The formation of business units with their own digital radio station dedicated remote telemetry wireless data transmission network, such as set up than fiber optic cable, cable, leased line and wireless DDN such as GPRS, the device has a system of high performance, flexible and easy to install open, stable and reliable operation, managementeasy maintenance, low operating costs benefits of opening.
1、What circumstances to use wireless?Why build a private network?Choose what radio?
Compared with the wireless, wired data transmission reliability and better, larger advantages.But whatever their aircraft leased telecom line or lines, not wireless so open and flexible installation quick and relatively long-distance transmission, equipment and operating costs than wireless high.Therefore, in the distance and set up the case of inconvenience can only use wireless data transmission.
Wireless transmission of data many ways, can be easily divided into private and public networks.Build their own private network is set up the master radio, digital radio equipment costs about 3,000 to 5,000 yuan, the antenna mounted on the ground about 30 meters or more can be transmitted 20 to 30 kilometers or more (frame relay).In addition, the construction of non-private network but also to the local Committee for a dedicated frequency (usually 230MHz band), if you do not want to apply, can only use 2.4GHz spread spectrum radio band.With the public network to transfer data, is the use of Mobile and China Unicom's GSM, CDMA public network platform, to buy GPRS module, secondary development, go to the local Mobile and Unicom for the appropriate procedures to use.Apply each year to pay special network frequency, a frequency of about 1,000 yuan per year, renting public network platform, including IP addresses to pay rental charges (static IP) and data traffic charges.Therefore, the system requires a wide range of coverage or the amount of data transmission terminal is not the case, a good way to use the public network.In the large volume of data, real-time requirements of high, covering the range of 50 kilometers with built-in way of cost-effective private network and not by others.
Simply select the private network construction is to use data radio.Of the radio use from the earliest key codes, telegraph to the analog station plus wireless MODEM, to the current digital radio and DSP, software radio, signal transmission from the code, low-speed data (300 ~ 1200bps) to high-speed data (N * 64K ~N * E1), can include remote telemetry data transmission, digital audio, motion graphics and other services.Currently used data transmission stations, mainly analog radio plus MODEM, digital radio, Internet radio and other images.
Digital data radio using DSP chip, channel coding, forward error correction.It uses digital modulation and demodulation of CPFSK, coherent demodulation, Viterbi decoding, soft decision equalization technology, software, processing gain of 7dB.Received field strength with instructions such as bit error statistics, alarm indication, the local network remote maintenance and remote diagnostic capabilities, transfer rate up to 19.2Kbps, send and receive conversion is less than 7mS, with a variety of PLC, RTU, instrumentation and other direct connections, support for MODBUS, Profibus and other protocols, you can achieve one to many (polling mode) and many to one (report type) transmission.Digital radio is currently the market price between 2500 ~ 5500.
2、How to build a private network to complete the procedure?
All wireless devices have to use are first detected by the radio network license management committee, to get into private network or public network, including radio, GSM mobile phones. With the radio network to be built specifically to the local (municipal) No committee submit a written application, indicating the use of unit name, purpose, scope, etc., without the Commission's Office issued a receipt of the application that the application form, fill in Name of units required , address, purpose, intended for use in equipment and its corresponding indicators, and an operational frequency assignment, several transmission stations used in 223.025 ~ 235.625MHz band.
Users can purchase equipment according to the frequency. Equipment installation opening after use, no committee will notify the local frequency occupation fee to pay, concurrent use of the radio card. If in the course and found that radio interference, no committee can notify the monitoring station, the unit has the most advanced testing equipment to correct the interference.
3、How to build a private network maintenance?
Special network equipment, including main and sub-station radio station, occupied a special frequency. Special network maintenance, including the main station, sub-station radio equipment management, Antenna seal seepage water, the sea and radiation protection, promptly contact frequency interference-free committee, so the private network maintenance is very simple.
Attachment: Commission on National Radio on frequency allocation, fees, interference investigation and other information please check the following website: http://www.srrc.org.cn
