Interesting pic !

[Phil Allison]

"Bob Parker

Phil Allison


Google might be my friend, but searching for technical info on the
actual Dolby 701/702 digital track readers and their CCD sensors ain't
easy! I found heaps of info about how to install them into various models
of projectors and connect and align them, though.
Anyhow, http://www.hps4000.com/pages/digital/dolby_sr_d_digital.pdf
says...

The data block is read by a 512 element charged coupled device (CCD),
which is, in essence, a television camera. The output of the CCD is an
analog video "picture" of the spots on the film. This is converted into
the digital video domain at a rate which tracks the speed of the film.
This video data is scanned for synchronization information and to
determine where the four corners of the data block are located. If two of
the corners are known, the position of the entire block is known and the
proper location of the data bits is known. Determining the whether or not
a real data spot exists and preventing false data from entering the
process is best understood by imagining a piece of window screen being
placed directly over the data block. The corner bits verify the proper
Position for the screen. Looking at the "screen", one sees in the small
square openings exactly where the spots should be. Using a digital version
of such a screen, the data spots are identified and then sent to a
"thresholding" stage for further enhancement. Based on the average density
of the spots, a threshold value is determined, above which the spot is
recognized as a "1" and below which, a "0". This stage reduces the
possibility that a scratch could be mistaken for actual data and
establishes what, on the film, is a spot and what is not.

I'm not sure if that clarifies anything or not.

** Well, it sure as hell clarifies it ain't a line scanner - it's a camera.





........ Phil

 

[Bob Parker]

** Well, it sure as hell clarifies it ain't a line scanner - it's a camera.



....... Phil

I'm keeping an open mind until I get more info. I can't see how a
CCD with only 512 photodetectors arranged as a square array could read a
60 x 60 dot array. It don't add up.
To a journo, anything with a lens which responds to light is "a
camera". ;-)

Bob

 

[Phil Allison]

If the sensor is a 512 element CCD then this would only be compatible
with the linear sensor hypothesis as put forward by Jansen

** Wiki I quoted says ( in part) :


" A CCD scanner in the projector picks up a scanned video image of this
area, and a processor correlates the image area and extracts the digital
data as an AC-3 bitstream. These data are finally decoded into a 5.1 channel
audio source. "


Pays one not to rely on fallible memory .......




........ Phil

 

[[email protected]]

Google might be my friend, but searching for technical info on the
actual Dolby 701/702 digital track readers and their CCD sensors ain't
easy! I found heaps of info about how to install them into various
models of projectors and connect and align them, though.
Anyhow, http://www.hps4000.com/pages/digital/dolby_sr_d_digital.pdf
says...

The data block is read by a 512 element charged coupled device (CCD),
which is, in essence, a television camera. The output of the CCD is an
analog video "picture" of the spots on the film. This is converted into
the digital video domain at a rate which tracks the speed of the film.
This video data is scanned for synchronization information and to
determine where the four corners of the data block are located. If two
of the corners are known, the position of the entire block is known and
the proper location of the data bits is known. Determining the whether
or not a real data spot exists and preventing false data from entering
the process is best understood by imagining a piece of window screen
being placed directly over the data block. The corner bits verify the
proper Position for the screen. Looking at the "screen", one sees in the
small square openings exactly where the spots should be. Using a digital
version of such a screen, the data spots are identified and then sent to
a "thresholding" stage for further enhancement. Based on the average
density of the spots, a threshold value is determined, above which the
spot is recognized as a "1" and below which, a "0". This stage reduces
the possibility that a scratch could be mistaken for actual data and
establishes what, on the film, is a spot and what is not.

I'm not sure if that clarfies anything or not.

Bob

If the sensor is a 512 element CCD then this would only be compatible
with the linear sensor hypothesis as put forward by Jansen

 

[Phil Allison]

"pjk"
"Phil Allison"

I searche frepatents online for "dolby sound digital projector" and
found this patent which would seem to support your view that the CCD
was two dimensional. Also searching google 1992 and CCD confirms CCD
od the order of 512K pixel were readily available at that time which
is clearly sufficient.

