405/625 lines SSTV system

Forum for discussion of SSTV topics. Slow Scan television (SSTV) is a picture transmission method used mainly by amateur radio operators, to transmit and receive static pictures via radio in monochrome or colour.

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405/625 lines SSTV system

Postby OmegaProductions » Sat Dec 02, 2017 9:05 am

Hello guys in NBTV! :D

And today, I have an another creative idea. I have already done the widescreen SSTV format, but now let's talk about this SSTV system I thought of... Well, you know that most analogue TVs have 405 and 625 lines, but for SSTV, they only have 250 lines (Betamax quality). Why not improve the quality of SSTV up to 405/625 lines of pictures? That might be interesting to research and look at!! :D However, I may not do the system, since I don't know how to actually decode higher line resolutions. :?

However, it might be good if you ask me questions about ideas for this system. Anyways, that's all I had to say! This is me Dylan signing off and goodbye!!!! :D :) :wink:
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Re: 405/625 lines SSTV system

Postby Harry Dalek » Sat Dec 02, 2017 5:28 pm

OmegaProductions wrote:Hello guys in NBTV! :D

And today, I have an another creative idea. I have already done the widescreen SSTV format, but now let's talk about this SSTV system I thought of... Well, you know that most analogue TVs have 405 and 625 lines, but for SSTV, they only have 250 lines (Betamax quality). Why not improve the quality of SSTV up to 405/625 lines of pictures? That might be interesting to research and look at!! :D However, I may not do the system, since I don't know how to actually decode higher line resolutions. :?

However, it might be good if you ask me questions about ideas for this system. Anyways, that's all I had to say! This is me Dylan signing off and goodbye!!!! :D :) :wink:


Well we are talking fax sort of here then .
infact the noaa weather satellites the line rate is really endless if it were possible to follow it ,http://www.geo-web.org.uk/apt.php
2 lines a second about 120 lines a minute 15 minutes a picture /
Not sure of the line rates of the higher SSTV systems they would all be in the software you have .
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.
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Re: 405/625 lines SSTV system

Postby OmegaProductions » Sun Dec 03, 2017 2:11 am

Harry Dalek wrote:Well we are talking fax sort of here then .
infact the noaa weather satellites the line rate is really endless if it were possible to follow it ,http://www.geo-web.org.uk/apt.php
2 lines a second about 120 lines a minute 15 minutes a picture /
Not sure of the line rates of the higher SSTV systems they would all be in the software you have .


Oh yeah I noticed! :| SSTV programmes hasn't really got those kind of higher line resolutions settings yet. If they had a custom settings and you could enter the number you want, I would enter in 405 or 625 lines, but they hadn't add it yet. Or if someone made their own programme of SSTV including custom line resolutions! :D

However they hadn't had those advanced stuff yet really. But it would be interesting though. :) :idea:
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Re: 405/625 lines SSTV system

Postby ppppenguin » Tue Dec 05, 2017 2:01 am

Fax and TV are very much the same thing, a means of transmitting images. The main difference is the speed at which it happens. Many are surprised that Fax predates the telephone by 30 years or so: https://en.wikipedia.org/wiki/Alexander_Bain_(inventor)#Facsimile_machine

The scanning theory which underpins both fax and TV was first formally set down in 1934 in a classic paper by Mertz and Gray:
https://archive.org/details/bstj13-3-464

The maths is heavy for most (there was a time many years ago when I reckon I could understand most of it in detail) but the ideas are clear enough. The most startling prediction they make is about utilising the sparesly occupied spectrum of a transmitted picture for sending another picture in the same channel. This was picked up more than 10 years later for NTSC and PAL colour.

Note the title: "A Theory of Scanning and Its Relation to the Characteristics of the Transmitted Signal in Telephotography and Television". Telephotography is another word for fax.
Jeffrey Borinsky www.borinsky.co.uk
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Re: 405/625 lines SSTV system

Postby OmegaProductions » Tue Dec 05, 2017 3:51 am

Oh yeah...I noticed! Television and fax machines are both relative, but different uses. It's only relative technology because they scan an image line-by-line, and both do the same. Thanks for spotting that out!! :)
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Re: 405/625 lines SSTV system

Postby OmegaProductions » Tue Dec 05, 2017 8:03 am

Hello guys again!! :D :)
I just have a message, I had this programme (which is rubbish! :x ) and it was made in 2002, 15 years ago! And it was supposed to be a 60-line SSTV?? :shock:

I had a photo of my fake Oscar award toy as a test subject for my camera to 60-line SSTV image. Well...when I tried it, it didn't really pick it up, so I used a speaker to amplify it, just like in my iPad, but in the computer in this programme. When I did it, it sort-off picked up a tiny-bit of picture, but just a line fragment of it. And I didn't test it out much, because of my sensitive ears, and it makes me sick!! :oops: And obviously the neighbours might hear the terrible signal!! :shock: But anyways...here is the screenshot with the picture fragment. Anyways...this is me Dylan signing out and goodbye!!!! :D :) :wink:
60 line screenshot.png
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Re: 405/625 lines SSTV system

