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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Wireless Security Systems
Anybody have experience with wireless security 4+ camera systems ?
Are these systems 'bluetooth' and fight for throughput? Good ones for outdoor use? Any URL with a block diagram? I know, but google returns sales and eBay and Amazon, not information. |
#2
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Wireless Security Systems
On Tue, 11 Oct 2011 11:15:58 -0700 (PDT), Robert Macy
wrote: Anybody have experience with wireless security 4+ camera systems ? Yep. I bought a loser on eBay and now know what NOT to buy. Are these systems 'bluetooth' and fight for throughput? Huh? No Bluegoof in sight. What you're thinking of is 802.11b/g also known as Wi-Fi. The problem is that 4 active Wi-Fi cameras will occupy 100% of the available bandwidth in the 2.4GHz band. They will also trash your 2.4GHz cordless phone, your wireless internet to your laptop and iPhone. The picture will go nuts when you run the microwave oven. Wireless cameras are a dumb idea. Use coax cable, or get a pair of baluns and use CAT5 for the cameras. I switched to CAT5 and am living happily ever after. Good ones for outdoor use? Outdoor is always a problem because of temperature and potential water damage. You can do ok by enclosing the camera in a heated enclosure (to reduce lens fogging), but a real outdoor camera is always prefered. Any URL with a block diagram? This weeks favorite vendor: http://www.securitycamerasdirect.com There's not much to it. Just 4-16 cameras, some coax or CAT5, a DVR box where it all comes together, an ethernet connection to your network, a local VGA monitor, a mouse, etc. I bought the bare DVR without a hard disk drive and added my own at considerable savings. A huge headache is the absolutely worthless software for remote monitoring and searching the archives. The allegedly "free" software continues to expire after 30 days, even though the vendor claims that it's been fixed. The user friendly interface was apparently designed for non-humans. Hint: Spend you money on decent cameras. Pay attention to the resolution spec. For outdoor, you'll need an (expensive) auto iris lens. There are numerous web sites to help you calculate what size lens to get. Connect a decent digital camera with a video output to the DVR and compare the images with a cheap NTSC camera. If you can actually recognize people on the cheap camera, it's probably ok. However, it will rarely be as good as the digital camera. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#3
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Wireless Security Systems
Per Robert Macy:
Anybody have experience with wireless security 4+ camera systems ? Are these systems 'bluetooth' and fight for throughput? Good ones for outdoor use? Any URL with a block diagram? I know, but google returns sales and eBay and Amazon, not information. I'm far from an expert - in fact I have been trying to climb the same learning curve for over a year now. Having said that.... Look at band width/resolution. My experience so far has been that wireless cams (WiFi is the only method I've looked at) just don't return good enough motion or detail to be useful. Accordingly, I have been focusing on IP cams that work over hard-wired Ethernet. For allowing one to view cameras from afar, besides hooking into the camera's native web page, the only app I have found so far that seems to do the trick is WebCamXP. -- PeteCresswell |
#4
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Wireless Security Systems
On Tue, 11 Oct 2011 12:52:21 -0700, Jeff Liebermann
wrote: On Tue, 11 Oct 2011 11:15:58 -0700 (PDT), Robert Macy wrote: Are these systems 'bluetooth' and fight for throughput? Huh? No Bluegoof in sight. What you're thinking of is 802.11b/g also known as Wi-Fi. The problem is that 4 active Wi-Fi cameras will occupy 100% of the available bandwidth in the 2.4GHz band. They will also trash your 2.4GHz cordless phone, your wireless internet to your laptop and iPhone. The picture will go nuts when you run the microwave oven. Wireless cameras are a dumb idea. Use coax cable, or get a pair of baluns and use CAT5 for the cameras. I switched to CAT5 and am living happily ever after. That wasn't very clear. Wireless security camera systems do not use Wi-Fi (802.11). They use conventional NTSC analog transmissions on approximately 1/4th of the 2.4GHz band. It's not VSB as the signal is about 12MHz wide. There's no acknowledgements from the receiver, and there's no listening on the channel to see if it's occupied. Just one way broadcasting and interference to existing Wi-Fi systems. Sorry for the muddle. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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