Motion Detection in NTSC Signal

This is the place for any magazine-related discussions that don't fit in any of the column discussion boards below.
Post Reply
jalbers
Posts: 18
Joined: Tue Dec 18, 2001 1:01 am
Contact:

Motion Detection in NTSC Signal

Post by jalbers » Thu Feb 13, 2003 1:09 pm

I am looking for information on how to detect motion in NTSC signal from one of those cheap 1" square cameras. Is there a cheap off the shelf chip or little black box that could look for changes in the NTSC signal? I am currently only interested in black and white. I am sure that this is not the first time this has come up. Surely someone makes a chip for this.<p>If not, could a PIC chip, burst detector, and a analog to digital converter be used to look for changes in the signal?<p>Any help would be greatly appreciated.

bodgy
Posts: 1044
Joined: Tue Dec 04, 2001 1:01 am
Location: Australia
Contact:

Re: Motion Detection in NTSC Signal

Post by bodgy » Thu Feb 13, 2003 7:33 pm

I think the easier and cheaper method would be to scrounge an PIR detector, mount it on the camera so the focal planes are similar, and use the relay contacts or similar from the PIR to trigger whatever it is you need to trigger.<p>Look in the recent archives of the Piclist someone was doing something similar to detect wild life and film it.<p>colin
On a clear disk you can seek forever.

ad5mb
Posts: 40
Joined: Sat Dec 28, 2002 1:01 am
Contact:

Re: Motion Detection in NTSC Signal

Post by ad5mb » Fri Feb 14, 2003 8:54 am

Not exactly what you're asking for, but it may be what you want:<p>http://www.gotchanow.com

User avatar
Chris Smith
Posts: 4325
Joined: Tue Dec 04, 2001 1:01 am
Location: Bieber Ca.

Re: Motion Detection in NTSC Signal

Post by Chris Smith » Fri Feb 14, 2003 12:11 pm

Yes they make them but they arent cheap.

Dean Huster
Posts: 1263
Joined: Wed Dec 05, 2001 1:01 am
Location: Harviell, MO (Poplar Bluff area)
Contact:

Re: Motion Detection in NTSC Signal

Post by Dean Huster » Fri Feb 14, 2003 2:06 pm

If the intended trigger event is something entering the field of view from "outside", you might possibly just measure the average voltage of the video and use a comparator to look for changes there. Of course, you'll have to change your reference level if room lighting periodically changes (sun setting, too).<p>"Real" systems have the power to digitize the image and compare one (odd or even) field to the next to detect changes. In that case, if you're comparing every tenth field, for instance, with the one that preceded it ten fields before, you would automatically compensate for "slower" light changes and only detect the faster movement of an object changing position.<p>Dean
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.

jalbers
Posts: 18
Joined: Tue Dec 18, 2001 1:01 am
Contact:

Re: Motion Detection in NTSC Signal

Post by jalbers » Wed Feb 19, 2003 9:53 am

This sounds interesting. How do you find the average voltage level? I have a feeling it is some type of circuit using op amps.

Post Reply

Who is online

Users browsing this forum: No registered users and 25 guests