3G wireless monitoring and WIFI wireless monitoring analysis

Now that the wireless monitoring industry is becoming more mature, the market is very hot. Currently, wireless monitoring on the market is roughly divided into two major categories: one is 3G wireless monitoring; the other is wireless monitoring with WIFI as the carrier. Now many users are not very clear when choosing wireless monitoring which way is more suitable for the project in hand. Here is the fundamental difference between the two for everyone to choose.

It is divided into 2G and 3G modes; one is the previous 2G mode test, and the other is the latest version of the 3G mode.

(1) 2G wireless monitoring

Its transmission methods mainly include CDMA and GSM modes. The two modes have lower hardware cost, large coverage and slow transmission speed. The theoretical value transmission rate is up to 153.6Kbps, and in practice, it 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 the wireless monitoring project, few manufacturers choose. Another biggest drawback is that the traffic charges charged by operators are too high, and every month, every year, there will be a large cost. Generally, it will only be considered if it is very remote and WIFI wireless devices cannot do it.

(2) 3G wireless monitoring

Adopting mobile (TD-SCDMA), telecom (CDMA2000 EVDO), and Unicom (WCDMA) operators' 3G technology access methods, since 2009, through the promotion of various operators, many monitoring manufacturers have developed related to this aspect. The product. The outstanding advantage of 3G is the high-speed download capability, and the ideal value can reach the transmission rate of 3Kbps~20Mbps. However, because it is still in the promotion stage, it still needs further research on the transmission rate. 3G currently has the defects of limited wireless bandwidth capacity, limited access users, and extended time. In the case of multi-user sharing, it is difficult to guarantee the rate and delay requirement of wireless video surveillance. The main disadvantage is that the traffic fee charged by the operator is too high. General customers cannot accept.

WIFI wireless monitoring is divided into two modes; one is analog wireless monitoring; the other is digital wireless monitoring.

(1) Analog wireless monitoring

The video signal is directly modulated on a 2.4G or 1G wireless channel, and transmitted through an antenna. The monitoring center receives the wireless signal through the antenna, and then demodulates the original video signal through the wireless receiver. This monitoring mode 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-range (within 1KM) single-channel transmission, not suitable for scale deployment. In addition, because there is no modulation and calibration process, the anti-interference is poor, and the frequency is small. Therefore, when the wireless signal environment is complicated, it will cause great interference, causing image confusion and loss. Therefore, in the case where there are multiple images to be transmitted, transmission in this way is not recommended.

(2) Digital wireless monitoring

The video signal is first encoded and compressed, modulated by digital wireless channel (2.3G/2.4G/5.8G, etc.), and then transmitted by the antenna. On the opposite side of the receiving end, the signal is received by the antenna, followed by wireless despreading and video decompression, and finally reduced to analog video signal transmission. This method is also widely used in the domestic market. The digital microwave has large scalability, and the communication capacity can use 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 advantages that analog wireless is incomparable. For example, large area (5-30 square kilometers), monitoring points (5-500 points) need to be relayed, and the situation is complicated. The center cooperates with the front-end CPE equipment of the base station to transmit the cost performance very high. The digital wireless has large capacity, strong anti-interference ability and good confidentiality. The same transmission power transmission distance is farther, the terrain or obstacles are less affected, the interface is rich, and the expansion capability is strong.

Of course, different wireless transmission technologies have their own suitable locations. For example, in factories, oil fields, border defenses, forests, etc., wireless monitoring using WiFi is more, with the improvement of 3G performance, the reduction of traffic costs, the maturity of the network environment, and the general demand for wide-ranging wireless monitoring. Further use of 3G.