Dawn of Television and 405 vs 625 vs 525

Mike 1972

watty wrote: »

By your logic we should have had 405 Colour

Tsk Watty nobody calls it that anymore. Its 377i now

Mind you several channels on the UK's wonderful MPEG 2 based system are running at half resolution (288i) so 405 colour would actually be an improvment in these cases.

Mike 1972

watty wrote: »

ITV wanted 405 colour and did some demos.

The Beeb were toying with the idea of 405 colour for a while as well and trials were done with 405 versions of NTSC PAL and even SECAM The BBC and ITV couldnt agree on which was best.

watty wrote: »

625 standard was published in 1946 and in widespread use by 1948.

Ive heard dates from 1941 to 1950 quoted by various sources. Not sure who is correct. Some suggest 625 was basically NTSC adopted for 50 HZ mains with a slight tweak in the line frequeny and first used in the American sectors of post WW2 Germany but this doesnt explain how the Soviets also ended up using it ?

watty wrote: »

Infact the UK should not have started 405 after the war. They knew it was wrong and there was less than 1000 operational pre-war 405 sets.

Again different sources give different figures on this one. Some claim there were as many as 20,000 (405 line) TV sets in England in 1939. If this is the case what happened to the other 19000 + ?

watty wrote: »

It was crazy that Ireland did ANY 405 in 1962. I'm glad to see we are not repeating that stupidity.

Given the number of 405 only sets in the country (and the cost/impracticality of replacing/modifying same) at the time It actually made sense at the time. One cannot just apply the logic of today to the technology and economics of the 1960's

Incidently Id like to learn a bit more about the origins of System I but maybe thats one for the "History" board.

Dual MPEG4+MPEG2 (3x to 4x as much spectrum)

Actually as a short term temporary measure it might make some sense to duplicate the RTE multiplex (but not the others) in MPEG 2 on Some East Coast and Border transmitters (same as was done with 405 line back in the day) but only until say 2015

watty

Mike 1972 wrote: »

Ive heard dates from 1941 to 1950 quoted by various sources. Not sure who is correct. Some suggest 625 was basically NTSC adopted for 50 HZ mains with a slight tweak in the line frequeny and first used in the American sectors of post WW2 Germany but this doesnt explain how the Soviets also ended up using it ?

There are only certain numbers of lines possible for each frame rate. The mains frequency chosen rather than film frame rate for two reasons.
1) Avoiding strobe effects with studio lights
2) Any mains ripple / hum effects on picture would be static rather than running through it.

An interlaced system requires accurate positioning of scanning lines so the frame and line timebase are in a precisely related. The frame rate is produced by whole number division of line rate. In the 1930s this division process could only with numbers less than 8. The number of lines was odd because of 2:1 interlace. The 405 line system used a frame rate of 50 Hz ( and a horizontal one of 10,125Hz (50 × 405 ÷ 2) 405 being derived from (3 × 3 × 3 × 3 × 5)

Thus 525 line rate is 60 x 525 ÷ 2 = 15,750
A 50 Hz version of 525 is possible, logically that is what a US in Europe transmission would have used.
50 x 625 ÷ 2 = 15,625 Hz, slightly lower frequency.

Again different sources give different figures on this one. Some claim there were as many as 20,000 (405 line) TV sets in England in 1939. If this is the case what happened to the other 19000 + ?

Many out of service or out of coverage.

1946 had one transmitter. Alexandra Palace
1949 2nd transmitter added in Sutton Coldfield.

Given the number of 405 only sets in the country (and the cost/impracticality of replacing/modifying same) at the time It actually made sense at the time. One cannot just apply the logic of today to the technology and economics of the 1960's

I and many others don't thing so. It wasted Millions. The UK had to change over anyway.

watty

Some links

http://tx.mb21.co.uk/
http://www.bvws.org.uk/405alive/
http://www.aerialsandtv.com/suttoncoldfieldtx.html
http://www.transdiffusion.org/emc/baird/tvoff.php

And wikipedia, though some dates errors on its 405 history.
http://en.wikipedia.org/wiki/History_of_television

http://www.statemaster.com/encyclopedia/Television-systems-before-1940
The V rocket test ranges used some kind of Analogue Cable mono HDTV

How and why particular line rates were chosen

Because an interlaced system requires accurate positioning of scanning lines it is important to make sure that the horizontal and vertical timebases are in a precise ratio. This is accomplished by passing the one through a series of electronic divider circuits to produce the other. Each division is by a prime number. Therefore there has to be a straightforward mathematical relationship between the line and field frequencies, the latter being derived by dividing down from the former. Technology constraints of the 1930s meant that this division process could only be done using small integers, preferably no greater than 7, for good stability. The number of lines was odd because of 2:1 interlace. The British 405 line system for example used a vertical frequency of 50 Hz (Standard AC mains supply frequency in Britain) and a horizontal one of 10,125Hz (50 × 405 ÷ 2) Interlacing is a method of displaying images on a raster-scanned display device, such as a cathode ray tube (CRT). ... In mathematics, a prime number (or a prime) is a natural number which has exactly two distinct natural number divisors: 1 and itself. ... Hz or hz may mean: Herero language (ISO 639 alpha-2, hz) Hertz, unit of frequency This is a disambiguation page — a list of articles associated with the same title. ...

* 2 × 3 × 3 × 5 Gives 90 (not interlaced)
* 2 × 2 × 2 × 2 × 2 × 3 Gives 96 (not interlaced)
* 2 × 2 × 3 × 3 × 5 Gives 180 (not interlaced)
* 2 × 2 × 2 × 2 × 3 × 5 Gives 240 (Used for the experimental Baird transmissions in England -not interlaced)
* 3 × 3 × 3 × 3 × 3 Gives 243
* 7 × 7 × 7 Gives 343 (Early North American system also used in Poland before WW2)
* 3 × 5 × 5 × 5 Gives 375
* 3 × 3 × 3 × 3 × 5 Gives 405 (Used in Britain Ireland and Hong Kong before 1985)
* 2 × 2 × 2 × 5 × 11 Gives 440 (not interlaced)
* 3 × 3 × 7 × 7 Gives 441 (Used by RCA in North America America before the 525 standard was adopted and widely used before WW2 in Continental Europe with different frame rates )
* 2 × 3 × 3 × 5 × 5 Gives 450
* 5 × 7 × 13 Gives 455 (Used in France before WW2)
* 3 × 5 × 5 × 7 Gives 525 (A compromise between the RCA and Philco systems Still used today In America and parts of Asia)
* 3 × 3 × 3 × 3 × 7 produces 567 (used for a while after WW2 in the Netherlands)
* 5 × 11 × 11 Gives 605 (Used experimentally by Philco in North America before the 525 standard was adopted)
* 5 × 5 × 5 × 5 gives 625 (Still used today in most parts of the world)
* 3 × 3 × 7 × 13 Gives 819 (Used in France in the 1950’s)

Even some digital TV line rates (i.e. 480 and 576) are based on the number of active lines in the 525 and 625 analogue video standards which preceded them.

How and why particular frame/field rates were chosen

Since the mid-1930s it has been standard practice to use a field frequency equal to or a submultiple of the AC mains electric supply frequency 50 Hz in most countries (60 Hz in others) because studio lighting generally uses alternating current lamps and if these were not synchronized with the field frequency, an unwelcome strobe effect could appear on TV pictures. Secondly the smoothing (filtering) of power supply circuits in early TV receivers was rather poor and ripple superimposed on the DC could cause visual interference. If the picture was locked to the mains frequency, this interference would at least be static on the screen and thus less obtrusive. By the 1930s most countries had standardized their public electricity supplies on either 50Hz or 60Hz and this heavily influenced the choice of frame rate (12.5 25 or 30 fps)


Other considerations

The bandwidth required to transmit a television signal increases as the field rate and particularly as the line rate increases. In the interests of economic use of the available radio frequency spectrum, it is important that the bandwidth of the TV signals does not become too large; a more pressing consideration in the 1930s was that given the limits of the technology of the day, wide-bandwidth signals were very difficult to handle within transmitter, receiver and antenna circuitry. Thus while it may have been desirable to maximize picture quality by using very high line and frame rates, in practice there were limits to what could be used. This article does not cite any references or sources. ...


The THEORETICAL bandwidth requirements of the different standards are as follows

* (number of lines * frame rate) * (number of lines * aspect ratio) /2
* 405 line (405 * 25) * (405 * 4/3) /2 = 2733750 Hz or 2.75 MHz (5:4 aspect ratio pre-1950)
* 525 line (525 * 30) * (525 * 4/3) /2 = 5512500 Hz or 5.52 MHz (29.98 Hz field rate with Colour NTSC)
* 625 line (625 * 25) * (625 * 4/3) /2 = 6510417 Hz or 6.51 MHz
* 819 line (819 * 25) * (819 * 4/3) /2 = 11179350 Hz or 11.2 MHz

In practice most broadcast TV systems use slightly less video bandwidth sacrificing some horizontal resolution in the process.

Sam Russell

The 405/625 difference had other implications. The decision by rte to broadcast in 405 near the ni border meant that people could receive ni tv. The UK left 405 trnsmission going to reserve the vhf band, long after no one was watching. We had to put up with dual standard tvs. The uk chose to use the pal colour system, but not the same as others, the sound channel was on a different sub carrier.

So we ended up with special sets, with vhf tuners, and PAL-i, whereas the uk had uhf only sets with pal-i. The rest of europe (except France and Russia who used secam) with pal-b. I do not know why.

If you look at modems, the us used a different standard to europe at 300 baud, but everone used the same at 1200. Now noone uses them atall - we use broadband, and wifi. The same will happen with the tv. In a few years all tvs will use mpeg4 and db2, possibly with a sat receiver. Currently all european tvs have ci slots.

watty

The UK sold Dual Standard TVs before 1967 in readyness for 625.

I remember ours. It had turrent tuner for VHF and continious scale and pointer with Tuning knob for UHF, like a radio.
A giant changeover switch the length of the set to changeover. I remember the 1st day we got BBC2. Even though still B&W such a difference in picture and sound quality.

In the early 1970s I repaired many dual standard sets by hardwiring/soldering the switch in the 625 position after cutting knob / lever linkage.

UTV started in 1958, so I don't think we had TV before then. I was very small when my sister was born in 1960, I'm sure we had TV before then.

Many countries, not just UK used PAL-I, it allows 5.5MHz video bandwidth. PAL-B only allows 5MHz bandwidth. PAL-I was the highest quality PAL.

PAL-B allowed a 2nd sound subcarrier.

