Wireless data transmission system according to different business needs, can be divided into the wireless computer local area network and a wireless remote telemetry system. Wireless computer network operations including data, voice, image information of the data stream, multipoint structure, support TCP / IP protocol, provides an Ethernet interface. Wireless data telemetry system supports asynchronous remote data-to-multipoint structure, polling work, using the RS232 interface.
The earliest use of short-wave wireless data transmission, plus FM radio MODEM other way, for weather, customs, civil aviation, and other special departments of CRT data terminal for data transmission between the small amount of data, data rate in 2400BPS below.
With the proliferation of computers and the expansion of automation, wireless data transmission for installation flexibility and are more widely used. Remote telemetry application delivery platform, including special network of conventional analog radio frequency plus MODEM, conventional-band digital stations, analog or digital trunking radio paging and public networks, GSM SMS and GPRS, in addition to infrared, 2.4GHz Bluetooth, 2.4 GHz WI-FI, 406MHz Distress Beacon Warning, etc.. Different platforms because of its system architecture, the terminal function is different from the remote telemetry to analyze wireless data transmission applications, with different characteristics.
|
Analog radio plus MODEM |
Digital Radio |
Digital trunking
|
GSM short message
|
GPRS |
|
|
System equipment |
Self-built special network
|
Self-built special network |
Build a special network |
Shared public network |
Shared public network |
|
System investment
|
Single base station about ten thousand yuan
|
Single base station about ten thousand yuan |
About one million yuan a single base station
|
Billion or more regional system
|
Billion or more regional system
|
|
System covers |
20-50kilometer |
20-50kilometer |
10-30kilometer |
Regional
|
Regional
|
|
Frequency band |
230/350/400 MHz |
230/350/400 MHz |
800 MHz |
800/900 MHz |
800/900 MHz |
|
Terminal cost (approximately) |
2500（25W） |
4500（25W） |
5000（15W） |
1000(0.6W） |
1500（0.6W） |
|
Maximum transfer rate |
2400BPS |
19200BPS |
9600BPS |
9600BPS |
171KBPS |
|
Real-time |
Hundreds of milliseconds
|
Tens of milliseconds
|
Seconds
|
Average seconds |
About 1 second
|
On transmission reliability, an air transport should be said that there is no way to absolutely reliable, interference may cause errors, need to be absolutely reliable transport protocol (such as feedback retransmission, etc.), error due to high reduced efficiency caused by poor real-time.
Can be concluded from the table:
1, public GSM, GPRS platform approach for large regional transmission and real-time remote telemetry less demanding applications, such as vehicle alarms with GPS.
2 dedicated digital or analog data radio method is applicable to small areas and real-time requirements of remote telemetry applications such as industrial automation.
3, dedicated digital trunking for small areas and less demanding real-time remote telemetry applications, such as information inquiry.
Can be concluded from the table:
1, public GSM, GPRS platform approach for large regional transmission and real-time remote telemetry less demanding applications, such as vehicle alarms with GPS.
2 dedicated digital or analog data radio method is applicable to small areas and real-time requirements of remote telemetry applications such as industrial automation.
3, dedicated digital trunking for small areas and less demanding real-time remote telemetry applications, such as information inquiry.
|
Analog radio plus MODEM |
Digital Radio |
Digital trunking
|
GSM short message
|
GPRS |
|
|
System equipment |
Self-built special network
|
Self-built special network |
Build a special network |
Shared public network |
Shared public network |
|
System investment
|
Single base station about ten thousand yuan
|
Single base station about ten thousand yuan |
About one million yuan a single base station
|
Billion or more regional system
|
Billion or more regional system
|
|
System covers |
20-50kilometer |
20-50kilometer |
10-30kilometer |
Regional
|
Regional
|
|
Frequency band |
230/350/400 MHz |
230/350/400 MHz |
800 MHz |
800/900 MHz |
800/900 MHz |
|
Terminal cost (approximately) |
2500（25W） |
4500（25W） |
5000（15W） |
1000(0.6W） |
1500（0.6W） |
|
Maximum transfer rate |
2400BPS |
19200BPS |
9600BPS |
9600BPS |
171KBPS |
|
Real-time |
Hundreds of milliseconds
|
Tens of milliseconds
|
Seconds
|
Average seconds |
About 1 second
|
