Fresh challenges?

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Fresh challenges?

Postby AncientBrit » Thu May 17, 2007 11:27 pm

Baird seems to have covered most topics in his lifetime and given us a template for future experimenting.

I can think of only one topic that he may not have covered, that of bandwidth compression.

Any suggestions for other novel aspects to be explored with NBTV?

Regards,

GL
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Re: Fresh challenges?

Postby Viewmaster » Fri May 18, 2007 12:07 am

AncientBrit wrote:Any suggestions for other novel aspects to be explored with NBTV?
GL


In car NBTV?
Run another belt from the car's fan belt to the Nipkow disc! :shock:
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Re: Fresh challenges?

Postby gary » Fri May 18, 2007 1:41 am

Viewmaster wrote:
AncientBrit wrote:Any suggestions for other novel aspects to be explored with NBTV?
GL


In car NBTV?
Run another belt from the car's fan belt to the Nipkow disc! :shock:
Albert.


I think that suggestion belongs in the 'non-electrical' thread. ;-)
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Postby Viewmaster » Fri May 18, 2007 6:32 pm

How about a wrist watch NBTV?...there's a mech/electronic challenge!

Nipkow disc about 40mm dia with viewing size of about
4.5mm x 3mm wide....holes would be about .1mm dia !!
Maybe a dedicated IC to do everything!

The watch dial would be a very high power lens and to see the image, one held it up to one's eye, like a watchmakers lens.
Wind it up just like a watch and it runs!

Next step after that........... built in colour! :shock:
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Postby Stephen » Fri May 18, 2007 10:56 pm

Viewmaster wrote:How about a wrist watch NBTV?...there's a mech/electronic challenge!

Nipkow disc about 40mm dia with viewing size of about
4.5mm x 3mm wide....holes would be about .1mm dia !!
Maybe a dedicated IC to do everything!

The watch dial would be a very high power lens and to see the image, one held it up to one's eye, like a watchmakers lens.
Wind it up just like a watch and it runs!

Next step after that........... built in colour! :shock:
Albert.
I have got it...the display could show the date!
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We neeed Phonovision!

Postby Stephen » Fri May 18, 2007 11:31 pm

What the public is clamouring for is Phonovision! Perhaps we can bring the player shown in British Patent 324,049 to life. It is archived in the "Patents and Articles" section of the forum.
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More Phonovision.

Postby Stephen » Sat May 19, 2007 12:01 am

Also see the earlier Phonovision patent, British Patent 289,104 in the "Patents and Articles" section. Mr. Baird shows a two-groove embodiment for video and audio in Figures 2 and 3, with vertical modulation for vertical and lateral modulation for audio. He also describes an alternate embodiment in the specification, on page 2, column 1, lines 35 through 41, wherein he says a single groove may have a combination of vertical and lateral modulation to provide both sight and sound! He anticipated Mr. Blumlein's efforts at dual channel disc recording by about six years.
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Postby DrZarkov » Sat May 19, 2007 12:08 am

Phonovision is nowadays just a question of money. There are recording-sets for common LPs available. They cost about 2,500 EUR. The quality of a LP is as good as a CD-rom (of not better because there is no compression).

There are recording systems for 78th, too. Even more expensive...

Playback is no problem nowadays, just take a common record-player with 78 rpm, a suitable needle, that's it.

I think a kind of pocket NBTV monitor would be more interesting. I saw some years ago at the "Cebit", a computer fair in Hannover, a "modern" system, made for pilots: there is only one line of LEDs in the window of the plane, the pilot has in his helmet a kind of rotating mirror-drum, that creates in his glasses a whole picture. To me it seemed not very revolutionary new, but it's funny that they want to use mechanical TV for working in a plane to safe space on the dashboard.

Let us combine now Baird with Sinclair to create a micro NBTV monitor :lol:
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Postby DrZarkov » Sat May 19, 2007 12:23 am

A real challenge: Many years ago, when I saw old computer memory using magnetized iron rings I've had an idea how to make a display: A frame with 48 horizontal wires, on each there are 32 magnetized iron rings. The northpole-side of each ring is painted white, the south pole black. On the back side of the frame there are electro-magnets, connected to a video controller. The rings will turn depending to the polarity of the elctromagnet behind and show the black or the white side. The advantage is no flickering at all and no problems with light. The problem is the controller (that's why I never built such a device) and if the rings will react fast enough to show moving pictures.