Nicam puts a 6.5MHz carrier on PAL-I, making channel wider, but still within 8MHz
http://en.wikipedia.org/wiki/PAL

Mike 1972

I think we should make clear for anyone who may be confused that this thread is a split off from another thread dealing with DTT standards

Sam Russell wrote: »

The 405/625 difference had other implications. The decision by rte to broadcast in 405 near the ni border meant that people could receive ni tv.

And by the same token being on 405 made it easier for people in parts of NI to recieve RTE

Sam Russell wrote: »

We had to put up with dual standard tvs.....So we ended up with special sets, with vhf tuners, and PAL-i, whereas the uk had uhf only sets with pal-i.

So did a lot of people in the UK. London got 625 line TV in 1964 but Fermanagh didnt get it until 1978 and there were UHF coverage blackspots throughout the UK which didnt get relays until well into the 1980's. In the meantime anyone living in these areas would have been advised to buy dual standard sets in order to make the upgrade to 625 when it became available.

Sam Russell wrote: »

The uk chose to use the pal colour system, but not the same as others, the sound channel was on a different sub carrier..

Actually PAL-I was adopted in Ireland (1961/2) before the UK (1964) however the exact timings and rationales are a bit unclear. Probably RTE were aware that the UK were likely to use PAL-I and thought it best to maintain compatability with the UK as much as possible ?

Sam Russell wrote: »

The rest of europe with pal-b. I do not know why...

The PAL-I system is considered superior to PAL-B in that the greater audio/video seperation means less "Vision on sound" buzz and the slightly wider video bandwidth means slightly sharper pictures however the PAL-B system VHF channels are only 7 MHZ wide making for more efficent spectrum usage. Strange thing is the Russian system D is even better than Systems I (or L) and could have been used with PAL (as is done in China) in UK/Ireland but for some reason wasnt.

Sam Russell wrote: »

(except France and Russia who used secam)
...

Actually most of the Eastern Bloc used SECAM as well (most of these reverted to PAL-B after 1989) The main exceptions were Yugoslavia (PAL and East Germany (Mainly SECAM B but some experiments with SECAM D and PAL

watty wrote: »

There are only certain numbers of lines possible for each frame rate. ...

Still doesnt explain how a system allegedly (but plausably) devised by engineers in the US Sectors of post WW2 Germany ended up in use (albeit with some variations) throughout Europe on both side of the Iron curtain

watty wrote: »

Many out of service ...

So how did 19,000 TV sets end up irreperably out of service during WW2. It was hardly through excessive use ?????

watty wrote: »

or out of coverage.
1946 had one transmitter. Alexandra Palace
1949 2nd transmitter added in Sutton Coldfield....

Doesnt really explain much. Alexandra Palace had been on air 1936-39 was off (bar some jamming of Luftwaffe radar and navigation beacons) for a few years and resumed in 1946. How would anyone who had coverage in 1939 not have it in 1946 ?

watty wrote: »

I and many others don't thing so. It wasted Millions. The UK had to change over anyway.

Certain practicalities need to be considered here:
1) Widespread ownership of 405 only sets in parts of both the Republic and Notherrn Ireland where cross border reception possibile
2) Upgrading in order to recieve new standards only really possible by replacing a TV set at a cost of at least a couple of months wages. (Set top boxes didnt exist) Modification of existing sets extensive and therfore uneconomic in many cases
3) Collecting a TV licence from owners of 405 only sets (In the absence of an Irish 405 line service) would have probably caused many practical (not to mention political) difficulties
4) In 1961 when RTE starting up there were thousands of 405 line sets (unlikely to be replaced until end of life cycle) but (initially) only a small number of 625 line only sets. As a dual funded (licence fee/commericial) service the initial audience for a 625 line service would have been tiny and despite the extra costs duplication of line standards would have made economic sense.

watty

The USA didn't design 625, it was proposed in Russia in at least 1944.


Have you seen 1930's radio gear? I have and repaired it. The 1938 sets very poor compared to a 1949 / 1950 set even. I agree, the conflicting figures and claims about 1946 set population is confusing.

SECAM came in two flavours, FM subcarrier and AM subcarrier. The FM version created crawling artifacts. Much inferior to PAL, which was a very simple change to NTSC.

I've lost count how many versions of SECAM there was!

Whatever about 405 (ended 1985), the 819 line mono French system ended a year later and crazy!

Mike 1972

watty wrote: »

The USA didn't design 625, it was proposed in Russia in at least 1944.

Interesting. I would have thought that Soviet engineers would have been entirely preoccupied with more pressing priorities at the time ?

I've lost count how many versions of SECAM there was!

At least 5.
Secam 1 and (I think) 2 were AM based
Secam 3 was FM based
Secam 4 (AKA NIR) emerged in the late sixties but was considered too late to be a contender

Later Secam 3 was split into SECAM V and SECAM H. The latter being a more recent variant designed for improved compatability with teletext (some countries experimented with hybrid variants for a while)

watty

Some interesting discussion here
http://www.vintage-radio.net/forum/showthread.php?t=36027

The 1946 timing is confirmed in a comment I have since found at:

http://www.bvws.org.uk/405alive/faq/405_hist.html

The rest of Europe opted for 625 lines, a system devised in 1946 by two German engineers, Möller and Urtel (it appears that the Russians came up independently with a very similar system and if you had set anyone else the problem - to Europeanise the American 525-line standard - they would have come up with something pretty similar). In Geneva a Mr W. Gerber proposed this as a European system and it has remained in use until the present day.

