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As to color accuracy - - - In the late 50's to early 60's, my grandparents had an RCA color TV. One of the "famous" movies either Brigadoon, South Pacific, or Oklahoma was to be shown on one of the networks. The network and each tv station to show it was "encouraged" to tweak things so that the picture quality and color accuracy was the best possible. Whatever they did worked quite well, and I've seldom seen comparable quality since. The cable companies seem to be more concerned about how many channels they can squeeze into things, at the expense of quality.

There were some tricks to the innards design of the old tube tv's. One I remember was a variable bandwidth IF. Seems that you could detect noise and signal strength, and narrow or widen the IF. This ultimately increased or decreased the higher frequencies in the video, producing less visible noise, or a "sharper" picture respectively.

In the latter 70's, we lived in the Eiffel area of Germany. PAL, SECAM, and even NSTC(Armed Forces) channels were present. Sanyo was selling a tv that had a large screen, and several smaller ones. It also had multiple tuners. You could display four channels on the various screens, and switch one to the larger screen. It automatically switched to the proper signal type. I thought that was a bit over the top, ($$$) and ended up getting a Sony that was mainly NSTC. If we wanted to really watch a PAL channel, it was in B/W only, and I had to use a small secondary PAL TV to listen to the sound.

Reply to
Charlie
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Ahem,. A time when one valve costmore than a whole IC subsystem on a chip..

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Reply to
The Natural Philosopher

Op Thu, 24 Dec 2015 16:08:39 +0000 schreef The Natural Philosopher:

Yes.

Sabena was a Belgian company.

groet Coos

Reply to
Coos Haak

That's still true today. It's just that the "valve" is a vanishing breed. Most of those still available are made in the old eastern block countries. (And I won't even talk about plumbers!)

>
Reply to
Charlie

This was purposely done to optimize the use of broadcast bandwidth. If you are viewing the (small to medium) screen from across the room, the human perceptual system mostly ignores the "coloring outside the lines" resulting from low chrominance bandwidth.

And in urban areas, the only time that multipath distortion was an issue was when an aircraft flew over at medium-low altitude.

Engineering is more about "good enough" than perfect, and color TV was an unqualified success in the US.

I do wish that we had chosen OFDM over QAM for digital transmission, but that's another story...

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Reply to
Michael J. Mahon

That was only on later BW TVs where the filtering had been adapted to the upcoming color standard. We had an old TV that pre-dated PAL color (ca 1962) and it still functioned when color was transmitted but the color subcarrier was clearly visible as a pattern, especially on the test card.

A wellknown problem too was the interference between a certain pattern in the BW picture that would generate a component close to the color subcarrier, e.g. a finely striped shirt or tie. This resulted in yellow/blue or red/green stripes in the picture on the classical TV sets.

My current set has digital demodulation and it does not show those effects, they have somehow been filtered out. Don't know how they achieved that, as AFAIK this problem was not a limitation of the analog demodulator but a limitation in the system itself.

(of course it rarely receives an analog color transmission today, it is still available on cable but no longer on the air or on satellite, so mostly only the external input from my DVB-T/C/S box is used which carries the signal as their separate components)

Reply to
Rob

Maybe it depends on the topology of the country, but in our flat country the multipath problem was not caused by aircraft but by tall buildings. (of course that resulted in static multipath and shadowing in the picture, we did not have any color issues as the local system here is PAL)

That is only because people's brains adapt very well to even the most awful picture. I have been to the US in those days (around 1990) and all I can say was that the TV picture was simply TERRIBLE compared to what we were used to in Europe.

This was not only because of NTSC vs PAL, but also because of the much lower resolution (both horizontally and vertically).

This also explains the early adoption of HDTV in the US and Japan. Even SD material, when taken up at the RGB or YPbPr level and then upscaled to HD would look much better, where in Europe the upscaled material did not look that much better than PAL. (there was a difference, of course, but not enough to make consumers rush to the shop for a HD TV)

Yes, another mistake. We have an OFDM Same Frequency Network here, and that works very well to give overal coverage for DVB-T with "window sill antenna" indoor coverage in built-up areas. Transmitters on the same channel are typically only 20km apart in urban areas here, transmitting about 10-20kW EIRP from tall buildings and low masts. Some transmitters at the original analog sites cover the large areas with about 50kW EIRP from a few hundred meters up.

Reply to
Rob

ISTR you live in The Netherlands, is your DTV received on VHF or UHF? Or both?

Reply to
mm0fmf

Only UHF here in the Netherlands. And everything is being moved to the lower half of the band, the upper half has been auctioned off for mobile data.

VHF band 3 is now allocated to DAB (only the top 2 channels in use), VHF band 1 is essentially vacant. Both bands are available for temporary licenses, defense, etc.

In the analog days we had 1 transmitter in band 1 (channel 4), and a couple in band 3, but UHF was most widely used.

Reply to
Rob

That reminds me of an argument I once had with a Canadian. He was quite sure that NTSC was far superior to PAL because their sets had a control for hew as well as saturation...

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Reply to
Graham.

