3G wireless monitoring Strictly speaking, it is divided into two kinds of 2G and 3G mode; One is the earlier 2G mode test, the other is the latest version of the 3G mode test. 1,2 G wireless monitoring transmission including CDMA, GSM modes. This two modes lower hardware cost, coverage, slow transmission speed, the theoretical value of the transfer rate of up to 153.6Kbps, in actual use, basically reached only 60 ~ 80Kbps. Because the video image to the bottom requires 512Kbps smooth transmission, this speed is far less than the video requirements. Therefore, wireless monitoring projects, few manufacturers to choose. Another one of the biggest drawback is that the flow of charge carriers fee is too high, every month, every year, will have a large amount of money. Generally only in very remote, WIFI wireless devices can not do in the case, and have some funds will be considered. 2,3 G wireless monitoring is the use of mobile (TD-SCDMA), Telecom (CDMA2000 EVDO), China Unicom (WCDMA) carrier's 3G technology access, from 2009 onwards, by the operators to promote, many monitoring For this regard manufacturers research and development related products and services. The prominent advantage of the 3G high-speed download capability, the desired value can be achieved 3Kbps ~ 20Mbps transmission rate, but because it is still in the promotion stage, the transmission rate to be further research in this area. 3G wireless bandwidth of existing capacity is limited, the limited access users, the extended defects, in the case where multiple users share, it is difficult to ensure a rate of wireless video surveillance and delay requirements, the main drawback is the flow of charge carriers is too costly General customers can not accept it. WIFI wireless monitoring Strictly speaking, WIFI wireless monitor is divided into two kinds of ways; one is analog wireless surveillance; Another is digital wireless monitoring. 1, analog wireless monitoring is modulated video signal directly or 1G 2.4G wireless channel through the antenna out, the monitoring center receives a radio signal through the antenna, and through the wireless receiver demodulates the original video signal, this monitoring means no compression loss, almost no delay, thus ensuring that the video quality, but is only suitable for short distance point (1KM less) single-channel transmission, not suitable for scale deployments. Also because there is no modulation of the calibration process, poor immunity, low frequency, so the wireless signal environment complex case itself will generate a lot of interference resistance, resulting in an image confusion, loss and so on. Therefore, the image to be transmitted in a number of road situations, we do not recommend using this mode transmission. 2, the digital radio signal is to monitor the first video encoding, the digital radio channel modulation (2.3G/2.4G/5.8G, etc.), re-use antenna. Receiving end, in contrast, the signal received by the antenna, then despreading and wireless video decompression, and finally restore the analog video signal transmission out, this approach is currently used in many domestic markets. Digital Microwave scalability large communication capacity of at least dozens of channels available and relatively easy to construct, high communication efficiency, the use of flexible. Digital radio has not comparable analog wireless advantages, such as large area (5-30 km), monitoring points more (5-500 points) need to add repeaters many cases, the situation is complex and the source of interference for a long time using LP5800-WBS WIFI base station as the center together with the front-end CPE devices transmit a very high cost. Digital wireless capacity, anti-interference ability, good security, the same transmit power over longer distances, less affected by the terrain or obstacles, rich interfaces, scalability and strong. Of course, different wireless transmission technology has its own appropriate places. Such as in factories, oil fields, border, forests, etc., using the WIFI wireless monitoring more, along with all aspects of 3G performance improvements, traffic costs decline, the maturity of the network environment, as well as a wide range of wireless monitoring of widespread demand will induce further use of 3G. |