It seems, then, that the Russian version of the 625 line system was more the result of synchronicity than imitation. And that the Russian choice of 6 MHz video bandwidth could simply have been an engineering decision, there being no precisely "right" number for this parameter.

So Germans in 1946 may have Europeanised the US 525, but the Russians had also worked on this since 1944.

(The Soviet Union in 1944 was a big place, there was all kinds of strange research!)
There is another wacky wiki article on Analog HD, doesn't mention the German HD CCTV in Penemund V2 rocket range.
http://en.wikipedia.org/wiki/Analog_high-definition_television_system

Not sure if I posted this:
http://www.pembers.freeserve.co.uk/World-TV-Standards/index.html

watty

From http://www.bvws.org.uk/405alive/info/and_finally.html

Even though Yorkshire Television started in the 405-line era, its cameras were 625 lines from the start. When the station opened the cameras were Marconi Mk 7 (four-tube) colour ones, used in monochrome. All tubes were fitted in fact, but a mirror put all the light down the luminance channel. Soon afterwards they started producing programmes in colour, though only a monochrome signal left the studios. Initially the 625-line signal was converted to 405 lines using an on-site converter. With the coming of the public 625-line service the standards converter was moved to Emley Moor (this converter is now in the Bradford museum).

Victorian experiments
http://www.diycalculator.com/sp-console.shtml

Sam Russell

watty wrote: »

The UK sold Dual Standard TVs before 1967 in readyness for 625.

I remember ours. It had turrent tuner for VHF and continious scale and pointer with Tuning knob for UHF, like a radio.
A giant changeover switch the length of the set to changeover. I remember the 1st day we got BBC2. Even though still B&W such a difference in picture and sound quality.

I remember watching BBC2 when it launched in colour. I beleive the first programme (as opposed to news/ announcements) shown in colour was 'The Black and White Minstrel Show'. I am not kidding. It was a music and dance show with girls in full skirts and men with blacked faces. Despite its title it was a very colourful show. It is nice to see someone in the Beeb had a sense of humour and history!

watty

Colour was out quite a while when we got it. But I remember the soap powder adverts were still in B&W!

Technically I think after Colour introduced the B&W minstrels had "browned" faces

Sam Russell

watty wrote: »

Colour was out quite a while when we got it. But I remember the soap powder adverts were still in B&W!

Technically I think after Colour introduced the B&W minstrels had "browned" faces

The faces were black, not brown as far as I can remember. It was referred to as 'blacking'. White male dancers had boot polish on their faces and white around their eyes and mouths, like a 'Robinson's Marmalde' Golliwog. Oops can't say that anymore. They had to get rid of the golliewogs. Oops. Can't say Black anymore, or golliewog. Oops can't black-up anymore. Oops. Oops.

Sorry. Ooops.

watty

There was an Radio Times article. And not jet black on our TV. Maybe your set needed adjustment
True before Colour transmission version it was actual blacking.

Iv'e seen more than one version of the Jolson Story.

Anyway an interesting chat today.

Sam Russell

watty wrote: »

There was an Radio Times article. And not jet black on our TV. Maybe your set needed adjustment
True before Colour transmission version it was actual blacking.

Iv'e seen more than one version of the Jolson Story.

Anyway an interesting chat today.

The point I was trying to make was the title of the show. Whatever they had on their faces could not be used now. Even Nelson Mandela is referred to as an 'Afrcan-American' by the USA media.

Progress, you could not make it up.

Mike 1972

watty wrote: »

The UK sold Dual Standard TVs before 1967 in readyness for 625.

How long before (BTW it was 1964 when 625 started 1967 was the date for commencment of regular colour broadcasts although there had been tests since the mid-late fifties)

Many countries, not just UK used PAL-I

Ireland and South Africa but where else ?

PAL-I was the highest quality PAL.

Apart from PAL -D (China etc)

zilog_jones

Mike 1972 wrote: »

Ireland and South Africa but where else ?

Macau, Hong Kong and the Falkland Islands.

Mike 1972

zilog_jones wrote: »

Macau, Hong Kong and the Falkland Islands.

Suppose one can also mention the BFBS stations in Germany and elsewhere

watty

Possibly
Angola, Botswana, Lesotho, Gambia, Mozambique, Namibia, Saint Helena (Ascension and Tristan da Cunha), Tanzania - Unguja Island (formerly Zanzibar) and Pemba , Pitcairn.


Countries now DTT only that had some kind of PAL (wikipedia)
Countries and territories that once used PAL
Country ↓ Switched to ↓ Switchover completed ↓
Andorra DVB-T 2007-09-2525 September 2007
Finland DVB-T 2007-09-011 September 2007
Luxembourg DVB-T 2006-09-011 September 2006
Netherlands DVB-T 2006-12-1414 December 2006
Sweden DVB-T 2007-10-1515 October 2007
Switzerland DVB-T 2007-11-2626 November 2007

Also Berlin.


I had thought Malta, Australia and N.Z. but I was wrong

http://www.dvd-replica.com/DVD/palnations.php
http://www.paradiso-design.net/TVsystems_worldwide.html

Technically The Channel Is. and Isle of Man are not UK

Antenna

Mike 1972 wrote: »

Actually PAL-I was adopted in Ireland (1961/2) before the UK (1964)

Was PAL actually chosen in 1961/2 (even though in wasn't actually introduced by RTE until the early 70s?

watty

I didn't realise this till a few days ago, but allegedly that is why it's called PAL-I, as we adopted it 1st (for 625line mono in 1962, UK two years later!). Even though initially we didn't have colour...!

