There are roughly two types of wireless monitoring currently on the market: one is 3G wireless monitoring; the other is wireless monitoring based on WIFI . The following is the fundamental difference between the two for your choice.
1 3G wireless monitoring
It is divided into 2G and 3G modes; one is the previous 2G model test, and the other is the latest version of the 3G model.
(1) 2G wireless monitoring
Its transmission mode mainly includes two modes of CDMA and GSM. The hardware cost of these two modes is low, the coverage is large, the transmission speed is slow, the theoretical transmission rate is up to 153.6Kbps, and in practical use it basically only reaches 60 ~ 80Kbps. Because the bottom of the video image requires 512Kbps for smooth transmission, this speed is far from the video requirements. Therefore, in wireless monitoring projects, few manufacturers choose. Another biggest disadvantage is that the traffic fees charged by operators are too high, and a large amount of fees will be incurred every month and every year. Generally, it will be considered only when it is very remote and WIFI wireless equipment is not available, and there is a certain amount of funds.
(2) 3G wireless monitoring
The mobile (TD-SCDMA), telecommunications (CDMA2000 EVDO), and China Unicom (WCDMA) operators ’3G technology access methods have been used. The product. The outstanding advantage of 3G is the high-speed download capability. The ideal value can reach a transmission rate of 3Kbps ~ 20Mbps, but because it is still in the promotion stage, it still needs further verification in this regard. 3G currently has defects such as limited wireless bandwidth capacity, limited access users, and time extension. In the case of multi-user sharing, it is difficult to guarantee the rate and delay requirements of wireless video surveillance. The main disadvantage is that the traffic fees charged by operators are too high. General customers cannot accept it.
2 WIFI wireless monitoring
WIFI wireless monitoring is divided into two ways; one is analog wireless monitoring; the other is digital wireless monitoring.
(1) Analog wireless monitoring
That is, the video signal is directly modulated on the 2.4G or 1G wireless channel, transmitted through the antenna, the monitoring center receives the wireless signal through the antenna, and then demodulates the original video signal through the wireless receiver. This monitoring method has no compression loss. There is almost no delay, so video quality can be guaranteed, but it is only suitable for point-to-point short-distance (within 1KM) single-channel transmission, not suitable for large-scale deployment. In addition, because there is no modulation and calibration process, the anti-interference is poor, and the frequency is low, so in the case of a complex wireless signal environment, it will cause great interference itself, causing image confusion and loss. Therefore, it is not recommended to transmit in this way when there are multiple images to be transmitted.
(2) Digital wireless monitoring
That is, the video signal is first encoded and compressed, modulated by a digital wireless channel (2.3G / 2.4G / 5.8G, etc.), and then transmitted using an antenna. The receiving end is the opposite. The antenna receives the signal, then wirelessly despreads and decompresses the video, and finally restores it to an analog video signal for transmission. This method is also currently used in the domestic market. Digital microwave has great scalability, and the communication capacity can be at least dozens of channels, and the construction is relatively easy, the communication efficiency is high, and the application is flexible. Digital wireless has the incomparable advantages of analog wireless, such as large area (5-30 square kilometers), many monitoring points (5-500 points), there are many situations that need to add relays, the situation is complicated and the interference source is many. The center and the base station front-end CPE equipment transmission mode is very cost-effective. Large digital wireless capacity, strong anti-interference ability, good confidentiality, the same transmission power transmission distance is farther, less affected by terrain or obstacles, rich interfaces, and strong expansion capabilities.
Of course, different wireless transmission technologies have their own suitable places. You need to choose different methods according to your own situation and needs.
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