240, 405, 625, 1080… GO! 

31 December 2022 tbs.pm/77313

Ten years ago we were coming to the climax of the great Digital Switchover as the last of the analogue television transmitters were switched off. A system of broadcasting since 1936 (albeit to a 1960s standard) was disappearing forever, something that the TV industry – broadcasters and manufacturers – had been preparing us for since the start of the new millennium. During the lead up to the changes, as one who embraced the new technology, I was frequently hearing moans and complaints from many who objected to the possibility that their TV set could become obsolete overnight. I had to reassure them that this was unlikely to happen, it would take a little time and that in any case, by the time it did happen they would probably have the right hardware for it.

But it took a lot of convincing for some, many of those getting worried had been born in the early 1970s, they’d never experienced an upgrade in TV broadcasting, so I had to explain to them that this was actually nothing new, the broadcast technology they had grown up with was the most recent in a long line of technical developments and if, like me, you were around in the era before colour television, you will recall that as far as simply buying a TV was concerned, nothing really stayed still for long and no consumer technology would ever be futureproof.

Being purely hypothetical here, let’s assume that you’re living in London and you’ve been a TV technophile since the day of the first public broadcast on 2nd November 1936. The chimney stack on your house has been burdened with a huge ‘H’ shaped antenna, able to receive the BBC transmissions from Alexandra Palace on Channel 1 in VHF Band 1 to which your TV set is permanently tuned, there being no need for it to find any alternative frequencies. The set will have been built to a dual standard, able to receive both the Baird 240 line system along with the Marconi 405 line service which are jointly being heralded as ‘The World’s First High Definition Television Service’. You’ll get the chance to use both on the first day, as after the first hour on 240 lines the BBC will re-stage the entire broadcast on 405 lines, therefore it’s interesting to note at this point that even the first afternoon of BBC Television includes repeats, also interesting to note that at this point the BBC are also unknowingly providing the first “…+1” service!

Within three months though a good deal of circuitry in your set has become redundant as in January 1937 the BBC drop Baird’s 240 lines and settle on the Marconi 405 line system, a standard that would remain in place until 1985 although it would become outdated a lot sooner. There is of course the interruption to the service between 1939 and 1946, but when the transmissions resume there’s little to suggest that any major changes are on the table. When the BBC expands the service with their second transmitter at Sutton Coldfield in 1949, sets sold in the area are known as ‘Birmingham’ versions, permanently tuned to Channel 4, again in VHF Band 1. This won’t really bother you unless you move, meaning an engineer will have to make alterations to your set (if your set is compatible with such alterations), or you’re living in an ‘overlap’ area able to receive both signals, in which case your television dealer will happily advise you of the best option. It won’t be until 1950 when the Bush TV22 becomes the first receiver to enable viewers to manually tune across all five available channels in Band 1.

Fast forward now to 1954 and you’re getting all excited about the government giving the go-ahead to the new service from the Independent Television Authority (ITA) due to start in September next year. Over the coming months however you notice there’s a slight catch in that the new service will be transmitted in the higher frequency range of VHF Band 3, in London this will be on Channel 9. For your existing Band 1 TV set there’s the option of a Converter Box (or as we would know it today, a Set Top Box) capable of converting the Band 3 signal down to the local BBC Band 1 frequency, which works fine until the set picks up enough stray BBC signal to cause patterning on the ITV picture. Many of the last ‘Band 1 only’ receivers have indeed been designed with the coming of ITV in mind and are able to incorporate new Band 3 tuners at a later date (these are marketed as ‘ITA Ready’ or ‘Band 3 Ready’ sets), useful being that it will take around seven years for the ITV network to become established in all of its fourteen regions. The obvious and best route though is a new fully compatible Band 1/Band 3 set, but all of these options require a new Band 3 aerial, albeit slightly smaller than your existing Band 1 set up, pointing at a different transmitting station. For reasons either technical or political (or maybe both) the ITA have been denied the use of the BBC sites and are having to set up their own transmitter network, leading to the visual presence of two TV masts in close proximity at certain locations, for example Crystal Palace (BBC) and Croydon (ITA) in London or Sutton Coldfield (BBC) and Lichfield (ITA) in the Midlands.

Less than nine years after the launch of ITV you’re hearing rumblings about yet another technical development looming fast on the horizon, requiring another ‘upgrade’ as we would refer to it nowadays. It’s because of these ‘upgrades’ and the slow realisation that nothing is going to stand still for long in the TV world that many have chosen to rent their sets rather than buy outright, although a more common reason being the sheer expense of fixing and maintaining what is still seen as a new and rapidly developing piece of home technology.

Of course it’s the coming of Britain’s third TV channel that’s the cause of these upgrades. BBC2 will be transmitting in the new UHF band on Channel 33 in London, requiring yet another (though much smaller) aerial clinging to the chimney stack. It’s also being broadcast using the new higher definition 625 line system, so a set top box converting the higher channel frequencies is out of the question, a new set being essential, one which is also dual standard in order to receive BBC1 and ITV on VHF Bands 1 and 3 in 405 lines. Again, with the gradual roll out of BBC2 set manufacturers are able to supply ‘BBC2 Ready’ receivers with the built in provision for a new tuner and 625 line circuitry to be fitted at a later date, but they’re not quite as satisfactory as a fully kitted out dual standard set which of course is what you’ve shelled out for. There’s not actually much to watch on the new channel, but at least when there is it will look stunning!

Incidentally, while all this has been going on you’ve added another aerial to your rooftop collection (horizontally polarised for VHF Band 2 this time) because let’s face it, you’ve also been kitting yourself out with the latest High Fidelity sound equipment and you’re eager to try out the new stereophonic radio transmissions being put out on the BBC Third Programme on their FM service.