The main difference is the video bandwidth and the audio carrier offset. There is no separate standard for 5.5MHz Video + 6MHz sound offset and no colour @ 625lines x 25i

Mike 1972

I didn't realise this till a few days ago, but allegedly that is why it's called PAL-I, as we adopted it 1st (for 625line mono in 1962, UK two years later!). Even though initially we didn't have colour...!

Surey the Germans had PAL before anyone else seeing as how they invented it ?

In the UK there were discussions about which colour system to use as late as 1965

In 1962 RTE (or "TE") werent using PAL they were using "CCIR System I" (and A) Remember the basic transmission standard and the colour system are not the same thing

Some might argue that NTSC is a bit of a grey area since NTSC-1 (Subsequently AKA "CCIR System M") is transmission standard amd NTSC-2 is a color system but where does leave Brazil (PAL-M)

Technically The Channel Is. and Isle of Man are not UK

Technically Berlin is not a country (although technically it wasnt part of Germany between 1945-90 even if the East Berlin authorities thought otherwise)

watty

Sorry... Confusing! PAL wasn't even invented till 1963

Yes the Russians and Germans both had 625 lines 1st.
CCIR-A = 405 lines
CCIR-B = 625 line standard (but not the original one for political reasons?)
“parent” 625-line broadcast standard, namely the Gerber standard, later CCIR System B, was promulgated by the CCIR in July, 1950.
But we know that Germany has 625 by 1948 (either because of AFN and the Americans tweaking 525 sets, or the two Germans "inventing" it in 1946) and the Russians using an 625 standard in Moscow at least by 1948 allegedly developed in 1944!

Certainly the Russians first used 8MHz Channels and it was later called the OIRT standard (later CCIR System D), if that is what they used in 1948. Europe used mix of 7MHz and 8MHz then and switched to 8MHz for UHF?

Early Belgian receivers were designed for four systems, namely B (Gerber), C (Belgian 625), E (French 819) and F (Belgian 819).
However Belgian 7MHz 819 line was a bit criminal


however Ireland was apparently the first user of the variant (CCIR-I no doubt) we have, which with colour is now called PAL-I

Interesting stuff here:
http://www.vintage-radio.net/forum/showthread.php?t=14741

http://www.vintage-radio.net/forum/showpost.php?p=105425&postcount=6

Table of CCIR here
http://www.ee.surrey.ac.uk/Contrib/WorldTV/broadcast.html


Interesting old site here http://stjarnhimlen.se/tv/tv.html with extract:

TV broadcast system parameters

Total    Active  Vertical      Aspect    Horizontal     Frate rate
lines    lines   resolution    ratio     resolution

525       484       242         4/3         427         30 or 29.94
625       575       290         4/3         425            25


Sys-  Lines Frames Lines Ch bw Vid bw Vid-Aud   Vestig Video    Color      Sound    Country/
tem           /s     /s   MHz   MHz   sep, MHz  sb MHz  mod      MHz     mod  swing organization
                                                                               kHz

(A)    405    25   10125   5    3       -3.5     0.75  C3Fpos     --     A3E   --   England
 B     625    25   15625   7    5       +5.5     0.75  C3Fneg  4.433618  F3E   50   EBU
(C)    625    25   15625   7    5       +5.5     0.75  C3Fpos     --     A3E   --   Belgium
 D     625    25   15625   8    6       +6.5     0.75  C3Fneg  4.433618  F3E   50   Soviet Union
(E)    819    25   20475  14   10     +-11.15    2     C3Fpos   (8.37)   A3E   --   France
(F)    819    25   20475   7    5       +5.5     0.75  C3Fpos            A3E   --   
 G     625    25   15625   8    5       +5.5     0.75  C3Fneg  4.433618  F3E   50   EBU
 H     625    25   15625   8    5       +5.5     1.25  C3Fneg  4.433618  F3E   50   Belgium
 I     625    25   15625   8    5.5     +5.996   1.25  C3Fneg  4.433618  F3E   50   England
 K     625    25   15625   8    6       +6.5     0.75  C3Fneg    4.3     F3E   50   Soviet Union
(K')   625    25   15625   8    6       +6.5     1.25  C3Fneg    4.3     F3E   50   
 L     625    25   15625   8    6       +6.5     1.25  C3Fpos    4.3     A3E   --   France
M/b&w  525    30   15750   6    4.2     +4.5     0.75  C3Fneg     --     F3E   25   USA/Japan
M/NTSC 525   29.97 15734   6    4.2     +4.5     0.75  C3Fneg  3.579545  F3E   25   USA/Japan
M/PAL  525   29.97 15734   6    4.2     +4.5     0.75  C3Fneg  3.575611  F3E   25   Brazil
 N     625    25   15625   6    4.2     +4.5     0.75  C3Fneg  3.582056  F3E   25   Argentina


System   Band   Video     Colour    Video   Audio       Band    Band
         lower  lower   freq  lvl   upper   freq lvl    upper   width

