An analysis of the signal line technology of the future development trend of (1)

Security is as to the likely harm acts, events, advance prevention, timely detection and ex-post evidence.

Signal a line through the emergence of new technologies, without increasing the number of cable, using a new frequency and time transfer technique enables monitoring system can realize video monitoring, bi-directional audio intercom, bidirectional alarm linkage, accident prevention features. Application of new technology can be implemented on a cable transmission of multi-channel video and two-way audio and video, bidirectional alarm linkage, RS485 signal, phone signal, fire signal etc. The application of this technology can bring security industry in the most important monitoring and alerts in two parts, enabling passive monitoring, alarm into active prevention, audio broadcasting and alarm linkage control, realization of interactive.

Common first-pass technology of the "many"

We all know, the cable TV available through one cable to TV stations more channels of TV programmes on a TV show clearly that this mature technology applied to security in the common line technology.

As early as the beginning of the century, began to someone with a cable modem to the monitoring system, then there is dedicated to monitoring the signal line pass products.

Through one cable can not only be the front-end multiple camera audio and video signals to the control center, you can also transfer from the monitoring center reverse RS485 yuntai control signal.

This is based on the frequency (frequency assignment) technology is the camera's output of 0-8MHz audio and video signal modulated to 49.75MHz-860MHz above band, 1 per 8MHz bandwidth modulation signal, audio video modulation signal is mixed into one cable transmission, in Terminal demodulation out audio and video signals.

In the Terminal to the RS485 signal modulation, reverse transfer to 38MHz.

Common first-line pass features a transmission signal tree structure, so that the control signal to the nearest access point, is to transfer audio and video signals, reverse transmission 485 control signal, high-frequency modulated so that it has strong anti-jamming ability, can save cable and work costs, ease of upgrading the system.

Compare broadband signal "one line" monitoring and traditional analog monitoring of some of the advantages

1) wiring cumbersome, construction complex: a coaxial cables can only transmit one channel video signal wiring, construction, construction of a long life cycle;

2) transport limited, extremely inconvenient: standard transmission distance of 300 meters, cannot achieve long-distance transmission, plus video amplifier make amplification of noise and, image quality cannot be guaranteed;

3) is not easy to expand, difficult to maintain: Add monitoring points back cloth video cable, construction is extremely inconvenient.

Because the fabric cable too much hassle to maintain;

4) control transfer, another fabric cable: cannot implement bidirectional transmission, desired single cloth RS485 control cable, so that the original complex systems more cumbersome;

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