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Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059
Would a "lasing detector" make a viable commercial product methinks? ie if it detects polarized light an alarm is sounded and cameras near the lased one activate countermeasures such as switchable c-pol filters.
Registered Member #3215
Joined: Sun Sept 19 2010, 08:42PM
Location:
Posts: 780
I think a saturation detector would be more efficient... once blind, it screams
detecting >90% of pixels higher than brightness level X is easier than telling it is coherent light, as you would need a cavity like a fabry-perot or other etalon for a specific wavelength (or a scanning fabry perot with a wide enough bandwidth), which is unrealistic
Registered Member #902
Joined: Sun Jul 15 2007, 08:17PM
Location: North Texas
Posts: 1040
considerations to think of:
- viewing location (as was already mentioned keep it in your property)
- storage (regular desktop grade HDDs will wear out very fast due to the constant movement. They make HDDs oriented around video feeds. they aren't as fast but they will last longer for the purpose. Also RAID can be beneficial as the files can get large and you obviously want it to be reliable).
- light spectrum. A lot of systems use IR for night vision, but as mentioned this can be blinded with a laser pointer. If you are worried about hooligans in the night, then you have to consider if they are the kind to be smart enough about this. Most decent security cameras will have an auto-adjusting iris that will account for sudden or large sources of light. However, they are not perfect. While a normal visible light camera can be blinded with a bright light, people in the area can see it.
- Type of connectivity. If you use IP cameras, try to put them on a different LAN (physically or with a VLAN) than your actual network. It is common to tap into outdoor IP cameras with this method to abuse someone's network (we do this at work in my security firm all the time). For WiFi it should be a different network and key, and a different routing configuration so it cannot see your regular network. Depending on requirements (such as remote viewing etc), you may have to use something such as a DMZ.
- monitoring. Cameras are useful in a few ways. If they are monitored by a guard at a business, they can be both preventative and for evidence. In a home there tends to not be a full time monitor, so they have to be reviewed afterwards. In that case, you have to consider the length of time you are willing to store footage, and where you store it. If you store it on a NAS in the same house it monitors, then a thief who sees the cameras and goes in anyways may just grab the NAS or smash it. Even if he doesn't know its camera footage, computer and tech gear always looks shiny to any thieves.
I hope this info helps. There are a LOT of options and without knowing more about your case couldn't make any recommendations.
Registered Member #3215
Joined: Sun Sept 19 2010, 08:42PM
Location:
Posts: 780
movement detection through video processing is mandatory if you don't want the bigger raid to be full in a day or two...
also, if you are looking for affordable cameras, almost none will have an iris but they will usually have an AGC built in the silicon which will serve the same purpose, but doesnt protect the sensor array
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