how I can connect 89c51serial port to telephone lineto send data?

dear all, I try to send vedio from cctv via telephone line I connect the cctv camera output to ADC and the output of the ADC to Atmel 89c51 micocontroller to send the data serial but I want to connect the output of the atmel89c51 to the telephone line

please help?

what the next step

best regards yar

On a sunny day (27 May 2007 10:06:28 -0700) it happened "st snipped-for-privacy@yahoo.com" wrote in :

You need to understand bandwidth. If you digitize say 640x480 at 25 fps with full RGB 24 bits, then you need 640 x 480 x 25 x 24 = 184 320 000 bits per second, or 184 Mbits per second. A V90 modem (best you can find likely) is good for only 56 kbps IIRC.

This is why 'compression' (not lossless, but like mpeg2, or better here mpeg4 H264) is used to reduce the bitrate. But even with a comopression factor of 50 (really high) you would need

3 686 400 bits per second, so 3.7 Mbits / second so now way. Using YUV (reducing detail for color) actually brings it down to 1Mbits second.

This is indeed what we see for example for DivX 640x480 @ 25 fps. But your V90 modem cannot do that.

If you go 360x240 about a quarter (screen surface), still no fun. Reduce the frames per second to 5, and bingo.

So 320x240 @ 5fps mpeg4, you need to implement a mpeg4 / H264 encoder, get a V90 modem....

Did I say: Forget it? H264 realtime takes a lot of resources, you need a special chip, or do it in software, say a 250 MHz processor in your case, small Linux system perhaps, or do it in FPGA.

Hoi.

You will not be able to send real time images from a cctv over a telephone line.

You could add a frame store, after your ADC, for example

and use a modem

to send one frame at a time, it will be quite slow

martin

Nice one. CCTV is actually quite often a frame every few seconds. But I suspect that isn't what OP was looking for.

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By "telephone line" do you mean just the wires or is there some normal phone hardware involved. Do you have DSL?

I assume you are digitizing just a black and white signal and are sampling at a speed less than full speed already. Now you need to figure out exactly how much data you absolutely must send. Even with an 8051, the video can be compressed somewhat. You usually will want the numbers you send to be from pixels next to each other. If you do this then you can send the rate of change in the brightness.

SSTV :) you can sent some very clear B&W images in 36 secs in a band space of

1 Khz ..2.3Khz..

Color in 72 secs. these are in a 320x256

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