SSTV NBTV ?

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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SSTV NBTV ?

Postby Harry Dalek » Sun Sep 30, 2018 12:19 am

I came across this a posting from chris long on facebook a tv system bit like slow scan tv and a bit like NBTV \
For those without face book heres what i found
https://www.facebook.com/groups/1522320 ... 778730135/
https://www.facebook.com/search/str/ZL2 ... ded_videos
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ANOTHER TEST of high-speed SSTV using ZL2AFP software, in the lead up to tests of MOVING picture narrow-bandwidth TV. Vic Brown G3SDQ transmitted 72-line images of his London (UK) shack briefly on 3712.5kHz (80 metres), which I received and recorded via the Hack Green online web-SDR, about 200km to the North-West of Vic in Cheshire. He transmitted one picture every three seconds. I decoded the pictures from the Hack Green audio stream, here at VK3AML in Melbourne, Australia. Each Saturday morning between 07:30 and 08:00 UTC, the narrow band TV net in UK experiments with new methods of NBTV on 3712.5kHz plus or minus QRM. Please, if you're within range in Europe, do join us!
nbtv14608748_10207673652099122_4436952502117059623_o.jpg

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Chris Long Last week, we tried the 48-line version of the ZL2AFP software, transmitting one picture per second:


14316710_10207502867069603_8237285228823874544_n.jpg

In the WATERFALL DISPLAY of the audio stream produced by the ZL2AFP software, you can see the 96 subcarriers, one per picture scan line, each modulated by very narrow bandwidth FM - in fact if you look hard you can almost see a negative image of me in the waterfall. This is an entirely analog process, though it uses multiple subcarriers similar to OFDM technique:WATERFALL DISPLAY of the narrow band video signal used for this test. Each of the 72 lines of the image are simultaneously scanned, and each line is allocated a separate NBTV audio tone, spaced about 30 Hz apart, frequency modulated by the greyscale values, and occupying a band of frequencies from about 300 Hz to 2600 Hz:
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As below he says you will not find the software on the net well that was 2016 ? fft-tv.zip any case very interesting may be its there now ....i found one link to download the file but it was dead link sadly.



Chris Long By the way, the software that was used for those tests was not on the page for which you gave the url. It is a development from it, also by Con Wassilieff ZL2AFP, and as far as I know it's unpublished, but I can give you the zip files if you message me.
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NBTV14673047_1794848200791138_126984208504586240_n.mp4
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nnbbttvv14673047_1794848200791138_126984208504586240_n.mp4
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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: SSTV NBTV ?

Postby Monochrome » Mon Oct 15, 2018 1:53 am

Hi Harry,

Trawling through the posts in an effort to catch-up on NBTV activity I stumbled upon your posting "SSTV NBTV" and was very interested in the item about fft-tv.zip

I have experimented with Con's software in the past so I was delighted to learn of the existance of fft-tv.zip though sadly a quick search on the Internet revealed only a couple of dead links for that package.

Would it be possible for you to e-mail me a copy of the zip as I would like to give that one a try?

Regards,

Des (aka Monochrome & M0AYF)
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Re: SSTV NBTV ?

Postby Harry Dalek » Mon Oct 15, 2018 2:47 pm

Monochrome wrote:Hi Harry,

Trawling through the posts in an effort to catch-up on NBTV activity I stumbled upon your posting "SSTV NBTV" and was very interested in the item about fft-tv.zip

I have experimented with Con's software in the past so I was delighted to learn of the existance of fft-tv.zip though sadly a quick search on the Internet revealed only a couple of dead links for that package.

Would it be possible for you to e-mail me a copy of the zip as I would like to give that one a try?

Regards,

Des (aka Monochrome & M0AYF)


Hi Des i went looking for it as well and came up with the same dead link :roll:
i think chris long mentioned in these postings on face book if you contacted him and he will pass on a copy might be best to contact him on Facebook messager.
I should mention FreeNBTV i think can do something similar you can drop the frame rate or increase it in the program very handy to make a video file or live video for a custom tv format ...so i am pretty sure it could copy the software chris long was using above as far as the line and frame rates ...but in NBTV system not a speeded up SSTV FM
viewtopic.php?f=8&t=2458&p=23241&hilit=freenbtv#p23241
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: SSTV NBTV ?

Postby Monochrome » Tue Oct 16, 2018 5:58 am

Hi Harry,

Thanks for responding and for the pointers to Chris Long. Sadly I dont have a Facebook account but I may be able to find a work around ;-)

Re Free NBTV, I did try that one but have (so far) not been able to get it working on my laptop. When time permits I will give it another go on my old desk-top machine. It really is an impressive looking software tool for nbtv work.

