Understanding Hard Disk Recorders

The late 1980's saw the introduction of video multiplexers offering users the facility to record pictures on to a single video tape, eliminating the need for VCRs dedicated to recording a single camera output.

The use of time-lapse VCRs as a storage medium for those images is well known, as are their inevitable drawbacks - introduction of noise, wear and tear and the simple requirement that the tape needs to be rewound to access information. In a practical situation the reviewing of tapes to secure the important face shot" or "scene of crime" can involve long and tedious work.

The late 1990's have seen the emergence of Hard Disk Recorders (HDRs) that are essentially multiplexers with a computer hard disk memory to store images. HDRs are excellent at reproducing high quality images with little noise or picture degradation and are extremely useful in calling up an alarmed picture.

A problem that HDRs faced, however, was that computer memory was still relatively expensive compared with a storage medium such as videotape.

The struggle for many HDR manufacturers was to produce a machine that provided the features and performance required with sufficient memory to make it a practical machine at a realistic price. Now, with computer memory being available in hundreds of Gb at a relatively low cost, Hard Disc Recorders have finally come of age. The advantages over VCR's are many. HDRs are able to record in VHS mode (the same quality as a standard VCR), SVHS mode (the standard used by the highest quality VCRs and giving over 60% better resolution than standard VHS) and SVHS+ (not available with VCRs).

Further to the above a VCR and it's tapes begin to wear and deteriorate from the moment they begins recording while Hard Disk recording should remain at the same high standard throughout it's working life. This means that even in VCR mode the quality will, in most cases, be superior to what would be achieved on a standard Video Recorder.

In addition to the above HDRs offer a number of additional features not available with Multiplexers.

1. The ability to view and control the system from computers around the world.
2. Interconnectivity to Computer networks.
3. Built in Motion Detection for setting alarm events and immediate retrieval.
4. The ability to go direct to a time or incident without the need to search through hours of videotape.

Next-Generation Digital Video and Audio Recording

Also available now is the next-generation digital video and audio recording solution, this is designed for casinos and other high-security, real-time recording applications.

Highlights

• Up to 30 frames per second NTSC/25 fps PAL, per camera - high frame rates enable users to extract the most information from their digital images
• Up to 96 camera inputs per unit - saves space, requires fewer components, and increases reliability
• Improved picture quality - high recording resolution provides superior definition and clarity allowing for optimum event monitoring and analysis

Written by http://www.cctv-information.co.uk/