120 line conversion

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120 line conversion

Postby Harry Dalek » Sat Jun 24, 2017 2:04 pm

120 line .....almost ! getting there...... with changing the line sawtooth capacitor i got 3050 hz almost there think i need to reduce a resistor on the line side as advice from steve a few posts back for 60 line ran out of time today i will work some more on it tomorrow
The line frequency is 3khz and frame is 25hz .
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IMG_3070.JPG
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Last edited by Harry Dalek on Sat Jun 24, 2017 6:52 pm, edited 4 times in total.
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: 120 line conversion

Postby Harry Dalek » Sat Jun 24, 2017 6:32 pm

I was a bit rushed this morning but i wanted to tackle 120 lines today pleased i got something up .
i am very close to syncing what is needed is a line frequency of 3khz .. what i ended up doing so far i had to replace C721 47n with a 4.7n that with adjustining the pot across R704 frame frequncey to 25hz ......the line frequency is 3050hz ...i really need to adjust R724 i think to get the line frequency into sync ,this i will try tomorrow .
I forgot to mention this should be a horizontal scanned picture i will work on that when i see a image side ways :wink:

youtu.be/zA2lg6h7vg4
Last edited by Harry Dalek on Sun Jun 25, 2017 2:43 pm, edited 2 times in total.
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: 120 line conversion

Postby Harry Dalek » Sun Jun 25, 2017 2:22 pm

I managed to get some images up ....ended up having to make the line and frame saw tooth oscillators variable setting the frame to 25 hz and the line first seeing 2 images at 1,8 khz single image at about 3.6 khz .
3khz line and 25hz frames 120 lines 3.6khz 25 hz 144 lines not sure why i am having problems with just 3khz only really getting a image at around 3600hz
Now not really what i was expecting perhaps i am getting the over lapping line effect as Steve warned me about not sure .
I was trying test cards and was not really getting viewable image so i still have a ways to go here but some things worked out to show here today .
Images have a low contrast pretty much set here maximum or it would be very washed out looking .
The raster looks fine but when displaying images Quality is much less than should be expected more head scratching

youtu.be/9hBi1rjsalA BATMAN SAYS NO


youtu.be/LmPqJD4A89A ME
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Blank 120 line raster no video
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horizontal scan turned me side ways now thats better
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Last edited by Harry Dalek on Sun Jun 25, 2017 6:48 pm, edited 1 time in total.
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: 120 line conversion

Postby Harry Dalek » Sun Jun 25, 2017 4:44 pm

Been looking rereading Steve O posting on 120 and 180 line viewing on he's Argus build very inspirational for me .
viewtopic.php?f=10&t=1876&hilit=405+line

Edit
Reading these posts there were some systems only used for a short time
I suppose with electronic television with in limits you could work out your own system starting off after 60 lne or 64 line due to that lack of video signal for testing using your scope and the monitors sawtooth a slide and some sort of senor on a head amp make your own old school video signal closed system but at least you can view something on testing .
30 375hz 12.5
60 750hz 12.5
80 line 1khz 12.5 or
100 line 1.25khz 12.5
120 line 1.5khz 12.5
or
24 300hz 12.5
32 400hz 12.5
48 600hz 12.5
64 800hz 12.5
96 1.2khz 12.5
128 1.6khz 12.5
BTW when does NBTV stop and MBTV start ? 100 line ?
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grey_scale.zip
120 line wav video file
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120 line test card
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120FSCPlayer.zip
120 line player thank you gary
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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: 120 line conversion

Postby Steve Anderson » Sun Jun 25, 2017 10:15 pm

Harry Dalek wrote:BTW when does NBTV stop and MBTV start ? 100 line ?

Jeremy Jago takes the attitude that anything less than 405 is suitable for the newsletter, which would include 240-lines. There was a short 240-line item a few years ago. Even SSTV is OK in small doses, again a SSTV item was in a recent newsletter.

Otherwise it's an individuals perception I guess. Some might say less than 10kHz bandwidth, others might say that it can be contained in a wave file (96kHz bandwidth, 192kHz sample rate), others possibly more.