I
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Flicker reduction.

Postby Stephen » Sat May 19, 2007 1:26 am

DrZarkov wrote:The rings will turn depending to the polarity of the elctromagnet behind and show the black or the white side. The advantage is no flickering at all and no problems with light.
This is a nice idea, Volker. It is sort of an electromagnetic version of a micromirror array for a DLP.

Thinking of flicker-free displays, John Logie Baird had a number of concepts that used phosphorescent screens. One that has always intrigued me is in his British Patent 325,527, filed 21 September 1928. Instead of using apertures, the scanning disc uses a spiral arrangement of electrical discharge points, as shown in Figures 2 and 3. Therefore there is one electrical discharge point for each line. The video signal modulates the intensity of the electrical discharge. The phosphorescent screen lights in response to the level of the discharge and the glow time of the phosphor may reduce or eliminate flicker.

This patent is in the "Patent and Articles" section of the forum.
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Postby DrZarkov » Sat May 19, 2007 2:25 am

..but then you can use as good a CRT, I think there had been never such a monitor built.
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Another challenge.

Postby Stephen » Sat May 19, 2007 3:21 am

DrZarkov wrote:..but then you can use as good a CRT, I think there had been never such a monitor built.
That is true, Volker. However, the CRT solution is not really a fresh challenge, as many have done just this. Besides, without turning to a PC, a CRT monitor would require building sawtooth generators for vertical and lateral deflection, synchronisation and blanking circuitry and the CRT power supply.

It is also a challenge to try to implement 1928 technology of this type. The only thing different about the electrical discharge scanning disc should be the driver. I think that the sort of driver for ionic or electrostatic loudspeakers, or perhaps a modification of such a driver, might suffice.

Conceptually a display with a scanning disc of this type might be able to exhibit a very high brighness level. All of the electrical discharge concentrates into illuminating a single pixel at a time so that there is no wasted energy.
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Postby Klaas Robers » Sat May 19, 2007 6:11 am

Phonovision, read the book of Don McLean. The problem was that Baird had just 5 frames per second, which is too slow to display a picture.

Then the integrating effects of the eye disappears.

To get that he had already several "picture spirals" on one revolution. Look at the drawings, try to calculate the size of the holes and you will see that they become too small to make.

He also tried to run the record faster, but the window in which 78 rpm records are playable was too narrow.

I think that that is the reason that he stopped work on Phonovision....
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Phonovision.

Postby Stephen » Sat May 19, 2007 7:05 am

That is true about the 5 fps with Baird's phonovision experiments, Klaas. The recording equipment seems to have been unusually poor and the frequency response would not have been sufficient to have supported 12.5 fps. According to the estimated frequency response graph of the system as shown in Don's book at page 166 of Don's book, the system had a sharp roll-off above 1500 Hz! Yet even the early Western Electric electrical disc cutters were capable of relatively flat response out to 5 or 6 kHz, so perhaps Mr. Baird had to settle for a loudspeaker-microphone linkage between the video system and the recording system, as Don suggests.

However, the later disc recordings made by others that Don has restored were all at 12.5 fps. By 1930, radio transcription discs using hill-and-dale recording techniques, as Mr. Baird had suggested in his first Phonovision patent, were capable of capturing a 10 kHz range.

You have a good point about the aperture sizes for a ten spiral arrangement as shown in the patent. Obviously this would not be practical. An obvious modification though would have a gramophone turntable concentrically mounting above a scanning disc through a ten-to-one gear reduction to allow a scanning disc with a single spiral to rotate at 750 rpm whilst the turntable rotates in synchronisation at 75 rpm. The general appearance and operation would then be the same as shown in the patent, the only change being the addition of the reduction unit between the turntable and the scanning disc.
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Postby Klaas Robers » Sun May 20, 2007 2:51 am

The clever point was just to combine the rotation of the record and the Nipkow disc. With a separated drive as sugested this is not half that attractive. The synchronisation problem was solved by this system, although there should be a means to position the record in the best angle. You see also that Baird sugested a kind of microscope to view the Nipkow picture.

The other records were just recorded 12,5 fps BBC video. Of course that will work. 78 rpm is not that bad. But that was ment for a separate Bird Televisor. Be assured that the synchronisation problem wasn't solved at all in those days. I fear that sometimes it worked for a short period.
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