Fault finding

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Re: Fault finding

Postby Harry Dalek » Mon Feb 22, 2021 4:35 pm

Steve Anderson wrote:
Harry Dalek wrote:...for a future monitor 100 lines (or) over .

Well, it all depends on the bandwidth required. Which is dictated by number of lines (OK set at 100 for now), Aspect ratio, (WxH), and frame rate. Plus to an extent sync arrangements.

Say 100 lines, 1.5 Aspect Ratio and 12.5 fps. So that implies 150 line pixels. 100 lines at 12.5fps. 100 (lines) x 150 (pixels) x !2.5 (fps) = 187,500 pixels per second, a bandwidth of 93kHz. Add in a fudge-factor of 15% for syncs = approx. 105kHz. You see the problem...

The electronics isn't the problem, the storage and retrieval could be...and we haven't even touched on the audio to go with it.

The bandwidth required goes up with the square of the resolution required, all other things being equal...

Steve A.


Yes the biggest problem i see is not so much making a higher bandwidth monitor work but having a video to feed it of some sort ,i looked into this into this in the past with the making thanks to your circuits in part the cyclops vidicon multisystem camera and the NBTV Television Analyst results ,the the vidicon could be best bet for some thing around the right bandwidth like every thing put away will it still work after a few years in a box ? i could only test it with the PC monitor software we have didn't have a multisystem monitor to test it at the time ...i think a stair case grey scale test card generator might be also an easier fix for testing .
I remember you mentioning a vcr could record the video perhaps as in the storage problem ?
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: Fault finding

Postby Steve Anderson » Mon Feb 22, 2021 7:49 pm

A VCR...who has an operational one of those these days? I don't...it was a means to an end at the time, I don't intend to re-visit it. However, what has taken its place? DVDs? or other? The format would need to be uncompressed otherwise it would probably fall flat on its face.

Our best chance (as I see it today) is a USB I/O via a USB-TTL converter, in both directions. Hence my desire to do a converter for such. But that's a way down the road for now. One of the items in the queue...

Layout for the revised SSTV-VGA up-converter in progress, maximising bandwidth at the moment. Pictures should occupy 512x512 pixels of a 600x800 60Hz display. Though the actual resolution is defined my the modified Cop McDonald standard, lines sampled at 256 pixels (as before), lines a multiple of 128, in this case 512...each SSTV line repeated four times...whereas the previous 625 version only repeated twice, the 625 interlacing doing the rest..the lack of interlacing is one of the reasons for the bandwidth increase by double..oh well..progress...

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Re: Fault finding

Postby Harry Dalek » Tue Feb 23, 2021 8:24 pm

Steve Anderson wrote:A VCR...who has an operational one of those these days?


Well i have one in the house and few packed away Umatic's ,Super VHS, VHS and Beta ...operational yes last time i checked but as we know that was then now is another time .

I don't...it was a means to an end at the time, I don't intend to re-visit it. However, what has taken its place? DVDs? or other? The format would need to be uncompressed otherwise it would probably fall flat on its face.


Done with with the buggers EH ! mmmm i can understand that ...i never really got into dvd and blue ray not at all i dislike optical format as the worst form of video storage i bet Bairds PhonoVision will out live every optical disk ever made thats why i use them to scratch NBTV video on them revenge to their major flaw one scratch and their rubbish .

Our best chance (as I see it today) is a USB I/O via a USB-TTL converter, in both directions. Hence my desire to do a converter for such. But that's a way down the road for now. One of the items in the queue...

Layout for the revised SSTV-VGA up-converter in progress, maximising bandwidth at the moment. Pictures should occupy 512x512 pixels of a 600x800 60Hz display. Though the actual resolution is defined my the modified Cop McDonald standard, lines sampled at 256 pixels (as before), lines a multiple of 128, in this case 512...each SSTV line repeated four times...whereas the previous 625 version only repeated twice, the 625 interlacing doing the rest..the lack of interlacing is one of the reasons for the bandwidth increase by double..oh well..progress...

Steve A.
[/quote]

I like the idea of a stand alone unit as mentioned as your trying for SSTV so a image or avi mpg to 100 or more lines would be a useful thing on the MBTV side if we are talking not so Narrow band tv .

For me at the moment experimenting with the CRT monitor here FreeNBTV is great for syncing testing ..not so important if bandwidth drops the image Quality it did show me i can't have a tiny raster on 100 line or more ,i would be squashing the lines to the point they over lap so need to use most of the CRT face space so scanning can correctly deal with the extra lines .
There's a 120 line 12.5 and 25 frame format on http://authorityfile.co.uk/nbsc/ doms NBSC site makes me wonder how its possible for a ok image if all done on PC same gos for Garys 120 line software on the forum and thats in colour pixels per line lower ? no idea ...i would like to try it out on the monitor and see if this works well or any case results .
So lots of fun to come with the old devil monitor.
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: Fault finding

Postby Steve Anderson » Thu Feb 25, 2021 1:09 pm

Harry Dalek wrote:..it did show me i can't have a tiny raster on 100 line or more ,i would be squashing the lines to the point they over lap.

Agreed, 100 lines on an oscilloscope type 3" CRT is rather pointless. Most datasheets for these CRTs will have a specification for 'spot-size' when correctly focused etc. Usually around 0.5mm under ideal conditions, some a bit larger, 0.7mm, some, but only a few, smaller.

But for 'scope type applications that's good enough. However some 5-7" CRTs were made for TV camera viewfinders which had a much smaller spot-size to aid in focusing the camera. Until flat-panel screens came about, though the camera was colour, the viewfinder was often monochrome. Smaller colour CRT's for viewfinder use didn't have the resolution for accurate focusing. Here I'm mainly referring to studio (professional) TV cameras. The cameraman isn't interested in colour, it's framing (composition), lighting/exposure and focusing he's being paid for...and following whatever the director is shouting into his headphones.