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Re: 120 line conversion

Postby Harry Dalek » Mon Jun 26, 2017 6:49 pm

Steve Anderson wrote:Jeremy Jago takes the attitude that anything less than 405 is suitable for the newsletter, which would include 240-lines. There was a short 240-line item a few years ago. Even SSTV is OK in small doses, again a SSTV item was in a recent newsletter.


OH thats interesting ,so something around 300 lines is still NBTV ! i was going to put NBTV on my Test card but was not sure if this was right .

Otherwise it's an individuals perception I guess. Some might say less than 10kHz bandwidth, others might say that it can be contained in a wave file (96kHz bandwidth, 192kHz sample rate), others possibly more.

Steve A.


Perhaps we worry to much about the recording side of it is it recordable as a wav file ....,theres always a way to display and take a picture it also is a bit harder for the mechanical side unless its sstv :wink:
CRT displays i can't see the problem stopping us,i can only think lack of experimenting well much any way is the lack of a testing video signal .
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: 120 line conversion

Postby Klaas Robers » Mon Jun 26, 2017 7:45 pm

I think Steve is right. Narrow Band will say narrow bandwidth. That is the bandwidth of the video signal.
625 lines 25 Hz = 5 MHz
525 lines 30 Hz = 4 MHz
405 lines 25 Hz = 3 MHz
120 lines 25 Hz = 275 kHz
60 lines 12,5 Hz = 34 kHz
32 lines 12,5 Hz = 10 kHz (NBTVA-standard)
120 lines 1/7.2 Hz = 1 kHz (SSTV-standard)

Now is the question: What is narrow bandwidth?
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Re: 120 line conversion

Postby Harry Dalek » Mon Jun 26, 2017 8:23 pm

Klaas Robers wrote:I think Steve is right. Narrow Band will say narrow bandwidth. That is the bandwidth of the video signal.
625 lines 25 Hz = 5 MHz
525 lines 30 Hz = 4 MHz
405 lines 25 Hz = 3 MHz
120 lines 25 Hz = 275 kHz
60 lines 12,5 Hz = 34 kHz
32 lines 12,5 Hz = 10 kHz (NBTVA-standard)
120 lines 1/7.2 Hz = 1 kHz (SSTV-standard)

Now is the question: What is narrow bandwidth?


Its a wonder it has not been really worked out yet i was thinking at first what ever is recordable in the audio range of a analog or digital recording device .
Perhaps it should just be looked at as its analog original signal unchanged in any way .
Medium bandwidth Television i would think is out of Audio recording range and up to 1 MHZ we need a judge ! Judge Andrew ~!
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: 120 line conversion

Postby Steve Anderson » Mon Jun 26, 2017 9:03 pm

Of note is the fact that with a standard VHS/Betamax VCR if the field or frame rate is 50Hz (60Hz US or a multi-standard machine) any analogue format can be recorded. 405 monochrome recordings on a VCR are very good as the 405 sinal only requires 3MHz and the VCR delivers around 2MHz, 66%. For 625 that drops to 40% of the luminance signal, we'll ignore colour here.

So MDTV (whatever standard), 120/50 or any not far from those sort of bandwidths will be fine. You don't need the complex vertical sync signal, a single broad pulse of around 160us per frame/field will do.

The question is - who still has an operational VHS/Betamax VCR? Are the tapes you still have any good?

I have a VHS machine wrapped up in a plastic bag that hasn't been switched on in a decade at least. I can imagine perished belts, pinch-rollers and dry electrolytics etc.

Steve A.
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Re: 120 line conversion

Postby Harry Dalek » Mon Jun 26, 2017 9:28 pm

Since i was chatting about a video signal for a future higher rate display i forgot i do have some images on file for some nice Flying spot scanners ,would be nice to have a good read of the Dyna-Scan Flying Spot Video Generator,1956 manual ,i see it on the desk i want to read it !
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Last edited by Harry Dalek on Mon Jun 26, 2017 10:27 pm, edited 1 time in total.
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: 120 line conversion

Postby Harry Dalek » Mon Jun 26, 2017 9:49 pm

Steve Anderson wrote:Of note is the fact that with a standard VHS/Betamax VCR if the field or frame rate is 50Hz (60Hz US or a multi-standard machine) any analogue format can be recorded. 405 monochrome recordings on a VCR are very good as the 405 sinal only requires 3MHz and the VCR delivers around 2MHz, 66%. For 625 that drops to 40% of the luminance signal, we'll ignore colour here.


