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Shenzhen Changhong Microelectronics Co.,Ltd

Surveillance Camera Basics Knowledge Part B

What is IP video surveillance?


A: IP is an acronym for Internet Protocol (Internet Protocol), one of the most commonly used protocols for communicating over a computer network. The IP surveillance solution is to transmit video information in digital form over a wired or wireless IP network. Video monitoring and recording is guaranteed as long as the network is reachable, and this monitoring can be combined with many other types of systems.


What is a video amplifier?


Answer: When the video transmission distance is relatively long, it is better to use a video cable with a thicker line diameter. At the same time, the video amplifier can be added to enhance the signal strength in the line to achieve long-distance transmission. The video amplifier can enhance the brightness, chrominance, and sync of the video, but the inter-line interference signals are also amplified. In addition, too many video amplifiers cannot be connected in series in the loop, otherwise saturation will occur, resulting in image distortion.


What is the RS-232 serial interface standard?


A: RS-232 is the most widely used serial interface in the PC and communications industries. RS-232 is defined as a single-ended standard that increases communication distance in low-rate serial communications. RS-232 adopts an unbalanced transmission method, so-called single-ended communication.


What is the RS-422 interface standard?


A: RS-422, RS-485, the data signal uses differential transmission, also known as balanced transmission. The full name of the RS-422 standard is "the electrical characteristics of the balanced voltage digital interface circuit", which defines the characteristics of the interface circuit. RS-422 four-wire interface. There is actually a signal ground, a total of 5 lines. The maximum transmission distance is 4000 feet (about 1219 meters) and the maximum transmission rate is 10Mb/s. The length of the balanced twisted pair is inversely proportional to the transmission rate, and it is possible to reach the maximum transmission distance below the 100 kb/s rate. The highest rate transmission is only possible at very short distances. The maximum transmission rate that can be obtained on a typical 100-meter twisted pair is only 1 Mb/s. RS-422 requires a terminating resistor that requires a resistance equal to approximately the characteristic impedance of the transmission cable. There is no need to terminate the resistor when transmitting at the moment distance, that is, the resistor is not required to be terminated below 300 meters. The terminating resistor is connected to the farthest end of the transmission cable.


What is the RS-485 interface standard?


A: RS-485 is developed from the basis of RS-422, so many electrical regulations of RS-485 are similar to RS-422. If balanced transmission is used, it is necessary to connect the termination resistors on the transmission line. RS-485 can be used in two-wire and four-wire modes, and two-wire system can realize true multi-point two-way communication. RS-485 differs from RS-422 in that its common mode output voltage is different, RS-485 is between -7V and +12V, and RS-422 is between -7V and +7V, RS-485 receiver The minimum input impedance is 12k ohms, while RS-422 is 4k ohms; RS-485 meets all RS-422 specifications, so RS-485 drivers can be used in RS-422 networks.


What are the similarities and differences between RS-422 and RS-485?


A: RS-422, RS-485, the data signal uses differential transmission, also known as balanced transmission. RS-422 four-wire interface. There is actually a signal ground, a total of 5 lines.


RS-485 adopts two-wire mode, and two-wire system can realize true multi-point two-way communication. RS-485 is different from RS-422 in that its common mode output voltage is different.


What is a video switcher?


A: The video switcher is a key device on the main console in the control center. It is the device that selects the video image signal. Simply put, several video signals are input, and by controlling them, one of the video signals is selected. In a television monitoring system composed of a plurality of cameras, it is generally unnecessary to display the image signals of the respective cameras one by one with the same number of cameras as the number of cameras.


What is a multi-screen split controller?


A: Using image compression and digitization, several images are compressed on the screen of a monitor in the same proportion. Some also have a built-in sequence switch function, which can display the full-screen image input by each camera in turn on the monitor in sequence and interval (as in the case of switching the host to switch the screen), and can use the recorder as described above. The order and time interval are recorded. The interval is generally adjustable. It has sequential switching, picture-in-picture, multi-picture output display playback image, connected camera alarm display, touch-type pause screen, alarm record playback, time, date, title display and other functions.


What is a video splitter? VDA (VideoDistruibutingAmplifier)


A: The distributor is the most commonly used component in the distribution network in a cable transmission system, and is used to distribute the components of the signal. Its function is to equally divide one input signal into several outputs, usually two allocation, three allocation, four allocation, six allocation and so on.


What is video switching control?


A: The central processing module of the matrix system controls the video switching of all camera inputs and monitor outputs. Switching can be controlled by the operation of the keyboard, or by performing a system switching queue, or an automatic response function of an alarm.


What are the system switching methods for matrix systems?


Answer: Matrix system switching can be divided into five kinds of system switching methods: free switching, program switching, synchronous switching, group switching and alarm switching.


What is the free switching of the matrix system?


A: A free-switching queue is a cyclic display of a set of camera inputs programmed onto a monitor. Each camera screen can stay at different times, and each monitor has an independent switching queue.


What is the program switching of the matrix system?


A: Multiple queues are tuned to any monitor by the operator or by a timed call at any time. Each group of switching queues can be composed of multiple cameras and their preset points, dwell time, and auxiliary switching actions. In a group of switching, multiple auxiliary actions of the same camera picture or one camera may occur multiple times.

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