M,N     -1.25   -0.75   3.58  -7    4.2     4.5  -7     4.75    6.0

B       -1.25   -0.75   4.43 -16    5.0     5.5 -10     5.75    7.0

L       -1.25   -0.75   4.43 -16    6.0     6.5 -10     6.75    8.0

G       -1.25   -0.75   4.43 -16    5.0     5.5 -13     6.75    8.0
 dual sound                                 5.74 -20


Colour TV standard parameters


System            NTSC      ----------------------- PAL -------------------------       SECAM
CCIR               M           B,G,H          I            M            N            B,D,G,H,K,L

Luminance    ----------------------------- Y = 0.299 R + 0.587 G + 0.114 B -----------------------
signal

Chrominance  I=-0.27(B-Y)   ------------------- U=0.493(B-Y) ---------------------   D(B)=1.505(B-Y)
               +0.74(R-Y)   ------------------- V=0.877(R-Y) ---------------------   D(R)=-1.902(R-Y)
signals      Q=+0.41(B-Y)
               +0.48(R-Y)

Colour
subcarrier

Modulation   ------------------ QAM - Quadrature Amplitude Modulation ------------        FM

Frequency     3.579545 MHz   4.43361875   4.43361875   3.57561149   3.58205625 MHz   f(B)=4.25000 MHz
                 +-10 Hz        +-5 Hz      +-5 Hz       +-10 Hz       +-10 Hz       f(R)=4.40625 MHz
                                                                                         +- 2 kHz

Colour burst      min 8        10 +- 1      10 +- 1       9 +- 1       9 +- 1             none
duration
(periods)



Systems A, C, E, F and K' are obsolete and no longer used. These obsolete systems were used in:
A: England, Ireland: discontinued in 1986.
C: Belgium
E: France, Monaco: discontinued in 1986
F:
K': French overseas territories

lawhec

The last analogue TV variant (which is still used) is not mentioned in Watty's last post is I1 or PAL I1, used in territories using PAL I alongside digital broadcasts. The only difference to PAL I is that the vestigal sideband is 0.75MHz wide as opposed to 1.25MHz. It was introduced in the UK to reduce "breakthrough" to DTT multiplexes that were being transmitted on a lower frequency adjacent channel to current analogue broadcasts.

watty

Actually modern syncronous detectors could work with no sideband. Also in theory you could use the FM audio carrier to lock an SSB Video signal, thus no video carrier.

I wonder does UPC's ex Chorus use reduced sideband? They have Digital & analogue channels alternated.

Thanks for that snippet.

The 2.4GHz video senders are essentially the same FM video format with multiple FM audio subcarriers modulating the same FM video carrier as I was familar with in the 1970s for TV Microwave links. And also similar to Analogue Satellite, also FM.

Mike 1972

What are the arguments for using a 1.25 MHz vestigal sideband rather than (the apparently more efficent) 0.75 MHz ?

It was introduced in the UK to reduce "breakthrough" to DTT multiplexes that were being transmitted on a lower frequency adjacent channel to current analogue broadcasts.

Also to/from some analouge services (Channel 5 RSL's and existing services on channels adjacent to these)

watty

Historically a diode detector was used for video AM modulation. The more unsymmetrical it is the poorer a diode AM detector works. Modern receivers (since Mid 1970s possibly) use a PLL/Syncronous detector, so could even use no sideband. If you have no carrier you save power but then receiver is complex, current receivers need a carrier.

http://en.wikipedia.org/wiki/Vestigial_sideband

The engineering compromise is vestigial sideband modulation. In vestigial sideband the full upper sideband of bandwidth W2 = 4 MHz (USA) is transmitted, but only W1 = 1.25 MHz of the lower sideband is transmitted, along with a carrier. This effectively makes the system AM at low modulation frequencies and SSB at high modulation frequencies. The absence of the lower sideband components at high frequencies must be compensated for, and this is done by the RF and IF filters.

Mike 1972

watty wrote: »

Historically a diode detector was used for video AM modulation. The more unsymmetrical it is the poorer a diode AM detector works.http://en.wikipedia.org/wiki/Vestigial_sideband

What exactly are the consequences of this in terms of picture quality.

The wikipedia bit on VSB isint very detailed and is rather NTSC centric

Digifriendly

Mike 1972 wrote: »

How long before (BTW it was 1964 when 625 started 1967 was the date for commencment of regular colour broadcasts although there had been tests since the mid-late fifties)

625 line BBC2 did not come to NI until 1967 although it had begun in London area in 1964. See - http://www.tvhistory.btinternet.co.uk/html/ni.html Does anyone know when 625 line sets first went on sale in NI? Our very first set (bought in 1969) was one such 625 only set. Unfortunately we moved from Belfast to Larne 4 years later and BBC2 was the only channel we could receive as the 625 line transmitter in Larne did not carry the other channels at that time so we had to buy a second hand dual standard set to get BBC1 and UTV! We didn't get a colour set until we moved to Antrim town in 1978 (perfect reception from Divis then) and to complete things we moved to Glastry (Ards Peninsula, Co. Down) in 1982 and were able to pick up RTE1/2 (from recently opened Clermont Carn transmitter) as well as BBC Scotland (from Cambret Hill only on a very good high pressure day though!)

watty

Ermmm.
I remember having lecture on this in BBC Woodnorton.. But I can't remember ANY details..

If you didn't have enough lower side band, the more detailed parts of picture would be modulated by changes on the less detailed. I think you would have "ghosting" and flicker of more sharply detailed areas of picture by the change in lower detail parts (with an AM diode detector).