Thanks again for taking the time to respond.

73,s

Des (aka Monochrome & M0AYF)
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Re: SSTV NBTV ?

Postby Harry Dalek » Tue Oct 16, 2018 3:45 pm

Monochrome wrote:Hi Harry,

Thanks for responding and for the pointers to Chris Long. Sadly I dont have a Facebook account but I may be able to find a work around ;-)

Re Free NBTV, I did try that one but have (so far) not been able to get it working on my laptop. When time permits I will give it another go on my old desk-top machine. It really is an impressive looking software tool for nbtv work.

Thanks again for taking the time to respond.

73,s

Des (aka Monochrome & M0AYF)


Des use the last version of Free NBTV on page 3 ,the version on page 1 you needed extra drivers version 2 and 3 don't have this problem ....if you have problems working it out my postings on that topic pages and helped me work it out but i can help if you want its easy like every thing once you know so just ask here i will keep an eye out .
The sstv software i will see if i can track it down as well ,i wouldn't mind it it does look interesting .
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: SSTV NBTV ?

Postby Monochrome » Fri Oct 19, 2018 6:31 am

Hi again Harry,

Thanks for the reply and for the pointers.

I am pretty sure it was the newest version of Free NBTV I downloaded/tested but I will double check next time I fire-up the laptop and also make a note of the errors.

73,s

Des.
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Re: SSTV NBTV ?

Postby Harry Dalek » Fri Oct 19, 2018 10:00 am

Monochrome wrote:Hi again Harry,

Thanks for the reply and for the pointers.

I am pretty sure it was the newest version of Free NBTV I downloaded/tested but I will double check next time I fire-up the laptop and also make a note of the errors.

73,s

Des.


There's just a few things on loading a picture to convert to what ever NBTV tv system you punch in you might not have got as i did at first but easy after that first working go.
Yes let me know how it go's.
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: SSTV NBTV ?

Postby Monochrome » Fri Oct 19, 2018 10:00 pm

Thanks Harry,

I have downloaded the newest version (again) from here...

viewtopic.php?f=8&t=2458&p=23241&hilit=freenbtv#p23241

... and will try it again and let you know what errors/problems arise. So many "boxes" with error messages popped-up last time I got confused but I will make a point of reading them all next time and noting down the specific error messages.

Thanks again.

73,s

Des.
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Re: SSTV NBTV ?

Postby Harry Dalek » Sat Oct 20, 2018 9:44 pm

Monochrome wrote:Thanks Harry,

I have downloaded the newest version (again) from here...

viewtopic.php?f=8&t=2458&p=23241&hilit=freenbtv#p23241

... and will try it again and let you know what errors/problems arise. So many "boxes" with error messages popped-up last time I got confused but I will make a point of reading them all next time and noting down the specific error messages.

Thanks again.

73,s

Des.


HI Des
Yes that's correct the one i am using too , also v2 worked fine for me as well ,just V1 needed drivers.
Looking at the original software there is also something similar Hybrid FM NBTV...
https://www.qsl.net/zl1bpu/NBTV/Hybrid.htm
software link bottom of page .
https://www.qsl.net/zl1bpu/NBTV/H-TX.htm
I have been playing with it results here
Screen 00000.jpg

here i just connected the output audio out the lap top to the input via a cable ,,you can also do a bit of audio short distance dxing via your lap top speaker to its mic and receive it ...quick test lot of room noise as well
Screen 00083.jpg
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: SSTV NBTV ?

Postby Monochrome » Sat Oct 20, 2018 11:34 pm

Hi again Harry,

Prompted by your last e-mail response I had another go with the current version of FreeNBTV software I downloaded a couple of days ago and I am pleased to report it works this time :-)

I took the precaution of using a different laptop this time around with Windoze7 and an otherwise empty hard disk so no possible corruption of system files etc from years of install/remove software Hi. Its early days yet and I need to explore all the different options but its allready clear that it will be a usefull testing tool for any non-standard NBTV mode experiments. Perhaps its time I re-read the original posts about FreeNBTV to see if any addition documentation or user instructions exist so I can take full advantage of the software.

Re the ZL1BPU software(s) for NBTV over HF links, I downloaded those a few years ago but sadly never got around to trying any of them but they do look promissing and fun :-)

BTW Harry, what Windoze version are you running with the ZLBPU software? I note on the website he comments...

" It is designed for Windows™ XP. At present there is no software for other operating systems."

