From: Sandi McEnery [mailto:smcen...@ustech-lab.com] Sent: Wednesday, January 15, 2003 10:35 AM To: emc-p...@majordomo.ieee.org Subject: Video Cameras for EMC Test Monitoring
We are in the process of purchasing video cameras for monitoring EMC Immunity testing up to 10V/M. Pricing for cameras designed to withstand 20V/M is way high.... .... do any of you successfully use cameras that are not as sturdy? Or ... does anyone know where we might purchase a used system?? Sandi McEnery US Technologies 770-740-0717(ph) 770-740-1508 (fax) smcen...@ustech-lab.com I can suggest two paths. I have been using an aged Sony Hi-8 Handycam. This yields an NTSC color video output and an audio output. It has autofocus. Nothing special about the camera (it was passed along to me from our corporate PR guys when the built-in tape deck died). By itself, this camera would never withstand the fields I can develop (I do the 200 V/M, 10 kHz to 18 GHz military), so shielding was needed. So, here's Path 1. I bought a 1-gallon size paint can (metal, of course). I mounted a Corcom powerline filter (with built-in male powerline connector) into the bottom of the paint can. I also mounted two BNC feed-through connectors (one each for video & audio). Connect the camera & power pack, and connect the camera outputs to the BNC connectors. I then stuffed the camera power pack and the camera into the can using stiff foam rubber. After checking the camera positioning, I cut a 1" diameter hole in the paint-can cover. Press the cover in place, and you are finished. I didn't use any screen across the open hole in the cover. I also didn't bother with any mounting hardware for the can (I use traditional military duct tape for almost everything). The paint can makes an excellent RF shield, since all the seams are soldered. The cover, when pressed in place, also yields a perfect RF seal. (Caution; fancy paint cans come with an internal plastic film to prevent corrosion. If you get this kind, you will have to use a wire wheel and buff off the plastic around the cover seal.) My gamble about no lens-hole shielding was successful, but you could always solder a patch of copper screen onto the rear surface of the cover hole. Also, the audio is transmitted through the can walls pretty well. (Audio is really great, as it lets you verify continued operation of the UUT, and allows correlation of observations with UUT operational events. And it gives you a one-way intercom.) This paint-can technique is great for shielding other support devices during a test; and the cans are available in quart and pint sizes also. Finally, the shiny paint-can makes a great statement about the frugality of your lab. But, even Sony Handy-cams must die sometime, so now Path 2. After 6 years of use, it became intermittent enough to force me to get a quick replacement. I bought a color CCD video camera, color LCD, power pack and a 65' camera cable >from Ramsey Electronics. http://www.ramseyelectronics.com/ You can download their video products sub-catalog at: http://www.ramseykits.com/catalog/pdf/2003-103.pdf I bought their CCD322 camera package for $430. At the worst, I figured I could always use the paint-can shielding technique. But the CCD322 camera looked promising, as the case was made from a tubular section of aluminum. Aside from the open lens end, there is only one circumferential seam, and that could always be covered with conductive aluminum tape. All signals and power flow through a single 65' long control cable (about a 1/4" diameter). The camera runs in color mode when there's enough ambient light, and switches to IR with its own LED illuminators as ambient light decreases. Picture quality on the associated monitor is fine, although the viewing angle restriction of the LCD (and a really cheap bracket/stand) are small drawbacks. I set the camera on a cheap plastic tripod (the camera has a cheap little mounting bracket), and ran the cable through a hole in my penetration port. I didn't do any shielding to the camera housing, and I didn't even try to ground the cable at the port. (I did route the cable as close to the floor and walls as possible, and I minimized the length of cable in the enclosure.) With this off-the-shelf configuration, I was very pleased to find that I could do 50 V/M exposure without any camera problems. In the couple of months that I have been using this system, I have done exposures up to 150 V/M at some frequencies. I noticed that the camera began to exhibit some sync problems at 150 V/M in the 600 MHz region. So, it looks like I will have to do a few things, like tape the camera body seam and ground the cable at the penetration port (and maybe examine the cable-to-camera-body ground technique), if I want to get a 200 V/M capability. The camera does a great job at high light levels, but if it decides to turn on its IR illuminators, you get a serious reflection problem. I suppose the IR LED's are only On or Off, so, if you are looking at an instrument control panel, you might have to play around with placing an auxiliary light source to prevent the IR mode. The most difficult problem I have had is observing unlighted LCD panels; this takes some time to get the camera and light source positioned to allow viewing the display without getting a reflection from the display front surface. I wish there was some remote way to suppress the IR illuminators. Finally, the camera is even waterproof. Regards, Ed Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis
