Digital Radio in the Police / Fire / Traffic Wireless Data C
First, the pros and cons of the public network
Through the GPS system for location tracking of moving targets on land need to have appropriate wireless data communication network, public network, GSM, CDPD, GPRS and other systems with extensive coverage, multi-cell system, base stations, high data rate, 9600bps or more, effective and reliable transmission of information etc., is to provide GPS vehicle anti-theft alarm system, the best class of business communication platform.
Public network for the public service, channel sharing, on the fee, send text messages now 0.1 yuan / time, the user is large, likely to cause congestion and loss of information, can not guarantee real-time messaging, there is the institutional sector statistics on send and receive text information, the average time is 11 seconds, a long time of more than 30 minutes (see 2000 “Mobile” magazine).
In order to save costs and is not limited to the people, high-capacity real-time applications like business to build their own GPS system to be dedicated wireless data network platform.
Second, the feasibility of building special network
Dedicated wireless data network base station equipment investment is not large, no duty, and maintenance personnel. Effective coverage radius of a single base station in the small mountain city and non-stop up to 30 km region, large cities, because of built-up generation of multi-path fading radio transmission, effective coverage radius of up to 15 km. Network through a multi-base station synchronization, to achieve large area coverage, greatly expanded the coverage of Wireless Network.
Real-time applications like GPS system, updated every few seconds to locate information, are generally restricted to a particular region, within the range of tens of kilometers, invest a few million to establish a dedicated wireless data networks, operating costs are low, than using the public network platform effective, cost-effective.
Third, what kind of radio station — the size of private network users
User capacity is dedicated wireless data networks of key indicators.Wireless data network subscribers by radio data rate, conversion time and send and receive information transmitted decision.To meet the requirements of large-capacity, dedicated wireless data networks, radio stations must provide high data rates, such as 19200bps or more, and be able to quickly send and receive conversion time 10ms period.
The current dedicated wireless data network devices are basically using conventional FM radio plus the realization of the MODEM.Radio work in 230MHz, 800MHz band data transmission business and 350MHz, 800MHz trunking services band.In 25KHz, data rate is basically 1200bps, 2400bps, a number of other uses GMSK MODEM chip to the output of the low frequency signal applied directly to the VCO input to achieve 9600bps wireless data transmission, but the way of the RF specifications, difficult to meet the Ministry of Information Industryrequirements, and the 10-6 bit error sensitivity is very low, very close communication, which can not actually use.In addition, the conventional FM radio transceiver in 50-100ms conversion time around, can not send and receive high-speed conversion.
Shenzhen Sinosun Company uses forward error correction coding, software radio, digital modulation coherent demodulation, Viterbi soft decision and the integration of design, surface mount technology to provide high-performance, high stability, high reliability and DSP radio.Radio 232 provides a standard interface directly with the computer, GPS receiver, control panel connection.25KHz channel spacing of the air data rate of 19200bps ,10-6 BER sensitivity of-111dBm, transceiver switching time in less than 7ms, radio and other indicators in line with the requirements of the Ministry of Information Industry.
Assume that each user terminal needs to transmit 50 bytes of information, the use of Sinosun radio just distribution:
50 × 10 ÷ 19200 +7 = 33ms time slots to each station.
Likewise, the use of FM radio stations plus MODEM, usually 2400bps way you need to allocate:
50 × 10 ÷ 2400 +50 = 258ms time slots.Two kinds of user capacity difference of about 8 times.If the GPS system requires updated information every 10 seconds, using the FM radio plus MODEM way can not accommodate 40 users, while the use of the Shenzhen Huaxia Sheng station can accommodate 300 users.
In addition, we in the same environment, such as the center of Shanghai, currently the most dense urban high-rise experiments done.Provided with a domestic FM 9600bpsMODEM way data radio communication only less than 2 km (BER less than 10-6), while the Shenzhen Sinosun radio can cover about 15 km radius.
Shenzhen Sinosun is China’s earliest radio stations engaged in the development of wireless data transmission manufacturers of products are widely used in petroleum, electricity, banking, water treatment and other fields of telemetry, remote, remote control, similar 65% share of China market.Shenzhen Sinosun companies operating in all frequency bands simplex car units, duplex base stations, base stations and hot standby 2.4GHz frequency-hopping spread spectrum radio, radio with remote diagnostics and network management functions can be easily depending on the terrain, regionalthe formation of a variety of wireless data network.
Single base station dedicated wireless data communication network
More base stations dedicated wireless data communication network
Fourth, the application case
1, APEC Meeting vehicle scheduling system
Specific advantages of wireless data communications platform in October 2001 APEC meeting in Shanghai has been most fully manifested, high-speed data radio with Huaxia Sheng GPS system shows the composition of its power.Huaxia Sheng digital radio transmission rate is high, send and receive change rapidly, reliable, multiple-site testing with outstanding performance, by the praise and approval of experts, held in Shanghai this year, several important international conferences have played a role.
During the APEC meeting, many heads of state gathered in Shanghai.To ensure the smooth progress of the meeting, heads of state of vehicle scheduling requires accurate real-time positioning.From Pudong airport to the hotel where he stayed heads to the convention center, 30 kilometers along the highway; urban areas, tall buildings, bad wireless conditions.President Jiang Zemin at the conference center to meet the heads of the parties, requires every head of state vehicles in 1 minute intervals in order to reach a second can not early nor late.Dispatching of vehicles to meet the requirements of each head of state limousine is equipped with a GPS positioning system.Huaxia Sheng stable and reliable high-speed data radio, once per second to provide location information, vehicle command and control orderly, all the car in place on time.Shanghai APEC meeting successfully concluded, the Shanghai Public Security Bureau of the high-speed data transmission by the GPS positioning system, the State Council of praise and recognition.After the meeting, the leaders visited the particular system.
2, the Shanghai public security command system
To enhance the city public security management, the Shanghai police patrol grid system tried to patrol the city is divided into 217 areas, the formation of grid-based layout, each patrol district self-contained grid with responsibility for police, 24-hour patrol in the street leaving, the security control surface mesh refinement to each patrol district, responsibilities to the police who each grid.
Mechanism for the implementation of the patrol grid, have changed in the way Guard and static branch police station, the distribution of more than 3,500 police patrol in the city’s 217 grid area, and will lay street unified command, coordinate with each other, greatly improving the site captured the probability of crime. Street patrol in the back, there is a strong chain of command behind it. If you experience a major emergency, Council will immediately start the chain of command, commander based on the facts raised by the plan immediately operational support system solutions.
After the patrol grid system implementation, needs to have a Weapon of that to come and capable of fighting and winning the police force. Thus, since 2000, police in Shanghai in batches of more than 5,000 patrolmen, security police, police station focused on the training base, was closed two and a half of intensive training. They closed during the day for training, the evening turns on duty, as a standing fighting force. According to statistics, the implementation of grid-based patrol system, the Shanghai street snatch captured more than 30 percent rate, while the street-Robbery cases in the first half than the same period last year dropped by 30%. Urban law and order situation has improved significantly.
