Whether high-definition monitoring can be quickly applied and popularized requires not only the front-end high-definition equipment manufacturers to provide a series of mature high-definition products, but also a flexible and diverse product selection for users to build high-definition monitoring systems. The overall monitoring effect of the HD solution and the cost-effectiveness of popularized applications are also crucial factors.
The premise of HD monitoring application is network
The first thing to consider after collecting high-definition pictures is the problem of video signal transmission. High-definition video places higher requirements on transmission.
A high-definition video signal requires three coaxial cables to be transmitted simultaneously. Digital transmission generally adopts DVI, HDMI or HD-SDI transmission. The transmission distance of DVI or HDMI is only a few meters, which is not suitable for monitoring transmission. Although HD-SDI can transmit about 100 meters, the requirements for coaxial cables are very high The price of the cable is also very expensive. Regardless of analog or digital transmission, the transmission cost of uncompressed high-definition video signals is significantly higher than previous analog standard-definition video signals. When video compression encoding is adopted and transmission is performed through an IP network, the difference in transmission cost between high-definition video and standard-definition video is small.
Therefore, it can be seen that high-definition surveillance must first be based on video compression processing and transmitted through an IP network. Only in this way can the transmission cost of high-definition video be effectively controlled, so that high-definition surveillance is truly practical.
Small computer system interface (SCSI) is an independent processor standard for system level interfaces between computers and intelligent devices (hard disks, floppy drives, optical drives, printers, scanners, etc.). SCSI is an intelligent universal interface standard.
The last SCSI device in the SCSI chain uses a terminator, and the intermediate device does not need a terminator. Once the terminator is used by the intermediate device, the SCSI card cannot find the future SCSI device. If the last device does not use a terminator, SCSI will not work properly. Terminator is composed of resistors, located at the end of the SCSI bus, to reduce the mutual influence of the signal, maintain the constant voltage on the SCSI chain.
Most of the SCSI devices have built-in terminators and use a jumper to control on / off. The SCSI device is highly intelligent and can automatically control the terminator on / off. For example, if a hard disk is connected to a CD-ROM, the CD-ROM can work normally regardless of whether the terminator of the hard disk is on or off. However, when two hard disks are connected, the situation becomes more complicated. Before two Seagate hard disks are connected, one hard disk terminator must be off. Before a Seagate hard disk is connected to a quantum hard disk, a hard disk terminator can work normally regardless of whether it is on or off.
SCSI-90°DIP Section
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