Digital video surveillance history
During last 30 years video surveillance have evolved from analogue CCTV equipment, to completely digital systems. Devices like network camera and network video recorder came to replace old CCTV equipment.
Same migration from analog to digital systems happened in all other areas of technology.
Now digital sound and video recorders, photo cameras, mobile phones have replaced their analog ancestors. In few years we will see complete disappear of analog radio and TV broadcasting.
It is easy to distinguish few steps on the way of video surveillance digitalization.
First video surveillance systems were based on analog video cameras connected to a VCR. That time a security guard was sitting in front of black and white monitor. Usually the monitor screen was divided to 4 or 16 areas to show video from few cameras. Professionals called such systems Close Circuit Television – CCTV.
After a while VCR was replaced with digital video recorder (DVR). DVR solved such problems as degrading video tape quality with time and eliminated needs to change video tapes.
- No need to play with VCR tapes
- Consistent quality of recorded video
Next step was migration from DVR to network DVR. Network connectivity gave remote monitoring feature and possibility to connect remote PC.
- Remote monitoring and control from another PC
The next step was replacement of network DVR with video server and PC. Video server is used to grab video signal from cameras and send it to PC equipped with video recording/management software.
The great advantage of PC video processing is an easy installation. You don’t need to put lot of coax cables around your building and a way more advanced motion detection.
- PC based motion detection
- Remote Recording is possible
But the bad thing in these steps is a double video conversion – At first at camera video converted to analog signal to put it into the coax cable. And the second conversion from analog signal to digital in DVR.
The last step of digitalization is switch to fully digital surveillance systems based on network cameras, where video server is built in video cameras. In this case network camera makes digitization, compression and some times even motion detection.
- Easy to install, because of IP(Internet Protocol) network video transmission
- High resolution surveillance (1280*1024 and more) is possible
- Wireless surveillance based on wireless cameras is possible
- Full scalability
- Easy to send control signals to PTZ devices
- Two way audio transmission on the same wire
Gartner forecasts, by 2008 the network cameras market will overcome market of traditional analog CCTV cameras.