** Hmmm - so someone used the old " drop of the K " trick to
bamboozle everyone ??

United States Patent 5710752
http://www.freepatentsonline.com/5710752.html
Abstract: An apparatus recovers audio information from analog
and digital motion picture film soundtracks using a single optical
sensor that senses across the widths of both soundtracks. Symbols
representing audio information in the digital soundtrack are encoded
in two dimensions and are recovered by oversampling the symbols in two
dimensions. The two-dimensional encoding of digital information can be
used with a variety of recording media; however, in one embodiment,
the symbols are carried on motion picture film between the sprocket
holes.

** Hah - two dimensions IS better than one.

Flat Earthers, take heart.....




....... Phil

 

[pjk]

** Wiki I quoted says ( in part) :


" A CCD scanner in the projector picks up a scanned video image of this
area, and a processor correlates the image area and extracts the digital
data as an AC-3 bitstream. These data are finally decoded into a 5.1 channel
audio source. "


Pays one not to rely on fallible memory .......




....... Phil

Phil
I searche frepatents online for "dolby sound digital projector" and
found this patent which would seem to support your view that the CCD
was two dimensional. Also searching google 1992 and CCD confirms CCD
od the order of 512K pixel were readily available at that time which
is clearly sufficient.

United States Patent 5710752
http://www.freepatentsonline.com/5710752.html
Abstract: An apparatus recovers audio information from analog
and digital motion picture film soundtracks using a single optical
sensor that senses across the widths of both soundtracks. Symbols
representing audio information in the digital soundtrack are encoded
in two dimensions and are recovered by oversampling the symbols in two
dimensions. The two-dimensional encoding of digital information can be
used with a variety of recording media; however, in one embodiment,
the symbols are carried on motion picture film between the sprocket
holes.

 

[Bob Parker]

** Hmmm - so someone used the old " drop of the K " trick to
bamboozle everyone ??

That would explain everything!

Bob

 

[Bob Parker]

Just do a Google Groups search on "Phil Allison+Tourette's Syndrome". You'd
be surprised what you come up with.

Your search - "Phil Allison+Tourette's Syndrome" - did not match any
documents.

 

[Alan Rutlidge]

wow, whered that come from Phil?

Do you suffer from tourettes or something?

Just do a Google Groups search on "Phil Allison+Tourette's Syndrome". You'd
be surprised what you come up with.

 

[Alan Rutlidge]

Your search - "Phil Allison+Tourette's Syndrome" - did not match any
documents.

Sure you tried Google under Groups?
My search got 152 results.
http://groups.google.com.au/groups?q=Phil+Allison+Tourette's+Syndrome&hl=en&ie=UTF-8&oe=UTF-8&

 

[TT]

in message
:
::
: Sure you tried Google under Groups?
: My search got 152 results.
:
http://groups.google.com.au/groups?q=Phil+Allison+Tourette's+Syndrome&hl=en&ie=UTF-8&oe=UTF-8&
:
Yep, so did mine.

BTW *any* Google search for PA's name and the any word like
"autistic" or "bipolar" turns up some interesting posts.
But then if you want a really long list of reading material
try the "F" word or the "C" word.

Cheers TT

 

[L.A.T.]

in message
:
::
: Sure you tried Google under Groups?
: My search got 152 results.
:
http://groups.google.com.au/groups?q=Phil+Allison+Tourette's+Syndrome&hl=en&ie=UTF-8&oe=UTF-8&
:
Yep, so did mine.

BTW *any* Google search for PA's name and the any word like
"autistic" or "bipolar" turns up some interesting posts.
But then if you want a really long list of reading material
try the "F" word or the "C" word.

Cheers TT

If you have the time for any of the above, perhaps time is hanging heavily
on your hands.
You could do good deeds, visit the sick, make wooden toys for poor
children.

