405 Line Stuff - Almost unique to the UK.

Anything not specifically related to NBTV, but at least of some technical nature that might be of interest to NBTV members. Items for sale and links to retailers do not belong here.

Moderators: Dave Moll, Steve Anderson

405 Line Stuff - Almost unique to the UK.

Postby Steve Anderson » Thu Apr 21, 2022 8:24 pm

I live in a country that has never been served by 405-line TV, basically it appears to be a uniquely British standard, though there were some cable networks running it in Hong Kong for a while. When? No idea.

This is a specialised interest, but historically it should not be neglected. There seems to be plenty of content 'out there' on 405 so go fill your boots...

So, you're fortunate enough(?) to live in the UK and get your hands on a 405-line TV. Now what? There's been no 405-line TV transmitted since January 1985 for the majority of the UK.

However there are sources available that produce 405 signals, but as ever, I wanted to do it myself. My initial guidance was here...

http://www.thevalvepage.com/projects/te ... stcard.htm

...but things have moved on since then...so here (might be) an updated version...I need the check with the original designer if it's OK to go ahead as I'll be using his video data.

Steve A.
User avatar
Steve Anderson
"Fester! Don't do that to 'Thing'"
 
Posts: 5360
Joined: Fri Mar 30, 2007 10:54 pm
Location: Bangkok, Thailand

Re: 405 Line Stuff - Almost unique to the UK.

Postby Viewmaster » Fri Apr 22, 2022 3:17 am

There are advanced plans and equipment built to start broadcasting 405
again.
https://405-line.tv/
“One small step for a man,"......because he has Arthritis.
Albert.
User avatar
Viewmaster
Frankenstein was my uncle.
 
Posts: 1306
Joined: Fri Apr 06, 2007 4:50 am
Location: UK Midlands

Re: 405 Line Stuff - Almost unique to the UK.

Postby Dave Moll » Fri Apr 22, 2022 7:36 pm

Steve Anderson wrote:So, you're fortunate enough(?) to live in the UK and get your hands on a 405-line TV. Now what? There's been no 405-line TV transmitted since January 1985 for the majority of the UK.

However there are sources available that produce 405 signals, but as ever, I wanted to do it myself. My initial guidance was here...

http://www.thevalvepage.com/projects/te ... stcard.htm

...but things have moved on since then...so here (might be) an updated version...I need the check with the original designer if it's OK to go ahead as I'll be using his video data.

Steve A.


There have been a number of standards converters produced over the years, including vast valve-based units used by the broadcasting outfits themselves during the dual-standard era, but I know of the following (in roughly chronological order) produced within the vintage television fraternity:

Pineapple
Dinosaur (like the Pinapple before it and the Domino after it, this is now extinct)
Domino (I have one of these, bought at great expense some years ago when I was actively playing with 405-line television)
Aurora (currently out of production)
Hedghog (currently being produced - and this is the correct spelling)

I know there have been others, but I don't know details.
User avatar
Dave Moll
Anyone have a spare straightjacket?
 
Posts: 460
Joined: Tue Feb 27, 2007 9:11 am

Re: 405 Line Stuff - Almost unique to the UK.

Postby Steve Anderson » Fri Apr 22, 2022 10:24 pm

Well, it depends if you just want a simple Test-card source (as per my link) or a full live standards converter. The two are very different. The test card source is comparatively easy, the standards converter, whether 405-625 or the other way around, not so. Ask those that have done it before...

But it begs the question (putting on my commercial hat for a moment) how many 625 (or whatever) to 405 converters could you sell in a year, or even in total? Here in 2022 I would think less than 10. Simply not a viable proposition. You could do it for the love of it, but there is a limit.

Steve A.
User avatar
Steve Anderson
"Fester! Don't do that to 'Thing'"
 
Posts: 5360
Joined: Fri Mar 30, 2007 10:54 pm
Location: Bangkok, Thailand

Re: 405 Line Stuff - Almost unique to the UK.

