60Hz NTSC over the air signal, but your TV is running on 100V 50Hz AC, did you see a hum bar slowly going up the screen? Those TV's must have built in much better isolation from the line frequency to the power supply.