A synchronous detector "locks" a VCO onto the carrier (at 90 degrees) via a mixer and a 90 degree shifted version of the oscillator is mixed (2nd mixer) with the IF to generate the video. Then the amount of sideband doesn't matter if the Transmit frequecny response is tailor so response is what it would be if the original amount of lower sideband was there.

In the early days of 625, the IF strips had multiple transistor amplifiers and IF transformers as filters and you needed a Wobbulator with a assymetric response and scope to align the IF strip. The single IC amp + SAW filter then came in and the SAW filter had flat response above extend of vistigial sideband and sloped response across the carrier to compensate for extra amplitude combining the two side bands in the mixer as the frequency got toward 50Hz (virtually no energy apart from carrier within 50Hz).

Anyway the testcard could have much brighter horizontal than vertical grid due to poor response, wierd effects on the frequency grids.. smearing of the letter box, echo of white bar, terrible grey scale. All apart from any IF misalignment to do with Vistigial Sideband!

Part of reason RF of Modulator of SkyBox or VHS is poor and causes interference is that it's pretty near full AM. No vestigial sideband, but nearly all there. The older modulators even had a second copy of audio at -6MHz so with many older TVs you could tune in the audio carrier as video carrier and have sound buzz from video and an inverted spectrum, perhaps even a negative picture.

If I have time I'll take a picture of Sky Digibox Modulator spectrum and off air RTE so you can see.

watty

Digifriendly wrote: »

625 line BBC2 did not come to NI until 1967 although it had begun in London area in 1964. See - http://www.tvhistory.btinternet.co.uk/html/ni.html Does anyone know when 625 line sets first went on sale in NI? Our very first set (bought in 1969) was one such 625 only set. Unfortunately we moved from Belfast to Larne 4 years later and BBC2 was the only channel we could recieve as the 625 line transmitter in Larne did not carry the other channels at that time so we had to buy a second hand dual standard set to get BBC1 and UTV!

Thinking about it, since the TV was probably rented from a Nationwide chain, it's no surprise just North of Belfast we had a set with nothing on the UHF for ages.

I have a strong belief that even off Divis UTV and BBC1 was only on 405 for a while after BBC 2 started. The regular Clunk/Crack is burnt into my brain!

We moved Northwards too in late 1960s, but still got Divis. After I left home my mum moved to IslandMagee and got Sky Analogue early. Her receiver didn't get c5, I discovered she only realised it existed after she got Sky Digital. Early on she got TV from Scotland and then later there was a local relay. My Brother lives across the Lough from Larne. (I have photo someplace of him driving a capri across from Millbay, but that's another story)

Digifriendly

watty wrote: »

Thinking about it, since the TV was probably rented from a Nationwide chain, it's no surprise just North of Belfast we had a set with nothing on the UHF for ages.

I have a strong belief that even off Divis UTV and BBC1 was only on 405 for a while after BBC 2 started. The regular Clunk/Crack is burnt into my brain!

This link here - http://www.bookrags.com/wiki/UTV -(scroll down page to 1970's) says UHF 625 line UTV started from Divis in September 1970. What about BBC 1 625 line? I can remember watching Wimbledon on our 625 line set in 1969 (must have been BBC 2 only) and other channels mustn't have come on air but certainly can't remember not receiving BBC1/UTV and definitely remember watching 1970 FA Cup final on that TV on BBC1!

watty

OK so BBC2 in 1967 and UTV on 14th of September 1970. That makes sense and explains why we used the 405line AFTER BBC2 started

http://tx.mb21.co.uk/info/625/index.shtml

he first group of high-power stations so far planned is shown below; each station has been assigned four channels, one for BBC-2 and the others for possible future services. The BBC-2 Channel is shown in heavy type.

BBC2 was on its own at the start of 625 lines.

Divis however became the UHF main station for Belfast and surrounding area with BBC2 the first regular service commencing 18 March 1967. Colour UHF transmitters for BBC1 and ITV came into operation in September 1970.

http://en.wikipedia.org/wiki/Divis

When did C4 start on Divis? After nov 1982 I think


http://www.irish-tv.com/405.asp
(our very own Richard Logue )

Digifriendly

watty wrote: »

OK so BBC2 in 1967 and UTV on 14th of September 1970. That makes sense and explains why we used the 405line AFTER BBC2 started

http://tx.mb21.co.uk/info/625/index.shtml


BBC2 was on its own at the start of 625 lines.


http://en.wikipedia.org/wiki/Divis

When did C4 start on Divis? After nov 1982 I think


http://www.irish-tv.com/405.asp
(our very own Richard Logue )

Thanks for info but still confused over BBC1 625 line. Did it not start until Sept. 1970 from Divis? If so how can I remember definitely watching 1970 FA Cup Final (as well as 1970 World Cup) from BBC1 on a single standard set 625 line? Any help on this would be appreciated.
As regards C4 can clearly remember the opening of the station in early Nov. 1982 from Divis along with most of the rest of the UK. See - http://www.tvhistory.btinternet.co.uk/html/landmark.html (scroll down to 1980's).

