Pixelvision 2000 Camcorder

[Harry Dalek]

Hi i came across this very different 80s camcorder never saw it and l lived in the 80s once !
http://www.youtube.com/watch?v=rGIbpMC2AAc

Very interesting recording b/w tv on a audio cassette running at high speed...i tell you i would of loved one back then ! may very well be worth a ebay search.

[Steve Anderson]

Harry,

PXL2000's do turn up on e-bay from time to time but at ridiculous prices considering they were aimed at kids, basically a toy. But there were some interesting methods employed which are covered in the attached patent.

There are more You-Tube clips as well...if you dig around...

Steve A.

[Harry Dalek]

Harry,

PXL2000's do turn up on e-bay from time to time but at ridiculous prices considering they were aimed at kids, basically a toy. But there were some interesting methods employed which are covered in the attached patent.

There are more You-Tube clips as well...if you dig around...

Steve A.

Hi Steve
Wonder if it was sold in Australia as knowing me at the time i would known ,i am sure there was nothing about it in the electronics mags i used to get at the time they mostly and more lilkly were interested in the market for those big vhs colour cameras.
I will have a read of the Patent
but i don't think there was any thing like it apart from the first gos at video recording ?
Do you know if they did another model or anyone else did any thing like this ? its a very interesting one off if so .
Yes i have seen the other utube videos seems to be a fair few of these about which must mean they were made well enough the last ...must be easier for high speed tape transporting than slow knowing all the screwed up tapes i recall happening with the sound cassette recorders.

[Lowtone]

They are expensives
I really like the idea of recording on cassette. I really love cassettes, I use them almost everyday

[Steve Anderson]

Harry,

I can't think of anything else similar to the PXL2000, it seems it was a unique product, but I'm bound to be proven wrong!

With few exceptions these sort of products never wear out, they simply rot with old age. Consumers buy them and once the novelty has worn off they get shoved under the bed and forgotten. I'm not quite like that. In the early 90s I bought a SVHS camcorder and for the first five years or so it saw a lot of use. Then the SVHS-C cassettes became virtually unobtainable. It was reluctantly shelved.

Around its tenth birthday I decided to resurrect it but it was lifeless and I sent it off to Panasonic for repair. I came back fully operational with the replaced parts in a little plastic bag. As expected it was all the perishable items, belts, pinch-roller and as expected virtually every electrolytic capacitor. It worked for another six months or so and died again. I've not bothered to get it repaired yet again.

I would guess that if one were to come across a non-operational PXL2000 that otherwise looks in good condition, i.e. not physically damaged, then with similar items attended to it should work fine.

Steve A.

[Lowtone]

I can't think of anything else similar to the PXL2000, it seems it was a unique product, but I'm bound to be proven wrong!

I remember a black and white camcorder, that was marketed like a toy, which and be plugged onto a VHS recorder.
I wanted one, but one year later we get a 8mm videorecorder

[Harry Dalek]

Harry,

I can't think of anything else similar to the PXL2000, it seems it was a unique product, but I'm bound to be proven wrong!

With few exceptions these sort of products never wear out, they simply rot with old age. Consumers buy them and once the novelty has worn off they get shoved under the bed and forgotten. I'm not quite like that. In the early 90s I bought a SVHS camcorder and for the first five years or so it saw a lot of use. Then the SVHS-C cassettes became virtually unobtainable. It was reluctantly shelved.

Around its tenth birthday I decided to resurrect it but it was lifeless and I sent it off to Panasonic for repair. I came back fully operational with the replaced parts in a little plastic bag. As expected it was all the perishable items, belts, pinch-roller and as expected virtually every electrolytic capacitor. It worked for another six months or so and died again. I've not bothered to get it repaired yet again.

I would guess that if one were to come across a non-operational PXL2000 that otherwise looks in good condition, i.e. not physically damaged, then with similar items attended to it should work fine.

Steve A.

HI steve

a little while back i came across another version of that cassette camcorder ,i forgot where i found it but it was about the same and i think a rip off via another company .

i just had a look on ebay and one was being sold for 300 US dollars yakes ! think i would rather try making my own at that price .

Yes we are the same vhs C then onto the cassette sized digital tape then on to the mini dvd and now onto a sd card HD one and they all end up in a box somewhere .