Postby Dave Moll » Sat Apr 23, 2022 5:51 pm

As to how many Hedghogs have sold, one would need to ask Frank C and Freya on the Vintage Radio Repair and Restoration Forum, who between them designed and build the item.

As you say, a simple test card generator is a lot less challenging.
User avatar
Dave Moll
Anyone have a spare straightjacket?
 
Posts: 460
Joined: Tue Feb 27, 2007 9:11 am

Re: 405 Line Stuff - Almost unique to the UK.

Postby Harry Dalek » Sat Apr 23, 2022 11:16 pm

Hats off to some one trying it brain storming the idea.
405 line video signal easiest way i could see is would be a grey scale stair case generator and add the syncs
Still you need a Monitor
R (4).jpg
R (4).jpg (12.53 KiB) Viewed 6262 times

Now if you work backwards and have a monitor first you can make a flying spot camera or slide camera still you need another monitor to view .
Another way a 625 line camera converted down to it or one from scratch.
Can an old 625 line VCR record 405 ? even if so a little out dated and a bit pricy these days shipping tapes if some one can record it for you .
Then you go to system converters a few of those about over the years
viewtopic.php?f=8&t=3024
viewtopic.php?f=8&t=3014

Or perhaps the easiest multi system system converter via a PC graphics video card desktop PC
Please view the video in the linked post below its pretty simple !
download the mode line program and see if your current card will work or what it can do ? http://www.geocities.ws/podernixie/htpc ... ne-en.html
I only played around with what my card could do but with the right card the problem is solved ,i think this is the best way to go /
viewtopic.php?f=8&t=2548
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 5364
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Re: 405 Line Stuff - Almost unique to the UK.

Postby Steve Anderson » Sun Apr 24, 2022 3:20 pm

Yes generally a VHS VCR (and probably Beta too) will record and playback the old UK 405 standard OK. The 625 and 405 systems both used 50Hz for the the field rate, .i.e 25 frames/sec. The exception would be if the VCR had a timebase corrector, that would need to be switched into bypass. But few machines had that, and those that did were very expensive.

It's a similar concept to the first (that I'm aware of) domestic digital audio recorders that used standard VHS/Beta tapes, made by Sony and encoded the audio into a pseudo-TV waveform. If you viewed the video on a monitor or TV (the encoded audio stream) it looked like a 'rolling barcode'.

I did an item based on the same concept for NBTV. It did appear in the newsletter...which one? No clue! My first attempt at a DC-friendly recording medium...

Steve A.

I also sent the item to the BATC, they published it in their CQTV magazine...

Re-reading that item well over a decade later (almost two), I would do it a lot different now!
Attachments
Proof 2.pdf
(1.68 MiB) Downloaded 119 times
User avatar
Steve Anderson
"Fester! Don't do that to 'Thing'"
 
Posts: 5360
Joined: Fri Mar 30, 2007 10:54 pm
Location: Bangkok, Thailand

Re: 405 Line Stuff - Almost unique to the UK.

Postby Harry Dalek » Sun Apr 24, 2022 4:49 pm

Steve Anderson wrote:Yes generally a VHS VCR (and probably Beta too) will record and playback the old UK 405 standard OK. The 625 and 405 systems both used 50Hz for the the field rate, .i.e 25 frames/sec. The exception would be if the VCR had a timebase corrector, that would need to be switched into bypass. But few machines had that, and those that did were very expensive.

It's a similar concept to the first (that I'm aware of) domestic digital audio recorders that used standard VHS/Beta tapes, made by Sony and encoded the audio into a pseudo-TV waveform. If you viewed the video on a monitor or TV (the encoded audio stream) it looked like a 'rolling barcode'.

I did an item based on the same concept for NBTV. It did appear in the newsletter...which one? No clue! My first attempt at a DC-friendly recoding medium...

Steve A.