Postby Andrew Davie » Tue Dec 05, 2017 10:30 am

OmegaProductions wrote:Hello guys again!! :D :)
I just have a message, I had this programme (which is rubbish! :x ) and it was made in 2002, 15 years ago! And it was supposed to be a 60-line SSTV?? :shock:



You never know who you may offend with an off the cuff remark like that. 15 years is a long time in computing, and tools and capability have changed an awful lot since that program was written. Rather than telling us how bad it is, how about writing a better one yourself?
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Re: 405/625 lines SSTV system

Postby OmegaProductions » Tue Dec 05, 2017 6:39 pm

Whoops! Sorry... :\
I think you are right Andrew... It is old though and it wasn't good back in those computing times. I did tried to try the signals to recognise it, but it seems to not pick it up. :\
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Re: 405/625 lines SSTV system

Postby OmegaProductions » Wed Dec 06, 2017 9:24 am

Wait! Nevermind! :!: I realise how to solve the problem and how I actually use the 60-line SSTV app.

It wasn't the programme that was rubbish, it was my terrible microphone on my computer! Silly me! :|
Even though I had the speaker to amplify the signals, I think I should adjust my microphone with Audacity or use a separate microphone, even though my computer does not have the microphone jack connectors. I'll just try again in a second attempt, before we research more about 405/625 line SSTV format. Well that's all I had to say! This is me Dylan signing out and goodbye!!!! :D :) :wink:
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Re: 405/625 lines SSTV system

Postby Harry Dalek » Wed Dec 06, 2017 5:24 pm

OmegaProductions wrote:Wait! Nevermind! :!: I realise how to solve the problem and how I actually use the 60-line SSTV app.

It wasn't the programme that was rubbish, it was my terrible microphone on my computer! Silly me! :|
Even though I had the speaker to amplify the signals, I think I should adjust my microphone with Audacity or use a separate microphone, even though my computer does not have the microphone jack connectors. I'll just try again in a second attempt, before we research more about 405/625 line SSTV format. Well that's all I had to say! This is me Dylan signing out and goodbye!!!! :D :) :wink:



60 line sstv ? i have done something similar on past mechanical scanning pictures drawings at the wrong speed early results
viewtopic.php?f=23&t=1890&start=105
i also used MMSTV to view .... i know of no sstv programs that will do this in 60 line
Your sure that's not a early NBTV program ? seems likely 60 lines/
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.
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Re: 405/625 lines SSTV system

Postby OmegaProductions » Wed Dec 06, 2017 6:32 pm

Oh no! I got mistaken! They said online that it was a 60 line SSTV, but I realise that it was a NBTV player. Oops! :oops:
Sorry for the mistake! :|
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Re: 405/625 lines SSTV system

Postby Klaas Robers » Wed Dec 06, 2017 10:13 pm

60 lines SSTV, that was quite common in the beginning years. It was just a 120 lines SSTV signal, but vertically half way there was a vertical sync pulse (half a line) and then most SSTV monitors started to jump to the top of the screen. If you just wanted to transmit one small sentence, or just your call sign, then this could be used. A picture then took just 3.6 seconds in an aspect ratio of 2 : 1 (hor : vert).

Even quarter pictures were sent, so 30 lines in 1.8 seconds in an aspect ratio of 4 : 1. All monitors could receive that. For some monitors (e.g. mine) you got 2 or 4 identical pictures above each other. My monitor accepted a V-pulse only in the bottom 10% of a picture.
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Re: 405/625 lines SSTV system

Postby OmegaProductions » Thu Dec 07, 2017 9:11 am

WOW! That's interesting Klaas! :D :)

I'm still thinking ideas of how to make 405/625 line SSTV to practice use. :) But I would want to see a 30-line SSTV machine though! :wink:
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Re: 405/625 lines SSTV system

Postby Harry Dalek » Thu Dec 07, 2017 2:15 pm

Well this is what 32 line SSTV looks like my invention by mistake scanning about 32 lines over 8 seconds as i recall .
My picture is rotated by a stepper motor they are pretty good at keeping correct speed then i just hand scan with light sensitive diode controlling a voltage controlled oscillator which varies frequency to the light levels ...its adjusted to vary depending on light or dark levels ...frequencies adjusted to be in the SSTV range you see on the mmsstv scope .
Very simple like a early fax machine scanning a photo....apart from me moving the scanning device by hand down the rotating image .
So the line speed 4 hz instead of 15hz 15hz times 8 sec 120 lines ...4hz times 8sec 32 lines

That's why the last link page was 64 line 8 hz line speed horizontal and 8 sec vertical..
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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.
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Re: 405/625 lines SSTV system

Postby OmegaProductions » Thu Dec 07, 2017 6:37 pm

WOW!! That's fascinating! :D It also reminds me of the early fax machine from the 1900s like a cylinder. I saw this in "The Secret Life of Machines" in a fax episode. Like that invention Harry!! :wink:

Anyways...I'll see you later! This is me Dylan signing out and goodbye!!!! :D :) :wink:
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