 

[Phil Allison]

"ER"


** **** OFF -

you illiterate, Bloody MORON !!!





....... Phil

 

[jasen]

I'm keeping an open mind until I get more info. I can't see how a
CCD with only 512 photodetectors arranged as a square array could read a
60 x 60 dot array. It don't add up.
To a journo, anything with a lens which responds to light is "a
camera". ;-)

yeah, I reckon it's something like this:

http://www.fairchildimaging.com/main/documents/CCD153ADataSheetRevA.pdf

trying to take still images of moving film seems tricky.

Bye.
Jasen

 

[Alan Rutlidge]

If you have the time for any of the above, perhaps time is hanging heavily
on your hands.
You could do good deeds, visit the sick, make wooden toys for poor
children.

Actually TT and I are both working up to self funded early retirement.
Works for me.

 

[Bob Parker]

yeah, I reckon it's something like this:

http://www.fairchildimaging.com/main/documents/CCD153ADataSheetRevA.pdf

trying to take still images of moving film seems tricky.

Bye.
Jasen

Thanks for the info.
Fax machines don't take still photos of the moving document then
electronically scan them... they just digitize a single one-pixel-wide
strip as the document goes past. The same with document scanners except
that the sensor is normally the moving part.
I can't see why it would be any different with rows of optical data
bits on a moving film, letting the linear motion of the film do the
'scanning'.

 

[Phil Allison]

"Bob Parker"

Fax machines don't take still photos of the moving document then
electronically scan them... they just digitize a single one-pixel-wide
strip as the document goes past. The same with document scanners except
that the sensor is normally the moving part.
I can't see why it would be any different with rows of optical data bits
on a moving film, letting the linear motion of the film do the 'scanning'.

** Only thing is, the required resolution is approx 2000 lines per inch
while the linear scanning speed, at 18 inches per second, is about 100 times
faster than a normal scanner.

Be very nice if desktop scanners could do that.




........ Phil

 

[Bob Parker]

** Only thing is, the required resolution is approx 2000 lines per inch
while the linear scanning speed, at 18 inches per second, is about 100 times
faster than a normal scanner.

Be very nice if desktop scanners could do that.


....... Phil

I thought I was the only one here who stays up this late/early.

Yeah, it would save a lot of time if your average flat-bed scanner
could manage that!

Assuming that the figures we've been taking to be correct really
are, it translates to about 36,000 rows of data/second going past the
reader.
That means a linear sensing array like that Fairchild one and its
associated electronics would have about 27us to digitize each row. The
frequency response of that sensor is quoted at 20MHz, which would seem
to indicate it could easily respond to optical data going past at that
speed.
The reader assembly's a precise-looking thing. It shouldn't be too
hard to make optics which can focus 2,000 lines/inch data bits onto a
linear CCD array, should it? Your average digital camera's optics are
sharply focussing an entire scene onto a sensor which is typically only
about 6mm square.
I'm not saying that I know for sure how the system works, but the
linear sensor array idea looks practical as far as I can see.


Bob

 

[Bob Parker]

I've just uploaded a pair of relevant images to my web space.
http://members.ozemail.com.au/~bobpar/ccd-assy.gif was taken from the
exploded diagram of the Dolby 701 digital track reader. Note that the
gasket which sits between the optics on the right and the electronics
board on the left has a pretty narrow rectangular slot cut into it.
http://members.ozemail.com.au/~bobpar/512-ccd.gif is the Fairchild
512 bit linear image sensor. It might just be coincidence, but it has 24
pins, and the Dolby 701 electronics board has 24 holes for its sensor.


Bob

 

[jasen]

"Bob Parker"




** Only thing is, the required resolution is approx 2000 lines per inch
while the linear scanning speed, at 18 inches per second, is about 100 times
faster than a normal scanner.

that chip that google found me (Fairchild CCD153A) can do a 20 MHz data rate,
that comes out as about 39000 lines per second (if I'm reading the data sheet
correctly), sufficient I think.

Bye.
Jasen