I recall apart from the speed difference problem NTSC tapes played on VHS i could check i still have every one or having multi system VCR then pal recorded on NTSC played back in B/w as i recall .\
I always wondered about 405 ! if it could be recorded on a 625 line vcr what could be recorded on say vhs from the lower line rate systems Steve ?

So MDTV (whatever standard), 120/50 or any not far from those sort of bandwidths will be fine. You don't need the complex vertical sync signal, a single broad pulse of around 160us per frame/field will do.


Wow thats thats interesting sounds like a future experiment in the making !
The question is - who still has an operational VHS/Betamax VCR? Are the tapes you still have any good?


Well i do i have umatic beta vhs and super vhs ! boxes of tapes and i do mean big boxes ! hoarder i am .

I have a VHS machine wrapped up in a plastic bag that hasn't been switched on in a decade at least. I can imagine perished belts, pinch-rollers and dry electrolytics etc.

Steve A.
[/quote]

The beta has not been used for 5 years i would say think i have 2 of those ! a few vhs a a play super vhs and a recorder super vhs umatic i only have one worked last year fine .
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: 120 line conversion

Postby Andrew Davie » Mon Jun 26, 2017 10:15 pm

Harry Dalek wrote:Its a wonder it has not been really worked out yet i was thinking at first what ever is recordable in the audio range of a analog or digital recording device .
Perhaps it should just be looked at as its analog original signal unchanged in any way .
Medium bandwidth Television i would think is out of Audio recording range and up to 1 MHZ we need a judge ! Judge Andrew ~!



Anything is welcome on the forum - I'm not a bandwidth snob ;)
Pretty much anything is welcome provided it's in the correct part of the forum.
Far be it for me to judge.


We have these same sorts of discussions in vintage game forums; where the Atari 2600 was originally for up to 4KB of ROM and 128 bytes of RAM, now-a-days people have added coprocessors feeding data to the cartridge data lines on-the-fly (called bus stuffing) at very high frequencies, effectively increasing the capability of the machine way beyond what was originally possible. With 32 bit ARM processors also available for number crunching, there's a huge divide over what is allowable and what's not. It's not a level playing field if you're comparing these enhanced games against the hardware of the '70s. So in my view ALL are perfectly valid and it's up to the individual to decide where they draw the line. For me I'm happy to allow extra RAM, and esoteric bank-switching schemes for extra ROM, but I'm not willing to entertain external CPUs doing all the hard work. I'm not saying that people who do allow those things I don't are wrong - we just have different interests.

So saying, and back to the NBTV question - I think it's something that each of us will approach and define in our own way. For example, my Arduino televisor is 19200bps which is quite low. I like that I am packing sound and vision into two 8-bit channels at a low rate, akin to something radio would provide back in the day. But I think this is one end of the NBTV spectrum. I really don't care to define what the upper end should be!
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Re: 120 line conversion

Postby Steve Anderson » Mon Jun 26, 2017 10:17 pm

Nor I. Agreed.

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Re: 120 line conversion

Postby Dave Moll » Tue Jun 27, 2017 4:54 pm

Steve Anderson wrote:The question is - who still has an operational VHS/Betamax VCR? Are the tapes you still have any good?


I have a combined VHS/DVD recorder (recently acquired second-hand) which is in full working order - I recently successfully copied some VHS tapes to DVD.

As to using VHS for recording formats other than the 625-line (or whatever) for which it is designed, my understanding is that it only works successfully on earlier machines that don't attempt clever post-processing of the signal. This is, however, only what I have heard from others. I have never tried recording 405-line output (such as from my standards converter) - maybe I should give it a go some time.
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Re: 120 line conversion

Postby Harry Dalek » Tue Jun 27, 2017 5:13 pm

No worries Andrew Steve only makes the forum more interesting ! I was just perplexed as to what is and isn't Medium and narrow band Television if its in the eye of the beholder i will have to go with my instincts and google Gary :shock:


youtu.be/Sa04GhS99pw
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