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-   -   IMOGen Test Card & Teletext Generator (https://www.vintage-radio.net/forum/showthread.php?t=77624)

terrykc 6th Mar 2012 10:48 am

Re: IMOGen Test Card & Teletext Generator
 
Quote:

Originally Posted by Parabola (Post 510429)
... Sorry about the weather outlook. It took me about 6 hours to re-code that page back into 7 bit ascii from a .gif of the original and, to be honest, the actual forecast wasn't the highest priority in my mind ;) ...

It's quite a coincidence that the forecast you 'brought back from the dead' bears a marked similarity to the weather we've been experiencing over the last few days!

Quote:

Originally Posted by Parabola (Post 510429)
IMOGen puts out 12 lines per field, so the page counter between page selections moves like a blur! I was a little concerned at first as to whether so many lines would be tolerated by such an early decoder as is in the G11 ...

All versions of the UK Teletext Specification (there were three) specified that all 16 available lines in the VBI could be used. Although the early TIfax decoder was designed before the 'new' features (background colour, double height, etc.) were added, it worked on all 16 lines.

I know what you mean about the page numbers - we used 14 lines for the test pages and bridged BBC1 CEEFAX onto the remaining two.

CEEFAX was used to create interest and demonstrate the capabilities of Teletext but, in reality, the primary purpose was to test the capability of a large, private, cable TV system by means of an error counter piggy-backed onto the TIfax decoder.

Quote:

Originally Posted by Parabola (Post 510429)
Quote:

Originally Posted by terrykc (Post 510224)
... rows can be transmitted in any order.

Well yes, as long as you keep a track of where your header rows are inserted. One out of sequence data line on the wrong side of a header row and it all goes to pot!

Agreed, but it wasn't a problem with the Philips generator as the row numbers were included in the data. It was simply a case of re-ordering the data before burning the PROM.

Andy Green 6th Mar 2012 10:31 pm

Re: IMOGen Test Card & Teletext Generator
 
Excellent work Parabola! (I want one!)
This thread has reminded me to root out a S-VHS tape and record the Irish analogue stations teletext before ASO in August this year

Parabola 7th Mar 2012 11:08 pm

Re: IMOGen Test Card & Teletext Generator
 
Thanks, Andy.

Well, it's possible that there may be a spare from the initial build of 10 units, once everything shakes out. If so I'll let you know. I would possibly build more if there were to be any demand, but the PCB already needs redesigning due to one component becoming obsolete in through hole form.

Paul Stenning 8th Mar 2012 3:48 pm

Re: IMOGen Test Card & Teletext Generator
 
You can get SMT to through-hole adaptors for some IC packages. That may be an easier/cheaper option than redesigning the PCB.

Parabola 9th Mar 2012 9:37 am

Re: IMOGen Test Card & Teletext Generator
 
Thanks, Paul. Yes, that's certainly another option.

Tazman1966 2nd Nov 2012 2:06 pm

Re: IMOGen Test Card & Teletext Generator
 
Quote:

Originally Posted by Andy Green (Post 510718)
Excellent work Parabola! (I want one!)

Well you can now!

http://www.pges.co.uk/imogen/index.html

I was contacted about using my photos of my Korting showing test cards from the IMOGen and of course I said yes and they're here on his website along with plenty of information about the test card generator.

Cheers,

Tas:thumbsup:

chriswood1900 23rd Nov 2012 3:11 pm

Re: IMOGen Test Card & Teletext Generator
 
I have just taken delivery of my Imogen from Graham, very impressed and seems a bargain to me. Very useful alongside an Aurora and great fun being able to get Text back on my colour TVs. For more info have a look at the website in the link above.
A happy customer Chris

petertheorgan 23rd Nov 2012 10:21 pm

Re: IMOGen Test Card & Teletext Generator
 
4 Attachment(s)
I have also just taken delivery of my Imogen from Graham and it is a super piece of kit ! which I can well recommend ,

I have attached a few photos but they do not do it justice, perhaps it means that some full 625 restorations are in order now that I have been dragged screaming into 1967 !

another very happy customer

peter

winston_1 24th Nov 2012 12:30 am

Re: IMOGen Test Card & Teletext Generator
 
I took delivery of one last week as well. I'm delighted with it as well.


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