DVRs providing Security and Surveillance in your home or office

Just a few years ago perhaps the simplest of CCTV systems was just a camera linked to a display or screen and then the next major step was the Video Recorder. This major step was how things stayed for quite a while with a range of enhancements and technical developments but the VCR has remained the key element of CCTV systems for 20 to 30 years. The CCTV systems for home or office security included switching systems and multiplexers enabling multiple monitoring or camera points to be included onto the same tape. The great hurdle however was the tape which was always the same length and always had to be changed. Hence multiple recorders could be batched together, at a cost, almost like a jukebox thereby providing further recording time. How often have we heard of systems where the tape was full or just hadn’t been inserted into the recorder!

Now we have a major step forward with the Digital Video Recorder or DVR. The DVR employs many of the basic features of the VCR but by using Digital technology is able to provide a complete new meaning to CCTV, home or business security and surveillance systems. The DVR avoids many of the human errors made by VCR users. The software developments have become more and more sophisticated but the relatively low cost of hard disk space has transformed how data can be stored. It’s not long ago that the 1 terra-byte of storage would require several drives incorporated into some sort of RAID array. We are now seeing 1 terra-byte low cost drives in the stores. The cost between a RAID array 5 years ago and a single 1 terra-byte drive is probably in the order of 100 to 1 and that alters entirely how security, surveillance and CCTV are able to embrace the new technologies.

The DVR can be a standalone device or increasingly a computer system incorporating a multi-channel data capture device typically enabling the connection of 4, 8 or 16 cameras via a wired or wireless technology. Bosch and Sanyo are two reputable manufacturers marketing stand alone devices but inevitably the cost of a PC plus the cost of a data capture card from Geovision or Avermedia for example is little more than the stand alone DVR and you get a PC to use. Equally you could just add the cards to an existing PC if you have a modern machine with adequate disk storage.

DVR software is obviously important and would normally be shipped with the appropriate card or system. There are software vendors supplying third party software which they believe provide added functionality or increased ease of use. Clearly how you go about choosing your system depends very much on your own requirements so try and list what you think you need. Is your system for home security and surveillance or business security and surveillance? A small business system maybe similar to a home system in specification. It’s also possible now to have mobile systems which link a small camera and satnav or gps system to provide an exact location of where the recording is being made. This could again be useful for a business to locate its drivers.

If a system is intended for home use you will need to establish how many points you wish to monitor and do your cameras need to be fixed or moveable with tilt and zoom features. Would you wish to have remote access from any web based location? How many hours of information would you like to record? Would you like to include movement sensors or infra-red cameras? Do you have a budget?

There are so many questions to consider and browsing various vendors’ websites will give you more of an insight to what products are available and the costs of components. Some sites provide screen shots, video and download demonstrations.

An hour’s worth of one channel of uncompressed video at 25 frames per second would take up 21,600 megabytes (21.6 GB)

Uncompressed video of one hour will take hard disk space

Frame size 320*240 Pixel at 25 frames per second would take up

25*3600* 230400 Byte = 20736 Mega bytes

= 20.736 GB (24 bit color)

25*3600* 307200 Byte = 27648 Mega bytes

= 27.648 GB (32 bit color)

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