Would be an interesting project to try and record 625 line on a audio cassette i would be interested to see how far you could go dropping the speed so dropping the bandwidth how far you could go before the picture is i think washed out ...theres a site where tv dxers drop the bandwidth they have dropped 6mhz to 1mhz and the they think they could go to 500khz wonder if it would work the same to cassette.


I always wondered about people in the 60's who recorded from a valve tv to reel to reel tapes sort of a audio recording of a tv show ,before vcrs if any of the video signal was recorded also i know its filtered out and not much hope but as i recall on my old 60s tv at the time i could hear the change in light levels sometimes and the hum of perhaps the 50hz vertical ......thinking this on just the sync
perhaps these could be recovered via phase loop locks if they are there .
I think this might be possible as many years ago i made a circuit to detect noaa weather satellites it could lock onto the i think it was 2000hz
fax signal in the audio snow well before you could hear any thing .i used it also to play back tapes to computer for the fax images you could not do this just playing tape to computer the tape speed mucked up the freq rather nice thing it would also turn on my tape recorder to record the fax when ever the satellite passed over still have it ,nearly had it put in the local electronics mag but bit slack to write up for them but anyways !
It would be interesting to know how far you could go dropping bandwidth.

[Steve Anderson]

Audio cassettes and video...I think you only have to ask a few of the old-timers around here about that! Recording 'standard' 32-line NBTV on cassette was fraught with problems, let alone 625 conventional TV, open-reel or audio cassette!

Most problems however were concerned with the low frequency response (as far as NBTV is concerned) and this is still evident today, although with modern media it's less of a problem but it's still there.

Graham Lewis has done a lot of work in this area over the years, there's a number of postings related to this on this forum and some articles have appeared in the newsletter from time-to-time.

At the other extreme is the high frequency response, audio cassettes tapered off at less than 20kHz, even the best machines like Nakamichi's using Metal Oxide tapes could only just make that...this also required you to open your wallet....wide!

As with all analogue magnetic based media the upper frequency response is a function of recording level. For this reason the frequency response of cassettes was usually measured at -20db recording level w.r.t. to a standard-level test tape. Suppose a machine could make 20kHz at -20db, this would drop to perhaps 15-16kHz at -10db, you'd be lucky to get 10kHz at 0db level.

For speech and music the high-frequency energy content is quite low and this limited frequency response actually doesn't sound that bad. It's not perfect, but when you trade that off against the cost and convenience compared to open-reel tapes, the public make their choice. (I'm not saying that the great unwashed make the best choices though).

For decades audio cassettes realistically were the only viable recordable media open to consumers, other formats came and rapidly went, now with digital media it's very different...however I would add that in many cases it's questionable as to whether they're any better...but that's a different bun-fight.

Returning to your thoughts regarding recovery of 60s video 'embedded' within the sound recordings made off-air...I don't rate the chances of success as high. The buzz heard is probably a mixture of mains 50Hz hum, 100Hz HT ripple and vertical field/frame pulses finding their way into the audio signal. The variance of the amplitude of these would logically be related to the average picture level (light/dark) as scene changes and cuts were made.

I think that's all the information that could be recovered. As a minimum you'll need to recover sync pulses at 15.625kHz (625/50) or 10.125kHz (405/50). Any semblance of a pulse would require the odd-harmonics....47kHz (3rd), 78kHz (5th)...and so on. And that's just for a 1:1 square-wave. So, with typical bias frequencies for audio tape recorders being 50-150kHz and the limited response as a result of slow tape speed and finite head-gap width (extinction frequency) it's a perfect plot for an episode of CSI.

This all culminates in the raison d'etre of the PixelVision 2000. It's high tape speed and limited resolution made it what it is, not really something you would want to record the joyous events of your offspring's birthdays upon, but something for them to play with at that moment. It is amazing that they actually got it all to work and were able to make it into a mass produced product.

The standard VHS(C) has a luminance bandwidth of around 2MHz, the SVHS(C) system is around 4.5MHz, full broadcast 625 is 5.5-6.0Mhz depending on where you live in the PAL region...kinda redundant information these days. Dropping the bandwidth to 500kHz as these ATV'ers do will result in very soft pictures but less noise (the more you open the window, the more dirt blows in) allowing for longer contact ranges. But with a 500kHz bandwidth sync recovery is possibly the limiting factor.

