Choosing A DVR
For
businesses that do not want to constantly
change tapes, DVRs are definitely the way to go. While
security VCRs usually
offer a time-lapse mode that lets them for
long periods of time, the
resulting images are not a good record of events - they record only one
snapshot every eight seconds. To get higher quality, you need to change tapes every day or more often.
DVRs, on the other hand, can record for weeks or even months.
DVRs are more considerably more expensive than VCRs, which is their only major drawback. However, the
DVR prices have fallen considerably over the last year and will continue to do so. Already, low-end DVRs and high-end VCRs are in similar price ranges, and most manufacturers have stopped introducing new VCR models. Despite the increased cost, we recommend video security system buyers purchase a DVR whenever possible.
Choosing a DVRAs part of your CCTV shopping preparations, decide how much quality you need out of your recorder. There is no magic number or spec here: you need to decide how "good" the recorded picture needs to be, either for your own use later or possibly to use in court. Once you decide this, you will be able to look at samples on the DVRs you are evaluating and see if they meet your standard. Vendors may be eager to throw compression settings, pixel counts, and other statistics at you - but those numbers are irrelevant if the picture itself does not offer the detail you need for legal or investigatory purposes.
The size of the hard drive will dictate how much you can record. On the low end, an 80-gigabyte (GB) hard drive will store about five to eight days of full-motion video from one camera. Most of the time you will not be recording full motion, so this is much more than it might seem. For most businesses, spending a little extra to get 120 or 240 GB is a worthwhile investment. Units expand up to 1.2 terabytes (1,200 GB), which can store many cameras' worth of
data for long periods of time.
Replaceable hard drives are a cheap way to boost storage capacity. With some DVRs, you can buy additional hard drives for as little as $150 and swap them in and out as you need. This gives you the advantage of being able to store your data separately from the main
security system.
You will also need to consider how many cameras you want to connect to the DVR. Keep your future expansion needs in mind - buying a higher-grade model to get more inputs and more storage space can save you considerable money in the future. The DVR will also function as a
multiplexer, putting up to 16 cameras on one display and allowing operators to call up any one image for closer inspection.
Also, if you ever have to use your
security images - in court or in other ways - you will need to be able to export the video. This is an important consideration: some systems let you create industry-standard .avi files, which can be played on any
PC, and burn them to CD. Others only allow you to export proprietary formats that can only played on the same brand player. Most DVRs do offer the option to connect a standard VCR - this allows you to simply tape the
digital recording onto a standard VHS cassette.
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