Alt-BEAM Archive
Message #09067
To: 'beam@sgiblab.sgi.com' beam@sgiblab.sgi.com
From: Wilf Rigter Wilf.Rigter@powertech.bc.ca
Date: Wednesday, 12 January 2000 1:13
Subject: BEAM VIDEO was RE: Solar Powered Camera's
>BEAM circuits are very similar to the older analog type video technology
>still used in simple B/W TVs and 20 years ago all televisions used analog
>beamlike circuits for decoding video signal.
>
>So it's not surprising that it is fairly simple to use BEAM circuit blocks
>to convert video into digital or analog signal suitable for interfacing
with
>other beam circuits. In the example suggested by Dennison below, The video
>signal is converted into a 2x2 matrix which corresponds to the average
>light level of a quadrant of a video frame. The attached block diagram
shows
>the general concept of such BEAM video decoder.
>
>A composite video signal (ie a sugar cube camera output) is processed by a
>sync separator to produce Horizontal and Vertical sync pulses as well as a
>DC restored video signal. This circuit requires some 2N3904s and a few
>passive components. The H and V sync signals each trigger a Hsync Nv and
>Vsync Nv (74HC14) respectively which are adjusted to time out at a point
>corresponding to the horizontal and vertical midpoint of the screen. The
>signals are connected to one half of a 74HC139 (Z bridge) which generates 4
>control signals corresponding to each screen quadrant. These 4 Q signals
are
>used with four 4066 analog gates to route the video signal to one of 4 Nu
>(74HC14). The analog voltage on each Nu cap corresponds to the average
video
>signal of that quadrant This can be used to "influence" a central pattern
>generator like a microcore. A digital signal can be generated with a one
bit
>A/D converter also know as a comparator or Schmitt trigger. If the video
>level on the Nu cap is above the trigger level of the comparator, a LED
>turns on. A bright light moving from one quadrant to the next, will turn on
>the corresponding LEDs indicating the relative position of the light.
>
>This concept can be scaled up to a low resolution "gray scale" (or red
>scale) monitor (ie 8 by 8 LED matrix) which can also be easily made with a
V
>and H chains of 8Nvs each buffered with HC240 LED drivers which can drive
>64 LEDs in real time. The video signal is "sliced" by a comparator the
>output of which drives the HC240 tristate enable lines. No Nu stages are
>needed to measure the average video since your eyes will do a visual
>integration of the LED light level. Any old video signals can be used for
>experimenting with this concept including a camcorder or VCR video output.
>
>regards
>
>wilf
>
> <> <>
>
>
>> -----Original Message-----
>> From: Dennison Bertram [SMTP:dibst11+@pitt.edu]
>> Sent: Tuesday, January 11, 2000 10:07 AM
>> To: beam@sgiblab.sgi.com
>> Subject: Solar Powered Camera's
>>
>> Hey, look at:
>>
>> http://www.mpja.com/allpict.asp?dept=125
>>
>> You should see the "sugar Cube" Camera. It runs on 5v 10ma, a power level
>> easilly provided by a solarcell. Any ideas? Possibly, Hey Wilf! think you
>> could come up with something to interpret video signals? What would be
>> MOST
>> interesting is if we could find away to interpret the general LIGHT level
>> of
>> a quadrant of the cameras vision. IE LEFT, RIGHT, UP, DOWN. That way we
>> could then use cameras as light level inputs to say, a head. I'm thinking
>> that analog wise, this might be a little difficult.
>>
>> dennison
>
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