Ah yes, the 'how far should we take an axe to the picture' control ...

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Reply to
The Natural Philosopher

Yeah. tell me about it, many's the time when a nasty winter high shoved

- Utrecht I think it was - bang into the middle of one of the UK channels...

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Reply to
The Natural Philosopher

I used to watch Dutch TV via sporadic E on Band I

Here in the UK, we made a quite brave decision not to re-engineer bands I/III for 625, and the 625 line services that would later become colour, only used UHF

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Reply to
Graham.

It thought the UK had moved all TV to UHF channels already in the analog days, by abandoning an old standard that was used only on VHF? If I'm correct, VHF band 3 was already used for mobile service in the UK for a long time...

Our band 1 transmitter was in IJsselstein near Utrecht, 100kW EIRP on channel 4. The same site had 1MW EIRP on UHF channels 27 and 30 for the 2nd and 3rd programme. All horizontally polarized.

In 2006 the analog transmitters have been shut down, the channel 4 antenna has been removed, and the UHF antenna has been replaced by a vertically polarized antenna which now transmits DVB-T on channels

24, 27, 49, 50 and 57. Only about 15kW EIRP from that site.

The antenna is about 370m high on a hybrid concrete/steel tube tower. In this season, the guy wires have lights on them to give it the appearance of a christmas tree.

Lately I am working there with the local amateur radio repeater club every week to move our repeater systems on that tower to a new location. They were located in a cabin halfway the steel mast and are now being moved to a floor in the concrete tower. repeaters active there are PI3UTR (2m FM), PI1UTR (70cm DMR/DSTAR), PI2NOS (70cm FM), PI6ATV (3cm ATV). There are also receivers for 70cm WebSDR (websdr.pi1utr.ampr.org) and for a 10m repeater PI6TEN. Four 19" racks full of equipment...

Picture of the tower (pre-2006) can be seen here:

formatting link
The large array of red antennas below the top are the channel 4 antenna, below that is a smaller array for FM broadcast. That has now also been removed and replaced by a new array mounted where the channel 4 antenna used to be, and vertically polarized instead of horizontal as before.

Reply to
Rob

Now we have the rubbish known as DAB in parts of Band III.

The signal on 220MHz does not propagate like 100MHz signals do for FM analog radio. This results in scabby and patchy reception in most of Scotland whereas FM is perfectly fine. When you can get a signal, the audio is transmitted with such low bit rates using crappy MP2 encoding that it sounds worse than the FM it is meant to replace.

Not a success. DVB-T does seem better in that there are quite a few high bit rate TV stations giving decent picture quality if not content.

Reply to
mm0fmf

In the UK? That probably was Tropo. Sporadic E reception of that transmitter would be more likely in e.g. Spain. (we regularly received a transmitter from Spain on channel 2 with ES)

That is what I mentioned in my other reply...

In the Netherlands, regular broadcast TV started as 625 lines B/W on VHF (band 1 and 3), in the fifties. Before that it was only experimental and probably some lower res standards were used, but never in the regular service.

In 1964, the 2nd programme started on UHF and in 1988 a 3rd programme was added on UHF as well. Some filler transmitters for the first programme were also on UHF.

However, the vast majority of viewers have been on cable since the eighties, with a minority using DVB-T and DVB-S and now an increasing number using IPtv over ADSL/VDSL and FTTH.

Reply to
Rob

"but UHF was most widely used." is what was said, and yes, there it was.

I don't read Dutch, so the occasional flickering images of Nederlands cannot be guaranteed to have emanated from a particular transmitter, but IIRC that was the one most in line of site of my local UHF transmitter.

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Reply to
The Natural Philosopher

I get 100+ channels of near rock solid reception quality (shame about the low bandwidth MUXES though) off a stock TV aerial pointing at te local free to air transmitter.

UK has mostly got DVB sorted out.

DAB is, I here, a flop, but I don't have it.

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Reply to
The Natural Philosopher

Here the DAB was scrapped before it was too widely being used, and replaced by DAB+. Still a bad decision, I think. I have no DAB+ radio so I cannot comment on the coverage, but new transmitters have been rolled out recently and it being a Same Frequency Network it should eventually get good coverage.

Indeed the quality is arguably less than analog FM. But of course you can receive the same radio content via DVB-T as well.

TV over DVB-T is now losing out to cable, satellite and IPtv because it does not offer HD. The current license (held by the incumbent telecom) ends in two years time, it is not clear what will happen then. My personal guess (and fear) is that it will be sold to some overambitious little company that will fail shortly after that, and it will be shut down.

Reply to
Rob

Unfortunately the testcards identifying the transmitter were shown only very infrequently. I remember in the seventies I did a lot of TV DX hunting with some friends after school, and when receiving testcards from Germany they all had the transmitter site name the entire afternoon. The Dutch testcard only showed "Nederland 1" or "Nederland 2" and was the same on all transmitters. There was a local testcard but it showed only for a few minutes before shutdown at night.

Of course today all channels run 24/7 without ever showing a testcard.

Reply to
Rob

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