But back to the TV and, as we’ve worked out, things really aren’t standing still for long in the rapidly moving world of technology as you discover three years later (Saturday 1st July 1967 to be precise) while walking past your local ‘Radio Rentals’ and you catch a glimpse of Europe’s first official public television transmission in colour. A twenty-five inch screen in a huge wooden cabinet has drawn your attention to that afternoon’s tennis from Wimbledon and of course this is your next investment. The good news here is that it works perfectly with the aerial you had installed for BBC2 three years ago and thankfully, being a dual standard set it also works with VHF Band 1 and Band 3 aerials, which is just as well as it’s only BBC2 that’s actually broadcasting in colour and at this point maybe only one programme each day. It won’t be until December that the full colour service will begin and even after that you’ll still be watching a lot of your favourite BBC1 and ITV programmes in good old 405 line black and white.

The coming of colour to BBC2 brings even better news because around this time the powers-that-be have decided that, from 1969 onwards, 625 line UHF will become the universal standard for all television broadcasting in the UK when BBC1 and ITV launch their colour services from November that year. Some joined-up thinking leads to all three services being broadcast from the same transmitting stations meaning that your existing BBC2 aerial will happily receive them all. Of course your dual standard set will still work as the 405 line services will be there for some time to come, but really, after the coming of UHF and colour on all channels, there’s little or no need to tune in to VHF Channels 1 or 9 ever again. TV manufacturers can now concentrate on producing single standard sets again, the black and white models often capable of displaying a 625 line picture of far better quality than their dual standard predecessors.

This brings us to a somewhat unusual prolonged state of stability in television broadcasting. With no new dynamic developments on the horizon the manufacturers have turned their attention to different ways we can play with our TV sets, notably by recording our favourite programmes to watch at our convenience, “taping” them while we’re out or even when we’re watching another channel. Between them Philips, JVC and Sony are offering recorders using totally incompatible systems and unable to play each other’s tapes. At the same time other manufacturers have developed little boxes that allow you to play games on your TV screen and these, like the Video Cassette Recorders, feed their output into your set on a UHF frequency never used by the broadcasters, usually Channel 37 (best make note of that number…..).

It hasn’t been all quiet on the broadcasting front though. Every UHF TV set that you’ve come across has had at least four channel buttons, but has only been able to receive three and you’re dying to press that fourth one and actually see a picture. Ever since the arrival of BBC2 in 1964 there’s been talk of an “ITV2” although it’s never actually been promised. Throughout the ‘seventies successive governments and broadcasting committees have been arguing about the feasibility of a fourth channel and who should run it, but at the start of the ‘eighties the decision is taken that from 1982 the UK will have a fourth television service.

Even better news is that with the standardisation back in the ‘sixties that enabled the three existing TV services to broadcast on 625 line UHF, the same joined-up thinking has allocated space for a fourth channel from each transmitter should it ever be needed. For the first time the arrival of a new channel won’t require a new TV or a new aerial; Channel 4 will be available simply by tuning in the fourth button on your set. You’ll probably treat yourself to a new set seven years later though when ITV and Channel 4 (along with the BBC shortly afterwards) start adding NICAM digital stereo sound to their transmissions, you’ll also need a new VCR too as you won’t want to record those programmes in mono!

From this point things start to take a rather familiar turn and you begin to feel like you’ve been here before. At the end of the ‘eighties a new broadcaster by the name of SKY is offering a package of multiple channels beamed direct to your house from a satellite, so your stack of aerials is now joined by a rather large dish attached to the side of your house. The channels are broadcast at a frequency way above anything your TV set can receive, so a set top box is needed to bring them back to terrestrial wavelengths (reminiscent of the ITV set top converters in the ‘fifties). Then towards the end of the next decade there’s talk about increasing the amount of channels by transmitting them as digital signals. No one’s making sets capable of receiving these digital broadcasts yet, so the manufacturers are marketing new sets as ‘Digital Ready’, just like those ‘ITA Ready’ and ‘BBC2 Ready’ sets in the ‘fifties and ‘sixties respectively, the difference here being they can only be used to watch digital broadcasts via a set top (converter) box, some of which are designed for the new digital service from that SKY channel; yes, you’re already replacing that satellite set-up you kitted yourself out with less than ten years ago. Furthermore, they’ve changed the shape of the TV picture, to get full advantage of the new digital broadcasts (when they come) you will need one of those new Widescreen sets; it will be worth it in the long run. By the time you’ve done all of this they will have started making sets able to receive both digital and analogue signals (Dual Standard, just like those Baird 240 line/Marconi 405 line sets in the ‘thirties and the VHF/UHF sets in the ‘sixties).

While all of this has been brewing up something rather strange has happened, somehow a fifth TV channel has been shoe-horned into a network designed for four. It’s broadcasting on UHF Channel 37, the same one your video recorder uses to feed pictures to your TV, so a technician has to call at your house to alter the output of your VCR so you can watch the new Channel 5 interference free…… except it’s not quite that simple. You’re getting all of your traditional four channels from the transmitter at Crystal Palace, but Channel 5 is coming to you from a mast at Croydon, just slightly to the side of where your aerial is pointing and for this reason the picture will always look slightly wrong.

Never mind, that new digital stuff is just around the corner, so this is probably as good a time as any to leave our trip through TV upgrades and switchovers. Not long after this you’ll be enticed by new High Definition (HD) services being broadcast in a stunning 1080 lines, bearing in mind that the original 240/405 line transmissions were billed as ‘High Definition’. Again at this stage, no sets will actually be available that are able to receive the signals but they will be marked as ‘HD Ready’, needing to be fed again by set top (converter) boxes.

As I said earlier, you feel like you’ve been here before.