I think i recall you mentioning it to me some time back one easy way to have the signal apart from postal costs and tracking some one down to record it and post it .
I still have a number of VCRs to play with 2 Super VHS machines ,the last generation of video recorders were HD recorders always wondered if they could do it .
Volume 31 Number 1

[3-8] Using a Domestic VCR to Record NBTV Video by Steve Anderson steveand@samart.co.th

You are in this issue but you did do a lot with VCRS i noticed in the newsletters doing a search .

BTW on the video card systems converter you and not limited to 405 line but can punch in others such as Bairds 240 line or what ever very useful for a monitor and pretty cheap for a multi system systems converter ,i only have a desk top in my shed i would like a smaller desk top for the video card that can do this ,not something the size of a refrigerator :lol:
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 5364
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Re: 405 Line Stuff - Almost unique to the UK.

Postby Steve Anderson » Sun Apr 24, 2022 5:18 pm

That e-mail (the Samart one) is well and truly dead now, perhaps around the time the article was published...use the PM function here or my e-mail address on the NBTVA website.

Basically if the video system has an element of 50Hz in the video waveform, then an analogue VCR should record it. There are 'get arounds' for those NBTV systems running a 25/12.5Hz frame-rate too, which are quite simple.

Steve A.

I should have said, "Any European VCR", Unless a US (or other 60Hz machine) is multi standard, it probably wont work...
User avatar
Steve Anderson
"Fester! Don't do that to 'Thing'"
 
Posts: 5360
Joined: Fri Mar 30, 2007 10:54 pm
Location: Bangkok, Thailand

Re: 405 Line Stuff - Almost unique to the UK.

Postby Harry Dalek » Mon Apr 25, 2022 5:02 pm

Steve Anderson wrote:That e-mail (the Samart one) is well and truly dead now, perhaps around the time the article was published...use the PM function here or my e-mail address on the NBTVA website.

Basically if the video system has an element of 50Hz in the video waveform, then an analogue VCR should record it. There are 'get arounds' for those NBTV systems running a 25/12.5Hz frame-rate too, which are quite simple.

Steve A.

I should have said, "Any European VCR", Unless a US (or other 60Hz machine) is multi standard, it probably wont work...


Its still in the PDF of the newsletter index Oh well every thing go's out of date in time .

OH so a NBTV could be recorded on a VCR ~! i think i tried a vcrs audio tracks but didn't have much luck may be it was the VCR i used .
So as long as the frame rate is either 12.5 25 50 it will record it with the right vcr worth an experiment next time i get them out of their boxes .

I do have a PAL 625 line to NTSC 525 line colour converter or visa versa have not used that in a long time ,VCRs at the end most of the time could do PAL NTSC or SECAM its like why bother making different models end one can do them all ...i never got into the analog HD recorders but did pick one up second hand a while ago .
I forgot to mention Melbourne in the late 40s the did 405 line experiments here, Sydney went right to 625 line even back then the city wars for Television Started right away .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 5364
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Re: 405 Line Stuff - Almost unique to the UK.

Postby Steve Anderson » Mon Apr 25, 2022 6:10 pm

With a 'standard' domestic 625 VCR you need to fool it into thinking it's recording a standard 50Hz field-rate 625 signal when it's actually recording a 12.5Hz NBTV signal. You can basically forget the colour, if there's no colour burst in the input signal, the colour circuits are effectively switched off.

Then it comes down to getting the capstan to lock with the pseudo-TV signal of which it's expecting 50Hz field-rate signal as well as the head drum.

So going back to where this started...405 can be recorded on most 625 VCRs...

Using the analogue (linear) sound track(s) of a VCR doesn't surprise that it wasn't so good. Most TVs can't reproduce 100Hz audio, forget anything lower, likewise the HF end, maybe 10kHz? ...and that's with clean tape-heads! How many people actually cleaned their VCR tape-path? Virtually zero I would say. 'Head-cleaning tapes', OK, let's not bother with them...better to use sandpaper!

Steve A.

