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Television Standards Converters, Modulators etc Standards converters, modulators anything else for providing signals to vintage televisions.

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Old 27th Oct 2007, 11:49 pm   #1
DoctorWho
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Default When analogue and 625 are switched off what converter will we need?

The Aurora does a fantastic job supplying a superb 405 signal, but I was wondering what will happen when analogue and 625 are completely gone and we are then presented with what they now like to term "HD" only signals.

Will we then need some kind of converter to convert so-called "HD" to 625, and then feed that signal to the Aurora?

I can see a lot of us going to Darryl and asking him to please develop a similar converter to the Aurora to downscale "HD" to 625. The biggest problem I see though is that there is more than one "HD" system in use, so it would, to a degree, need to accept more than one standard as an input.

I see an interesting time ahead of us where there will be quite a jumble of VHS, DVD, BluRay, HD-DVD, Freeview, HD TV and so on, so there will be quite a number of different types of signal to deal with!

We lose analogue here in 2009, and whilst it's sad, it's not as sad to me as it was when 405 was switched off, all the same I shall miss it though. I've always said that television has never been the same since January 1985 anyway, and it's only now that we can obtain a superb 405 signal that I've any interest in watching again. There's something so relaxing about sitting for an evening with some archive footage and a 405 line set. Nothing like it!
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Old 28th Oct 2007, 12:26 am   #2
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Default Re: When analogue and 625 are switched off what converter will we need?

Depends. This PC (Toshiba) does actually generate 625 Lines! Some Freeview ones do too. Old Videos do. Some DVD players do too.

For about a fiver, you can get a set of leads to transfer Scart to Video + Audio. And also to convert S-Video to Composite.

Go to http://www.oldtellys.co.uk/otindex.html and read the section for BTHT Tests for details.

Cheers,

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Old 28th Oct 2007, 12:04 pm   #3
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Default Re: When analogue and 625 are switched off what converter will we need?

One of the problems with modern set top boxes ASAIK is they cannot be switched to come on to a particular channel after a power cut, (unlike sky boxes)

It may be an idea to use a number of sky receivers, with audio and video output going to encoders and modulators then feed the RF analogue through the aerial distribution system.
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Old 28th Oct 2007, 2:07 pm   #4
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Default Re: When analogue and 625 are switched off what converter will we need?

My guess is that getting 625-line signals will be no problem. I have a Humax HD receiver and it has a SCART output that produces a 625 signal simultaneously with the HD outputs. I imagine this will be the norm for HD devices for a long time.

Modulators however are likely to be a problem. The Motorola/Freescale chips that Darryl and I used in our standards converters will only be made as long as there are analogue TVs to be fed. It is perfectly possible to build a digital modulator into the FPGA design, the only reason I didn't do this is that at the moment the effort : benefit ratio is not favourable, plus it would need a much more expensive DAC chip.

At the other extreme, one could still build a good old fashioned discrete component modulator.
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Old 28th Oct 2007, 2:13 pm   #5
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Default Re: When analogue and 625 are switched off what converter will we need?

I've also been contemplating this lately as our switch-off is in Feb. 2009. I'm designing a replacement for the multi-standard converter now which will probably be my last analog input only converter. I would imagine that anything done in the future would be HD capable. That's not to say there won't be a need for the current analog input based converters, since there will be many ways to generate a standard PAL/NTSC signal for a long time to come.

While it is true there are many different resolutions in digital television, analog component YUV and digital HDMI are the main connection types. Theoretically a converter with these two inputs could support anything from composite PAL/NTSC and component PAL/NTSC to component HD and HDMI HD. Since most HD resolutions are higher than current analog PAL/NTSC, there would be plenty of information available.

The only real issue is cost. Since HD can contain up to 6 times as much information as PAL/NTSC, all the parts in the data processing path from the input, to the memory, to the fpga have to be much faster. Eventually, as with the current converter, parts will become available that will help drive this cost down. Unfortunately this may be sometime after the 2009 shutdown. Until then, it will probably be most cost effective to use converters with standard PAL/NTSC inputs and commercially available HD -> PAL/NTSC scalers. These are predicted to be very inexpensive at first due to the volume they will be made in for use with all the non-HD televisions currently in use.

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Old 28th Oct 2007, 2:16 pm   #6
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Default Re: When analogue and 625 are switched off what converter will we need?

David,
Good point about the modulators. I hadn't considered this one, but it makes sense that once the analog sets are gone, there will be no need for these chips. I guess we will have to revisit the alternatives.

Darryl
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Old 28th Oct 2007, 8:11 pm   #7
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Default Re: When analogue and 625 are switched off what converter will we need?

It will be interesting to see where things take us next. I can see that the next generation of converters will need to accept "HD" signals (I hate that term for 'new' standards since 405 is HD). What would be involved in designing a converter to accept both PAL/NTSC and the new "HD"?

