What is a security system and how does it work?
Video security systems or CCTV are a powerful and versatile security option for the home business. There is now a wide range of components or full system available to choose from to suit most applications. From the minimal system of a single camera at the house front door, to a large system of many cameras for throughout a home property or business building.
CCTV means “closed circuit television” and is the general term used for any private or security agreement for video cameras and monitors. While some new video cameras may transmit to a base station, the term CCTV is still used, although it originally referred to cameras connected by wiring alone.
The range of components and system found here allow simple and flexible setups for monitoring or security. Monitors showing pictures from well-located cameras provided immediate information on an area of concern, areas such as;
Around the house:
- The front or rear door of the dwelling, for security.
- The backyard, rumpus room or swimming pool, where the children are playing.
- The garage or street frontage, incase of intruders.
For the business:
- Shop display areas, incase of shoplifters.
- Cash tills, entrances or exits and public transition areas.
- Dangerous, inaccessible or prohibited factory areas, fro staff safety and security.
- Property perimeters, for safety and security. Read more…
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What is a TV signal?
To understand how TV reception works, it helps to know how TV signal is generated. At the TV station an analogue camera or telecine machines scans scenes into 576 horizontal lines, 25 times per second, producing a sequential electrical representation of the scenes .sound and timing pulse are added to produce a “baseband” analogue video signal.
For digital broadcast, specialized computers analyze film or scene sequences and calculate digital descriptions of the changing images. This combined with data representing sound and other information to produce a stream of “baseband” digital data.
How are TV signals broadcasted?
The TV station sends its baseband signals to one or more transmitter’s sites where they modulate high-power, radiofrequency signals, called “carriers” which carry the TV signal. The transmitter is collocated with the broadcast antenna which is mounted high atop a tower or building so it can cover a wide area. The broadcast antenna takes the electrical signal from the transmitter and radiates it as electromagnetic waves.
The modulated frequency signals occupy 7MHz (megahertz) wide channels. For analogue broadcast, each channel carries a single program but digital technology fits several programs into the same channel space.
In Australia, three radio-frequency bands are used for TV broadcasting:
- VHF (Very High Frequency) Low – frequencies from 45 to 70 MHz (channels 0-5) – analogue only.
- VHF (Very High Frequency) High – frequency from 85 to 230MHz (channels 5A to12).
- UHF (Ultra High Frequency) – frequencies from 526 to 820MHz (channels 28 -69).
What is an antenna and how does it work? Read more…
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What is a DVD recorder and how does it work?
A DVD recorder records TV or video source material to DVD discs. Like the VCR, the DVD recorder has an in-built tuner to receive the TV signal from an antenna or cable or satellite feed, and an analogue video input to record from sources such as video camera or VCR. Whereas the VCR records onto videotapes, the DVD recorder writes to writable DVD discs.
Some better DVD recorders include hard drive to improve recording performance or provide some of the extra features of hard disk DVRs (digital video recorders) or PVRs (personal video recorders).
As the TV or video signal has to be compressed by the recorder for recording in an MPEG format, a common option is to allow the available recording time to be increased by reducing picture quality. This allows the user flexibility to chooses between using more DVD space for high quality recordings, or saving space by choosing a lower quality record setting.
What are the advantages of DVRs over VCRs?
No tapes – with a VCR, the device records onto the large removable VCT tapes. In a DVD recorder, the recording is either to an internal hard drive, or to the common DVD discs.
Playback control – unlike a VC, you don’t have to wait for the tape to rewind before watching it, as DVD access tine is fast. Some hard drive DVD records allow the program to be paused or interrupted or watched form the start while still recording, but this only applies to DVRs, PVRs or DVD recorders with advanced features. Read more…
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