I forgot to add...those VCRs with Hi-Fi audio tracks may have faired better recording the NBTV waveform - I've not tried it.
User avatar
Steve Anderson
"Fester! Don't do that to 'Thing'"
 
Posts: 5360
Joined: Fri Mar 30, 2007 10:54 pm
Location: Bangkok, Thailand

Re: 405 Line Stuff - Almost unique to the UK.

Postby Harry Dalek » Mon Apr 25, 2022 9:57 pm

Steve Anderson wrote:With a 'standard' domestic 625 VCR you need to fool it into thinking it's recording a standard 50Hz field-rate 625 signal when it's actually recording a 12.5Hz NBTV signal. You can basically forget the colour, if there's no colour burst in the input signal, the colour circuits are effectively switched off.

Then it comes down to getting the capstan to lock with the pseudo-TV signal of which it's expecting 50Hz field-rate signal as well as the head drum.

So going back to where this started...405 can be recorded on most 625 VCRs...

Using the analogue (linear) sound track(s) of a VCR doesn't surprise that it wasn't so good. Most TVs can't reproduce 100Hz audio, forget anything lower, likewise the HF end, maybe 10kHz? ...and that's with clean tape-heads! How many people actually cleaned their VCR tape-path? Virtually zero I would say. 'Head-cleaning tapes', OK, let's not bother with them...better to use sandpaper!

Steve A.


I will kept this information on my to do list as i said i have a few vcrs in storage from Umatic to SuperVHS it would be interesting to see ,i only ever tried recording NBTV to the Sound track very interesting ...
The show below i used to Love the episode on Television and VCRS were my favorites VCR ep below .

youtu.be/gOULWR4h4Io
BTW did you know the magnetic video recorder was invented at least on paper in 1929 translated below
279001517_10228854745533091_18432326690172941_n.jpg

Illustrierte Technik für Jedermann: Heft 44 1929
Speech is transformed into electromagnetic field fluctuations
induced, which can be heard again as speech in the headphones.
- On this principle and that of image telegraphy respectively. of
On television, Mihaly built his latest invention “The film image
on steel wire ”. This time he fixes the language instead of the language
individual pixels that are converted into electrical current values
are on the steel wire, it takes it from this again inductively
and transforms them into individual pixels.
A bright lens throws the one to be recorded
Image on a focusing screen just like a photographic one
Apparatus (Fig. 2). A Nipkow disk (Fig. 3) with a spiral shape
holes arranged in a spiral shape (gradient of the spiral equal to image image height,
height, image height, distance between the individual holes equal to image width)
the focusing screen down to a point whose rays of light shine through
one of the holes in Nipkow's disk onto a photocell
fall. Since the Nipkow disk rotates very quickly, it will
the image on the screen, point by point, line by line
scanned from top to bottom. According to these individual,
The photocell becomes a photocell with different intensities of the pixels
cell photocell exposed to different intensities, so that more or less electricity
reaches the electromagnet via an amplifier and this
again the steel wire sliding past him more or
less magnetized. So you can see that the steel wire ent accordingly
is magnetized according to the brightness values ​​of the image.
The conversion of the magnetic field fluctuations into
individual pixels are done in the same way as in the above
declared parlographers, with the difference that the
Picture 2. Film image on steel wire, Mihaly's latest invention
Instead of language as in parlographs, electricity values ​​are converted into electricity
values ​​converted image points fixed on the steel wire and from it
removed again
The magnetic fields of different strengths slide past
the steel wire in the coil induced current surges through a
Amplifier a spot light lamp (super frequency lamp) of strength
of the magnetic field on the steel wire accordingly more
or less light up. It should be mentioned here that the
Super frequency lamp almost inertia with regard to its brightness
values ​​follows the inductive fluctuations, so that in fractions
one hundredth of a second light and dark values ​​next to each other
can lie. The varying light of the super frequency lamp
so the individual, differently strong points of light fall one after the other
one after the other through the one just in front of the point lamp
Hole of the Nipkow disk through a lens on a linen canvas.
wall. Canvas. This one in its strength varying point of light feels
the first line on the screen. Then come through that
next hole the following varying light beam and probes the
second line and so on, until the last hole of the Nipkowschen
Disc scans the bottom line.
The images generated in this way are good provided that the
mechanical execution of the entire apparatus, especially
but the Nipkow disk, which is used in both the transmitter and the
Receiver must run synchronously, is perfectly fine. And
that is practically very difficult. That's why you can see today
both with film images on steel tape and with television
still the individual lines; but otherwise the pictures are flawless.
wall-free. perfect. The magnetic field fluctuations can also occur
a wireless transmitter whose waves are sent by
receive any radio sets with connected imaging devices
catch can be received.
If we now consider this new invention by Mihalys of the
economic side - so advantages and disadvantages are self-evident.
of course. Of course. A film image on steel wire has the advantage that one
immediately after taking the picture can see changes
can be carried out immediately, development etc. is omitted,
the treatment of a steel wire can be a more robust than
that of the celluloid film and a fire hazard is excluded.
But the original steel wire that holds the original image loses
gradually loses, since layer over layer, the individual elements
its magnetic field strength, although by amplification to the
Part can be retrieved again, but a flawless one
It is no longer the original.
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 5364
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Re: 405 Line Stuff - Almost unique to the UK.