Its not a problem as I now have a third laptop with Win7 installed so (in theory) I can now replicate your "audio over the air" experiment but I just wondered if you had managed to run it under some other Windoze version.

Thanks for helping to restore my enthusiasm for image communication :-)

73,s

Des.
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Re: SSTV NBTV ?

Postby Harry Dalek » Sun Oct 21, 2018 8:05 am

Monochrome wrote:Hi again Harry,

Prompted by your last e-mail response I had another go with the current version of FreeNBTV software I downloaded a couple of days ago and I am pleased to report it works this time :-)


Thats good Des its very useful ...
you must of worked most of it out but Load picture or a video via the INPUT screen window .....(its set at 32 line so just leave that you will work out how to change all the line and frame rates at leisure) but now go to the freeNBTVge.exe screen window and press file so theres a black set dot there ....then press signed and the (default) and( set format )till the picture file shows up in the box but as a wav...now you are ready to make a video file press Start button and your picture will show up in the SDL box and it will be making the video till you press stop ...look in th Freenbtv folder and your Wav video file will be there.
Theres no player yet so leave it on 32 line 12.5 for now so you can view play back the results on either Garys or Dom's player software ..also you can increase
resolution pixels perline in the software as well i did play here with it on last page on the freenbtv posting.

I took the precaution of using a different laptop this time around with Windoze7 and an otherwise empty hard disk so no possible corruption of system files etc from years of install/remove software Hi. Its early days yet and I need to explore all the different options but its allready clear that it will be a useful testing tool for any non-standard NBTV mode experiments. Perhaps its time I re-read the original posts about FreeNBTV to see if any addition documentation or user instructions exist so I can take full advantage of the software.


Theres not much on how to use it but i really like it ,yes also i used it on windows 7 i dislike 10 and i have not tried it on xp that could of been your problem ?

Re the ZL1BPU software(s) for NBTV over HF links, I downloaded those a few years ago but sadly never got around to trying any of them but they do look promissing and fun :-)


He has a lot of software ,i tend to stay away from the digital stuff but do like analog Am or Fm this one reminds me of SSTV

BTW Harry, what Windoze version are you running with the ZLBPU software? I note on the website he comments...

" It is designed for Windows™ XP. At present there is no software for other operating systems."


Well that worked fine on windows 7 ! so thats good.

Its not a problem as I now have a third laptop with Win7 installed so (in theory) I can now replicate your "audio over the air" experiment but I just wondered if you had managed to run it under some other Windoze version.

Thanks for helping to restore my enthusiasm for image communication :-)

73,s

Des.


No worries BTW heres a rather rarer sstv program i like if you have not seen it .
viewtopic.php?f=25&t=2350

Below a touch better air transmitting from mic to speaker of the FM NBTV
Screen 00085.jpg
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: SSTV NBTV ?

Postby Monochrome » Sun Oct 21, 2018 9:57 pm

Hi again Harry,

Thanks for the pointer to Classic SSTV by G4IJE, I look forward to trying it out with a webcam. The only issue might be the requirement to have the .net framework installed. I have nothing against .net its just that some times when you do a Windows update it might include .net framework components which seem to take forever to download/install.

Thanks for the additional tips for using FreeNBTV and for the time being I will stick to the defaults until I feel confident enough to start using custom settings. I will also have to look at the output on a CRO to see how good the LF response of the soundcard is.

So often this can be an issue when trying to feed external sources. Likewise, the lower frequency limit can be an issue when feeding NBTV signals into a PC or laptop. I had an issue when I fed the output of my EPROM caption generator into a PC running "The big picture" software. The sync was a bit ropey to say the least.

Harry wrote:
He has a lot of software ,i tend to stay away from the digital stuff but do like analog Am or Fm this one reminds me of SSTV
**************

Yes, I much prefer analog to digital. Indeed, I lost interest in fast-scan ATV a few years ago due to the dash-for-digital. The picture quality of digital modes is superb but it was all to much like "skype" for me :-) I much prefer the weak and sometimes flickery images of a borderline analog signal. Plus the added advantage of "real time" viewing with analog fstv, no latency due to digital processing etc.

I look forward to playing with those software(s) laptop-to-laptop and possibly via a short range optical link (another of my interests) thanks to the freely available high power LED's at low prices.

Cheers for now,

Des.
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Re: SSTV NBTV ?

Postby Steve Anderson » Mon Oct 22, 2018 2:21 pm

Monochrome wrote:...I will also have to look at the output on a CRO to see how good the LF response of the soundcard is. Des.

Hi Des, This is something I was concerned with some years ago...