Which all comes full-circle and why in many ways we are here (upon this forum). Baird and others were constrained by the transmitters, receivers and technology of the day to around 10kHz, to fit a video signal into that bandwidth is why we have 32/30 lines at 12.5fps....and it's still no easy task to record!

Steve A.

[Lowtone]

Is it a good idea ( or not ) tu use noise reduction on cassettes, like dolby or dbx ?
I got a recorder with dbx who can run the tape twice faster than the normal speed, but I didn't try to record NBTV on it yet.

To know more about cassettes I know this great forum
http://tapeheads.net/index.php


Do someone tries to record NBTV on hi-fi stereo soundtracks of VHS tapes ?

[Klaas Robers]

The real problem is that recording with HF bias and play back, as is done for audio, gives quite large phase distortion. This is fatal for NBTV video signals. There are two ways out:

1. Record not with HF-bias, but directly with a frequency modulated tone, as is done in VCR and other video tape recording. However this implies non standard recording and play back. This is only applicable to experienced electronics builders. I think the Pixelvision 2000 recorder uses this at an elevated tape speed.

2. Recording twice, the first time with time-inverted signals. In this case the phase distortion is the first time applied in negative time and the second time that is nihilated. Graham did these experiments and it looked good. But it is also rather difficult for unexperienced users.

Digital recording avoids all these problems.

[Steve Anderson]

I think the Pixelvision 2000 recorder uses this at an elevated tape speed.

Indeed it does, an eightfold increase in speed from 4.8cm/s (1.875ips) to 39cm/s (15ips) resulting in a claimed bandwidth of 100kHz. Of course playing time was proportionally reduced, a C60 cassette (30 minutes a side) became a non-standard "C7.5", all of 3 minutes 45 seconds a side! They recommended NOT using any tapes longer than C90s, I guess the very thin C120s became mangled in the transport mechanism.

The CCD was 120x90 pixels, a total of 10,800 pixels, or in modern parlance, 0.0108 mega-pixels! The video signal from the CCD after limiting and pre-emphasis modulates an VCO which records the signal onto the tape as an FM sub-carrier. A quick skim through the patent doesn't reveal what frequencies were used for the sub-carrier.

In a manner very much like the club recordings, the video signal was recorded on one track of a standard stereo pair, the audio on the other...I wonder what potential the audio track had at 15ips?

Steve A.

[Lowtone]

...I wonder what potential the audio track had at 15ips?

An audio track of 100kHz instead of 20 could record more details of the sound, and high inaudible sounds. But why they didn't use this space to record more video, or a second sound channel ?

What is the bandwith of the microphone ?

This system could be enhanced, if we use 4 or 8 tracks heads maybe
like this :
http://www.richardhess.com/tape/quarterinch_lrg.gif
http://www.richardhess.com/tape/cass_trk_lrg.gif
because there is some space beetween the tracks.
Or we could make a small track for the sound and a big one for the picture.

[LuTELLO]

My childhood PXL unfortunately didn't make it, but I was lucky enough to find one a few years ago for under $50! After replacing the belts it works somewhat, but could probably perform better if restored by someone who knows more what they're doing. My first PXL might have been what sparked my fascination with these possibilities. Dolby Digital on film was another interesting one that comes to mind.

Is it easy to make a more standard tape/cassette friendly version of NBTV? Or at least, could I get better results by taping "Chris Long Shortwave?" Gary's software doesn't seem to support this on the viewing side, so I can't test it.

I love occasionally recording images, "video," and computer data to tape, cassette, and other media for no practical reason! Problem is with my technical knowledge I'm limited to doing this with found software and as-is equipment. I have many other questions and ideas on this subject, but I'll try to read up some more before bugging people too much.

Ok, one more, anyone know if they printed any vinyl copies of the Voyager gold record? My guess is a big no! It would be interesting to decode those sstv images myself if a full copy of the disc was available.

[gary]

Gary's software doesn't seem to support this on the viewing side, so I can't test it.

Nag nag nag - OK have included support for CL SW up now on my website.

Note the only difference between this and standard NBTVA is it has a 6.25 frame rate and NO syncs.

[LuTELLO]

Gary's software doesn't seem to support this on the viewing side, so I can't test it.

Nag nag nag - OK have included support for CL SW up now on my website.

Note the only difference between this and standard NBTVA is it has a 6.25 frame rate and NO syncs.

That was a pleasant surprise! Where's your new site, the one I can find doesn't seem to have a new version.