Postby Klaas Robers » Tue Apr 26, 2022 1:59 am

405 video may be will only be recorded if you feed the VCR with a base band video signal. Many VCR's record from an RF-signal and then 405 line is modulated in positive AM modulation, while CCIR 625 line and other TV-systems are modulated in negative AM modulation. This will imply that the V-sync pulse will not be detected, as it will have the wrong polarity.

On the other hand, if you have to modulate the video signal yourself, you may use the negative modulation as well for the 405 line 50 Hz signal. Then the VCR behaves just like a 625 line 50 Hz TV signal. The problem is then in the play back chain, because the VCR then sends a negative modulated TV signal, while the 405 line TV expects a positive modulated signal.

So doing things in base band video solves quite some problems. Question then is: are there 405 line TV's with a video input, and / or is that input easy makable? I expect that 405 line TV's all have the internal ground connected directly to the mains.....
User avatar
Klaas Robers
"Gomez!", "Oh Morticia."
 
Posts: 1656
Joined: Wed Jan 24, 2007 8:42 pm
Location: Valkenswaard, the Netherlands

Re: 405 Line Stuff - Almost unique to the UK.

Postby Steve Anderson » Tue Apr 26, 2022 2:27 pm

Oh yes, I should had made that clearer, that here it's all baseband video, not RF modulated. Those of us that are 60+ years will remember those dual-standard TVs for the UK market due to both standards (405 and 625) being transmitted simultaneously, with different programs being aired in one standard or the other, rarely both at the same time.

So two different tuners, two different horizontal timebase frequencies, and all the electromechanical switching required. These 'monsters' were unreliable due to all that switching yet still needed to be affordable to the public. I'm glad I never had to work on one...

Steve A.

I wonder, has any other country had to transition for one major standard to another? Excluding the analogue to digital transition which every county has already done or in the process of doing so.
User avatar
Steve Anderson
"Fester! Don't do that to 'Thing'"
 
Posts: 5360
Joined: Fri Mar 30, 2007 10:54 pm
Location: Bangkok, Thailand

Re: 405 Line Stuff - Almost unique to the UK.

Postby Dave Moll » Tue Apr 26, 2022 5:49 pm

Certainly France had dual-standard sets operating on both their 625-line system and earlier 819-line system. Like in the UK, they even had dual-standard sets that operated in colour on 625 lines (though using SECAM in the French sets rather than the PAL used in UK).
User avatar
Dave Moll
Anyone have a spare straightjacket?
 
Posts: 460
Joined: Tue Feb 27, 2007 9:11 am

Next

Return to Off Topic

Who is online

Users browsing this forum: No registered users and 11 guests

cron