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Guide to Closed Circuit TV (CCTV)

So would you like to play "Spot the CCTV Camera?". Eagle eyed visitors may recognise the profusion of street furniture, surrounding a single heritage dome camera keeping watch over part  of Londons' prestigious Oxford Street shopping area.

Time Lapse, VCR's, DVR's, NVR's ...
it's time to go on the record...

The options for Archiving Recordings

As Doktor Jon has already mentioned, most DVR users are generally unaware of the potential benefits provided by storing recordings for longer than the limited ‘overwrite’ period, dictated by the recorders resolution, frame rate settings and hard disc drive capacity.

In practice, if a well set up record system has been equipped with a significant HDD array, perhaps 160 or 320GB (or larger), it would probably be cost prohibitive to attempt to use any system of automatic disc back up, that wasn’t going to break the bank.

The main problem is most large data storage systems (apart from RAID which can be both expensive and questionable in terms of overall reliability for some security applications) cannot run fast enough to keep up with the Digital video recorder, and the smaller (faster) removable media are generally limited in storage capacity, so you’d have to use dozens if not hundreds just to store the contents of one large HDD drive; still some machines do allow connection to a PC or external HDD for parallel recording.

So unfortunately, apart from the old analogue approach of recording a tape then storing it, which would of course still apply to a Digital tape based system, for Hard disc recorders, the options can be somewhat limiting.

If you’ve recorded an incident on a well ‘ard hard disc, now what are the options for transferring that crucial data onto a portable media? Well, perhaps the obvious and most common solution is to ‘burn’ a disc, which for many users might have been a ‘CD’ (700MB), although for more modern systems, a rewriteable DVD (4.7 or 9.4 GB) presents a more appropriate and flexible solution.Incidentally apart from DVD-RAM, there are concerns over the longterm storage of data on other DVD formats, which have recently been found to degrade much quicker than expected.

That said, a limited number of manufacturers are already offering Blu Ray discs as a back up medium, with the current standard 50Gb disc due to be upgraded shortly with a 100Gb varient.

There are of course, no end to the options for using various formats of recordable media, including mini DV (Digital Video) Tape, CompactFlash, Microdrive, DAT tape; and then some DVR units will also offer the option of connection to an Ethernet 10 Base -T Local Area Network (LAN), using a PCMCIA or SCSI card, which of course will allow distribution or copying of images in any number of different permutations.

To find out what are the recommended options for any individual DVR, you’ll really need to consult the manufacturer or their distributor. As to which option best suits your needs, that will very much depend on the way you use a Digital recorder, what if any standards or requirements are developed longerterm within the Criminal justice System (CJS), and also what you expect from it in terms of quality.

The issue of evidential integrity >>

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