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Re: WHY HAVE MORE THAN ONE CHANNEL?
In article <420e03bd.0@entanet>, braìnbuster@lineone.net (Peter) wrote:
> - unlike > the change from 525 to 625 which *required* that a new set was > obtained. That would be 405 to 635. 405 line VHF transmitters remained active until 1985, broadcasting BBC1 and ITV. -- Paul Cummins - Always a NetHead Wasting Bandwidth since 1981 |
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Re: WHY HAVE MORE THAN ONE CHANNEL?
"Paul Cummins" <agree2pay4uce@spam.vlaad.co.uk> wrote...
> In article <420e03bd.0@entanet>, braìnbuster@lineone.net (Peter) wrote: > > > - unlike > > the change from 525 to 625 which *required* that a new set was > > obtained. > > That would be 405 to 635. According to everything I have been taught and have read, it is 625 lines... 1. Philips service manual. Models: 19TG154A, 19TG156A, 23TG156A. Dated: February 1965. Page 1, Specifications. "625-line Channels 21 to 34 - Band IV 625-line Channels 39 to 68 - Band V" 2. Philips service manual. Models: G20T300, G24T300, G20T301, G24T301. Page 1, Introduction. "The television receivers referred to in this manual are single standard, 625-line, printed circuit hybrid models" 3. Radio Data Reference Book T.G. Giles, BSc (G4CDY) and G.R. Jessop, CEng, MIERE (G6JP) RSGB, 1977. Page 143 - Television standards. 4. RTVES Trade Notes: Manpower Services Commission, 1981. Week 24, Pages 475, 476. Week 24, IC/283/RM (diagram) - BBC Television Waveform. (too many other references to 625-line in this document to list them all) 5. Electronic Systems and Techniques. K.F. Ibrahim. 2nd Edition, 1994. Page 96: "In the British system the number of lines in each picture is 625." (more references on pages 97 to 99) 6. BUSH VCR907 User Guide: Back page, Technical data. "Television System: UK: 625 Lines, 50 Fields" 7. Mathematically: Field frequency = 50Hz Line frequency = 15625Hz As the system is interlaced, with one field giving just half the picture (either odd or even lines), there are only 25 complete pictures per second... 15625 / 25 = 625 lines. 8. Google UK found 37,900 references to our TV system being 625-Line... http://www.google.co.uk/search?hl=en...UK%7CcountryGB So, where do you get 635 from? Regards, Peter http://www.citizensband.radiouk.com/ |
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Re: WHY HAVE MORE THAN ONE CHANNEL?
In article <4211ab48.0@entanet>, braìnbuster@lineone.net (Peter) wrote:
> According to everything I have been taught and have > read, it is 625 lines... Mispront. But 405 lines was the original UK standard for VHF B&W TV. -- Paul Cummins - Always a NetHead Wasting Bandwidth since 1981 |
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Re: WHY HAVE MORE THAN ONE CHANNEL?
"Peter" <braìnbuster@lineone.net> wrote in message news:4211ab48.0@entanet... > "Paul Cummins" <agree2pay4uce@spam.vlaad.co.uk> wrote... > > In article <420e03bd.0@entanet>, braìnbuster@lineone.net (Peter) wrote: > > > > > - unlike > > > the change from 525 to 625 which *required* that a new set was > > > obtained. > > > > That would be 405 to 635. > > According to everything I have been taught and have > read, it is 625 lines... > > 1. Philips service manual. > Models: 19TG154A, 19TG156A, 23TG156A. > Dated: February 1965. > Page 1, Specifications. > "625-line Channels 21 to 34 - Band IV > 625-line Channels 39 to 68 - Band V" > > 2. Philips service manual. > Models: G20T300, G24T300, G20T301, G24T301. > Page 1, Introduction. > "The television receivers referred to in this manual are > single standard, 625-line, printed circuit hybrid models" > > 3. Radio Data Reference Book > T.G. Giles, BSc (G4CDY) and G.R. Jessop, CEng, MIERE (G6JP) > RSGB, 1977. > Page 143 - Television standards. > > 4. RTVES Trade Notes: > Manpower Services Commission, 1981. > Week 24, Pages 475, 476. > Week 24, IC/283/RM (diagram) - BBC Television Waveform. > (too many other references to 625-line in this document to list them all) > > 5. Electronic Systems and Techniques. > K.F. Ibrahim. > 2nd Edition, 1994. > Page 96: > "In the British system the number of lines in each picture is 625." > (more references on pages 97 to 99) > > 6. BUSH VCR907 User Guide: > Back page, Technical data. > "Television System: UK: 625 Lines, 50 Fields" > > 7. Mathematically: > Field frequency = 50Hz > Line frequency = 15625Hz > As the system is interlaced, with one field giving just half the picture (either odd or even > lines), there are only 25 complete pictures per second... > 15625 / 25 = 625 lines. > > 8. Google UK found 37,900 references to our TV system being 625-Line... > > http://www.google.co.uk/search?hl=en...UK%7CcountryGB > > > So, where do you get 635 from? > > > Regards, > > Peter > http://www.citizensband.radiouk.com/ > > |
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Re: WHY HAVE MORE THAN ONE CHANNEL?
"Paul Cummins" <agree2pay4uce@spam.vlaad.co.uk> wrote in message
news:memo.20050215114821.3804C@admin.vlaad.co.uk.. . > In article <4211ab48.0@entanet>, braìnbuster@lineone.net (Peter) wrote: > > > According to everything I have been taught and have > > read, it is 625 lines... > > Mispront. Yes, and I just spotted mine, where I put 525 in place of 405. I must have been thinking of the American system. But, it appeared correctly further down the post... "405 line transmissions" The 405-line system was not really the fist used here in the UK, although it was the World's first public high definition TV service. Prior to 405-line, the BBC used a 30-line, 5 picture per second system (which they raised to 12.5 per second). We desperately needed a better system - Baird came up with a 240-line system and EMI produced a 405-line system. Both were tested for a year by the Beeb, and the 405-line was adopted. Regards, Peter http://www.citizensband.radiouk.com/ |