Currently we have Freeview boxes here which receive the digital channels and fedd them via SCART or convert to analogue RF, but obviously these won't downscale "HD". Our shutdown of analogue is also due in 2009, so i would expect to see some such equipment made available.

What still amazes me is that TV sets and DVD recorders are still being made and sold with analogue only tuners!!
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Old 28th Oct 2007, 8:36 pm   #8
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Default Re: When analogue and 625 are switched off what converter will we need?

Quote:
Originally Posted by DoctorWho View Post
Currently we have Freeview boxes here which receive the digital channels and fedd them via SCART or convert to analogue RF, but obviously these won't downscale "HD". Our shutdown of analogue is also due in 2009, so i would expect to see some such equipment made available.
I suspect that standard definition (625 line) rather than HD will be the norm for terrestrial digital TV (Freeview) in the UK for some time after the analogue switch off. There appears to be no great enthusiasm among UK broadcasters, Ofcom and government to provide HD terrestrial digital TV services.

John
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Old 28th Oct 2007, 8:43 pm   #9
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Default Re: When analogue and 625 are switched off what converter will we need?

Lets hope you're right John. I've noticed that Sky are offering more and more "HD" channels, presmably requiring a new box to receive them, and so I wonder if these new boxes receive standard 625 as well as "HD".

Hopefully 625 will remain the norm for the foreseeable future, but with more and more programmes being shot on "HD" by the BBC and other companies you do begin to wonder.
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Old 29th Oct 2007, 9:38 am   #10
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Default Re: When analogue and 625 are switched off what converter will we need?

I presume that they wouldnt be geting evyone to get a set top box etc so that digital can be used after switchoff of analogue only for the set top boxes not to work at switchoff
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Old 13th Feb 2008, 2:49 am   #11
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Default Re: When analogue and 625 are switched off what converter will we need?

I don't think that we will need to worry to much about this for a few years ,but digital will increase on tv and radio but i am sure that the ingenius chaps who run older equipment will come up with something,neccesity is the mother of invention
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Old 13th Feb 2008, 6:59 pm   #12
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Default Re: When analogue and 625 are switched off what converter will we need?

It's worth noting that my PC/Linux/MythTV solution will continue to work as, regardless of the resolution of the received broadcasts, DVD/Blu-ray discs etc., the pictures will be scaled to whatever resolution has been configured for the display device.

Personally, I'm awaiting free-to-air HD broadcasts and cheaper HD-DVD/Blu-ray drives as I'll finally have a higher-resolution signal source to scale down for my 819-line set
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Old 6th May 2008, 3:39 am   #13
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Default Re: When analogue and 625 are switched off what converter will we need?

I didn't see anybody mention my old bodge for running certain video game consoles which only have composite video and audio outs into rf only tv's.

I have for a long time scavenged the rf modulators out of old (usually smashed) vcr's which seem to do nicely. They are mostly video/audio in and 12v with a nice adjustable chan 32-46 ish uhf output. Best devices I ever found for this job come from the Sony betamax top loading vcr's.. They even have the inputs labeled on the can The usual vcr sync bodges will be needed for certain sets, as has been well documented.

As the switchover is only to digital and not HD broadcasting I don't see a problem for at least the next 10 years or so. The cable companies and broadcasters are too cheapskate to go HD until they see that the majority have HD capable tv's.
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Old 6th May 2008, 7:19 pm   #14
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Default Re: When analogue and 625 are switched off what converter will we need?

I wonder how long cable companies will continue to provide an analogue signal! When I asked one of ntl's engineers (fairly recently) about this he said they had no intention of discontinuing analogue services in the foreseeable future, as there are still a large number of analogue boxes out there (and by the way I've fitted a CATV outlet in all but one room, I'll do the front room downstairs in due course).

Many modern TVs with VHF, or better still, hyperband tuners will receive a lot of the cable channels directly. I only have one cable box!



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Old 6th May 2008, 7:49 pm   #15
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Default Re: When analogue and 625 are switched off what converter will we need?

What about scrambling? I worked for Telewest and every channel was scrambled.

We might need another thread for this though.

Cheers,

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Old 8th May 2008, 10:10 pm   #16
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Default Re: When analogue and 625 are switched off what converter will we need?

Yes, maybe slightly OT - but the multiband/hyperband TVs receive a few channels which the cable box won't (except via subscription) and vice versa - the cable box decodes some scrambled channels on the basic sub. All they do is invert the sync. Far better quality than the old $/y VideoCrypt system, which gave poor quality results on scrambled channels. Many nt-hell channels are not encrypted

This is not really relevant for this thread though, I was pointing out the possible future availability of CATV signals as a source for our standards converters


If anyone's interested in a thread discussing the merits of various scrambling systems I'm up for it, though I am wary of drawing unwanted attention


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