'Soundcards' (for want of a better name these days), are usually designed to drive earpieces or headphones of around 32 Ohms. They usually run off the +12V internal supply so there's a capacitor to provide DC isolation in series with the earpieces/headphones of a value which provides around -3db response at somewhere near 20Hz.

If your external gear has an input impedance of 1k that -3db point drops to around 0.7Hz, even lower for higher impedance loads.

I did test this out and confirmed what I had guessed.

Steve A.

The output will take quite a while to settle to being zero volts with no output as it takes longer for those capacitors to charge with the higher impedance load at switch-on, several minutes possibly.

When recording there's not a lot you can do about a poor LF response unless you don't mind 'knife and forking' your mainboard. Some software also have a 'software capacitor' in the code so it simply can't record anything sub-audible. Warped LPs can generate large sub-sonic signals...you do not want those to reach your expensive hi-fi speakers...
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Re: SSTV NBTV ?

Postby Monochrome » Thu Oct 25, 2018 1:49 am

Hi Steve,

Thankyou for commenting on the subject of soundcard frequency response and for sharing your experience.

[quote]
'Soundcards' (for want of a better name these days)...[/quote]

I take your point, perhaps "audio interface" might be a better term in these days of laptops, note-books, desk tops and tablets etc?

[quote]
If your external gear has an input impedance of 1k that -3db point drops to around 0.7Hz, even lower for higher impedance loads.[/quote]

Most of my home-brew nbtv will be in that ball-park input impedance value so it looks as though everything should be ok at least for signals comming from the computer. I also share your concern about the coupling capacitors and longer time constants with higher load impedances causing the video waveform to "bounce about" a little.

[quote]When recording there's not a lot you can do about a poor LF response unless you don't mind 'knife and forking' your mainboard.[/quote]

Its interesting you should mention that, while 'knife and forking' the main board could be risky and expensive it might be possible to hack one of those cheap USB plug-in audio modules as used on the likes of raspberry-pi. I saw an item on the web describing the use of a "hacked" USB sound-card in order to provide DC-coupling for one of the many PC-CRO software packages available.

With the addition of a circuit to compensate for any DC offset it might be a way of obtaining VLF response when recording nbtv. While the audio quality and noise floor of some of those cheap soundcards is not great it would probably suffice for nbtv applications. Heres the link...

https://hackaday.com/2015/11/04/one-dol ... d-o-scope/

BTW one of the CRO software packages mentioned in the comments appears to be very good and might be usefull for nbtv. I have only tried it briefly but it seems failrly comprehensive including an x-y mode and audio signal generator functions.

https://www.zeitnitz.eu/scope_en

I have not attempted the sound-card hack myself (yet) but it is on the to-do list :-)

Thanks again Steve for taking the time to respond.

73,s

Des (aka Monochrome & M0AYF)



Not all the USB sound interfaces are hackable and of those that are it needs some carefull soldering to remove and/or short the capacitor(s) out.
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Re: SSTV NBTV ?

Postby Steve Anderson » Thu Oct 25, 2018 2:30 pm

Monochrome wrote:Most of my home-brew nbtv will be in that ball-park input impedance value so it looks as though everything should be ok at least for signals comming from the computer. I also share your concern about the coupling capacitors and longer time constants with higher load impedances causing the video waveform to "bounce about" a little.

As I recall (but don't quote me) the output coupling caps on my HP desktops were 100uF, with a 32 ohm load that's a -3db point of 50Hz - pretty crappy even for music let alone NBTV. They usually have a series resistor of a similar value to protect against short-circuits on the output. This brings the -3db point to a more respectable 25Hz or so.

When the load is 1k or greater that internal resistor can be forgotten about. I tend to go for a 10k minimum input impedance to NBTV stuff followed by a unity gain (Av +1) op-amp (though a non-inverting op-amp with gain will be OK) or a transistor emitter-follower.

The longer time-constant (say 100uF and 10K = 1 second) will cause the video waveform to drift slowly up and down with changes in APL (Average Picture Level). But it will be a vast improvement compared to the usual 32 ohm load. This followed by a DC-restorer is all you need, Klaas Robers design for example, simple and it works.

However, we still have the bug-bear on the input. You could either reverse-engineer the input side by having a look inside or measuring the input impedance at 1kHz and then finding the input -3db point. From this you could build a circuit that has the inverse LF boost just to get around that input cap. But if there's another one downstream that makes things really awkward!

Not forgetting the 'software capacitor' if the code has one...

I'll have a look at those links when I can...

Steve A.
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