Today a large percentage of studio cameras are robotic, up to six cameras can me controlled by one 'operator' in the studio control room (the word cameraman has almost vanished). Saves a bundle on salaries.

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Re: Fault finding

Postby Harry Dalek » Thu Feb 25, 2021 3:08 pm

Steve Anderson wrote:
Agreed, 100 lines on an oscilloscope type 3" CRT is rather pointless. Most datasheets for these CRTs will have a specification for 'spot-size' when correctly focused etc. Usually around 0.5mm under ideal conditions, some a bit larger, 0.7mm, some, but only a few, smaller.


Yes the little tubes are pushing it to show higher line rates, displaying the higher line number does take more space and as you say tiny focused dot does get smaller higher you go.
For what i am displaying at times its not to bad ..some thing i forgot doing as i was trying higher line numbers was to refocus that dot for each new system displayed it helps to refocus the CRT !

But for 'scope type applications that's good enough. However some 5-7" CRTs were made for TV camera viewfinders which had a much smaller spot-size to aid in focusing the camera. Until flat-panel screens came about, though the camera was colour, the viewfinder was often monochrome. Smaller colour CRT's for viewfinder use didn't have the resolution for accurate focusing. Here I'm mainly referring to studio (professional) TV cameras. The cameraman isn't interested in colour, it's framing (composition), lighting/exposure and focusing he's being paid for...and following whatever the director is shouting into his headphones.


I have a CRT viewfinder working the raster dot on those tiny CRTs i had to work out what its measured in microns ,can't say i ever saw a CRT colour viewfinder and as you say a tiny flat panel .

Today a large percentage of studio cameras are robotic, up to six cameras can me controlled by one 'operator' in the studio control room (the word cameraman has almost vanished). Saves a bundle on salaries.

Steve A.
[/quote]

Sad day for studio camera man i suppose all their work went mobile ,so far no robot camera men but it will come .

Today i swapped computers to test as my new lap top as it has HD Audio .
Apart from here testing the video out to the monitor i am not sure how to really test its limits .

I wanted to see today how the swap would show up on the monitor ,on the right is the line number of what's being displayed .

I think this pc's sound device is helping but there is still bandwidth loss shown going from 64 line going higher to 94 line ,even with this sound device its only a touch better getting to the 70s still looks good every bit helps and tick off the list on what to do next ..again just doing this for a future build larger CRT for a start ..learn as you fiddle !
Now i got that off my chest i will look into higher frame rates side side of it ...BTW i found the limits now to correct framing it is 23 line to 150 line the pot seems useless after that ,i would think a slight value change to ic604B 4538 monos capacitor c622 would help but this is still a fantastic range !
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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: Fault finding

Postby smeezekitty » Sat Feb 27, 2021 1:46 pm

Just want to make sure you're increasing the windowing region in FreeNBTV when you change line rates?

Because if you're only capturing 32 lines and scaling it up to more lines, of course you won't benefit from the additional lines.

But yeah of course, PC sound cards are really at their limits at those resolutions.
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Re: Fault finding

Postby Harry Dalek » Sat Feb 27, 2021 4:23 pm

smeezekitty wrote:Just want to make sure you're increasing the windowing region in FreeNBTV when you change line rates?

Because if you're only capturing 32 lines and scaling it up to more lines, of course you won't benefit from the additional lines.

But yeah of course, PC sound cards are really at their limits at those resolutions.



I have been increasing the sample rate pixels per line but no i have forgotten about scaling the photo...and also i have been swapping to a newer computer with HD sound device .

I love your program very helpful i am more than likely the first to display the other line and frame rates it can do ,just this part is so helpful to test the syncing part ,The bandwidth limits of the pc sound card or built in audio device are its only limit's but if you take that into account its a great tool for those making monitors needing a video to display even out side a good display range its better than what we had before which was just NBTV standards .

As you may have saw i was experimenting very low frame rate on this CRT monitor to test a higher line rate 240 line 2 frames a sec just to test what the CRT can display which i couldn't at the higher frame rates so just for that a big thanks for the program !
I think i will keep that idea for the monitor as i like it the cross between NBTV and SSTV .
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: Fault finding

Postby smeezekitty » Sun Feb 28, 2021 6:27 am

Harry Dalek wrote:i have been swapping to a newer computer with HD sound device .


It turns out my ALC892 in my desktop will do up to 192KHz sample rate outpt. I have no idea if the output circuit in the sound card will actually do 96KHz of bandwidth and I haven't scoped it yet. But maybe yours can do 192KHz sample rate too.
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Re: Fault finding

Postby Harry Dalek » Sun Feb 28, 2021 8:31 am

smeezekitty wrote:
Harry Dalek wrote:i have been swapping to a newer computer with HD sound device .


It turns out my ALC892 in my desktop will do up to 192KHz sample rate outpt. I have no idea if the output circuit in the sound card will actually do 96KHz of bandwidth and I haven't scoped it yet. But maybe yours can do 192KHz sample rate too.

i have a Lenovo ideapad s145-15ast just says AMD HD audio in my manual ,and testing the sound this program to record at top settings seems to keep up to 128khz using program below ,really have to see using your program top settings against my older lap top see if there really is a difference as i can use your higher settings in freenbtv with my old toshiba and this recording program also unless the old laptop has a better sound device than i thought ,bit of a head scratcher.
https://www.passmark.com/products/soundcheck/
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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