SRB

The first set I remember in our house (Belfast, 1969) was duel standard and I remember using the "big clunky button" (or rather remember trying to reach it) to watch BBC1, so Watty, you must be right in that while BBC2 was up and running the others were still 405.
Ch 4, or rather the IBA testcard appeared in NI early in 1982. Wiped out our BBC1 Scotland - I seem to remember my Dad wasn't best pleased, though a new mast and Group B got him Cambret Hill.

Digifriendly

SRB wrote: »

The first set I remember in our house (Belfast, 1969) was duel standard and I remember using the "big clunky button" (or rather remember trying to reach it) to watch BBC1, so Watty, you must be right in that while BBC2 was up and running the others were still 405.

Do you not mean 405 line?


[he did. Fixed (mod edit)]

SRB

opps you got in before my edit, yup 405 !

Digifriendly

Still haven't found any definite link to when BBC1/UTV started 625 line transmission from Divis. If it was September 1970 this must have meant there were no B/W 625 line transmissions on these 2 channels before colour kicked in but both B/W 625 line and colour started simultaneously.

Elmo

Mike 1972 wrote: »

Incidently Id like to learn a bit more about the origins of System I but maybe thats one for the "History" board.

http://books.google.ie/books?id=gfeCXlElJTwC&printsec=frontcover&dq=brian+winston+media+technology+and+society&lr=#v=onepage&q=&f=false

Brian Wilson's Media and Technology is a good history of Telecommunications. IMO.

RTÉ had both from what I gathered in something I was reading recently. They had the UK system for those using it and also the European system. I must look that up again.


From Richard Logue:

And so it came to pass that an "Irish Solution to an Irish Problem" was adopted. Telefis Eireann would broadcast in 625 lines VHF across the country, however in the North and East of Ireland where BBC and ITV were available Telefis Eireann would also be available on 405 lines for those viewers who already had a 405 line set.

How did the cable companies work it?

watty

Cable was AFAIK only 625 and later.

Actually I remember reading Evesham carried 405 RTE.

Mike 1972

As far as I know the cable companies carried both 405 and (when available) 625 versions of all channels (except BBC2 which was 625 only) until at least the late seventies.

But maybe someone who actually lived in cableland at the time can confirm/correct this ?

watty

Ah, but WHICH cable land.

Mike 1972

Well given that most (all ?????) of the cable systems outside of Dublin date from 1980 or after I would say Dublin (of course it may have varied between the different companies operating within Dublin)

Elmo

Did many cable companies provide RTÉ on their service in the 1960s? Could you get RTE on cable in the north or did the north have many cable companies?

zilog_jones

http://en.wikipedia.org/wiki/Cable_television#United_Kingdom

Apparently cable systems in the UK were only legally allowed to transmit UK terrestrial channels up until 1984. Not what happened outside of the law though...

Cable TV in the UK is not very common at all compared to here, never mind in the '60s.

zilog_jones

zilog_jones wrote: »

http://en.wikipedia.org/wiki/Cable_television#United_Kingdom

Apparently cable systems in the UK were only legally allowed to transmit UK terrestrial channels up until 1984. Not what happened outside of the law though...

Cable TV in the UK is not very common at all compared to here, never mind in the '60s.

That's correct, Sky Channel was only made available in the UK in 1984, it had been in operation in parts of Europe since 1982 (not owned by News Corp) under the name of Satellite Television. Swindon Cable was one of the first to carry it.

Elmo

zilog_jones wrote: »

http://en.wikipedia.org/wiki/Cable_television#United_Kingdom

Apparently cable systems in the UK were only legally allowed to transmit UK terrestrial channels up until 1984. Not what happened outside of the law though...

Cable TV in the UK is not very common at all compared to here, never mind in the '60s.

Seems they called it piped TV over there also! I will let everyone know in the other forum. OTT

Back with the systems used.

Mike 1972

Elmo wrote: »

Could you get RTE on cable in the north or did the north have many cable companies?

Cable only came to Northern Ireland in the mid-late 1990's. Oficially Cabletel/NTL/Virgin hold the franchise for "Northern Ireland" (i.e. all of NI) in practice only parts of Belfast and L/Derry are cabled (Apparently the latter network is analouge only)

In Belfast RTE and TG4 (no TV3) are on digital cable (Channels 875/876 etc) but the picture seems to be sourced from analouge and horribly cropped.

I have never heard anyone in NI call it "piped" anything

zilog_jones wrote: »

Apparently cable systems in the UK were only legally allowed to transmit UK terrestrial channels up until 1984.

So what about the relays of RTE Watty (and others) have referred to ?

Elmo

Mike 1972 wrote: »

So what about the relays of RTE Watty (and others) have referred to ?

In ROI only areas with over the air access to BBC/ITV reception via NI and Britain were allow to have cable as it improved reception. Thats not to say that other areas didn't have some cable areas. About 40% of the pop could receive BBC/ITV before 1961 launch of RTÉ. This rule was introduced to allow RTÉ to develop with out competition in other areas. Don't know when the ban was removed. Hence all of the cable companies carried BBC 1, 2 and Channel 3 (UTV or TWW/TTW???). And why RTÉ TWO began broadcasting.

Which brings us nicely back to the point that RTÉ use the 405 and 625 lines in some areas. Have I got my lines right?

Mike 1972

Elmo wrote: »

Which brings us nicely back to the point that RTÉ use the 405 and 625 lines in some areas. Have I got my lines right?

Lines right but not grammer They used 405 and 625 but nowadays they only use 625 (oh and do some tests with some 1080 digiwhotsit)