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Forum 141

What standards Convertor?

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Marc
 Marc
(@marc)
Posts: 2753
Noble Member Registered
 

Cathovisor said
Having watched it recently, I wouldn't bother. Not one of Mr. Rosenthal's best efforts.  

Yes I seem to remember in the dim and distant past, it was just watching the all the equipment around the studio that I liked but not the story line, at least we got 10 minutes of footage out of the hour and a half hmm_gif

Marc.

Marc
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RSGB call sign 2E0VTN

 
Posted : 10/10/2016 12:34 pm
Terrykc
(@terrykc)
Posts: 4005
Member Rest in Peace
 

Cathovisor said
Thinking of modulators always had me wondering how nice it would be if someone could design/build a multi-channel, vestigial sideband modulator for System A. One that covered channels 2-13. As ever, the shaping filter would be the hard bit.

I was giving this some thought a couple of years ago when I came across a spec for a system I SAW filter. Unlike the analogue IF SAW filters I think everybody will have encountered, for DTV the entire 8MHz channel is required so I wonder if it might be possible to retrieve some from old set top boxes.

Then an IF modulator could be sent through the SAW to lop off the unwanted lower side-band before being up-converted to broadcast frequencies - by effectively using a 13 Channel tuner in reverse.

SAW-System_I_with-System-A-overlay.png

Would 40dB rejection of the Vestigial side-band at the adjacent sound carrier be sufficient - I'm assuming that video frequencies above 3MHz can be suitably attenuated without too much bother - it would, by juggling the IF frequencies slightly be possible to 'drop' the adjacent sound carrier into a much deeper notch but if the sound and vision carriers are somewhere about equal I wouldn't expect any trouble.

Well, there's a VSB solution - anybody fancy giving it a go?

When all else fails, read the instructions

 
Posted : 11/10/2016 7:13 pm
Terrykc
(@terrykc)
Posts: 4005
Member Rest in Peace
 

I looked in the library for information relevant to this topic but, when I got to: Miscellaneous Data / Standards Converters /Modulators 405 & 625 and clicked the link, it took me back to the index again - although the page address looks correct:

https://www.radios-tv.co.uk/miscellaneous-data/?drawer=Miscellaneous%20Data*Standards%20Converters*Modulators%20405%20&%20625

Is there a mistake somewhere or am I doing something wrong?

When all else fails, read the instructions

 
Posted : 12/10/2016 10:44 am
crustytv
(@crustytv)
Posts: 11905
Vrat Founder Admin
Topic starter
 

Terry said
Is there a mistake somewhere or am I doing something wrong?  

Yes my mistake and nothing you're doing wrong.

With all the recent major changes, the data library underwent a migration to a new software delivery package, it took over some empty folders. I did manual tidying but obviously missed the one you've just found. That folder structure was created a long time ago with the plan of acquiring all the schematics for all the convertors that were produced, I never found any a lofty goal long ago abandoned. The folder structure remained empty, I should have removed it, I have now.

It would seem but I need to check, if the software detects an empty folder it just returns the user query to the top level. I'm not surprised there are a few bugs to be found, the forum software and data delivery software are two very new packages there are likely others that will be discovered over time. This has prompted me to do further checks for other such omissions and it may just be a setting I've missed for empty folders under miscellaneous.

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Posted : 12/10/2016 11:13 am
peterscott
(@peterscott)
Posts: 1028
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Before the Aurora was available I built a converter based on Darius Mottaghian's design. I tried it again recently and it still works fine.

http://normwandler.blogspot.co.uk/2008/11/normwandler-mk-i-einfhrung.html

Peter

www.nostalgiatech.co.uk

 
Posted : 11/11/2016 4:22 pm
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