How Do I Choose the Best GSM Wireless Phone?

GSM-R (Global System for Mobile Communications-Railway) is an international wireless communication standard for railway communications and applications. The subsystem of the European Railway Traffic Management System uses GSM-R to complete the communication between the train and the dispatch center. The system is based on GSM and EIRENE-MORANE , and it will not lose any communication when the speed is up to 500 km / h (310 mph).

As early as the 1920s, railways in some countries began conducting wireless communication tests between locomotives and the ground. In the 1940s, many countries successively installed tube radio telephones on trains, using medium and short wave bands. In the 1950s, short-band point-to-point wireless communication was generally used. In the 1960s, with the development and application of transistors and integrated circuits, railway mobile communications used a large number of very high frequency (VHF) and ultra high frequency (UHF) frequency bands. In terms of equipment, the size is reduced, the weight is reduced, the power consumption is reduced, the reliability is increased, and it can adapt to various climatic conditions. After the 1970s, the combination of microprocessors and transceivers made the equipment signaling more complete and flexible, with functions such as automatic channel search, automatic user access, automatic power control, and automatic device failure monitoring. Railways in some countries have begun using wireless passenger train telephones that connect to the wired telephone network. In the 1980s, besides railway railway dispatching command, railway mobile communications were also widely used in various railway business departments.

In the 1950s, China's railway station watchkeepers and marshalling yard line watchers began to use train wireless dispatch phones and station radio phones, using electronic tube equipment operating at 2MHz and 40MHz. In the early 1970s, all switched to 150MHz and 450MHz transistor devices. In the early 1980s, the use of small-scale 150MHz and 450MHz radio stations in the marshalling yard was promoted. Radiotelephones for maintenance operators along the railway have also been popularized. The wireless alarm device for road maintenance and construction has also been rapidly developed and applied, and the wireless dispatch telephone test of the train in the mountain tunnel section has been conducted.

The main performances of the wireless communication equipment in the station are: the transmitter clutter suppression ratio is usually required to be above 60dB, the combined wave suppression ratio is required to be above 70dB, the receiver blocking attenuation should be above 80dB, and the intermodulation immunity should be above 60dB. .

The radio alarm device is provided to prevent the train from entering the line maintenance, construction section, and to prevent accidents at crossings, bridges, and tunnels, and to warn the driver, between the driver and the construction section, between the driver and the crossing, and between the driver and the lineman. Between alarm devices. This device must be absolutely reliable and have a special use mark. Its working distance is within a few kilometers, and the alarm time is about 10 minutes. It uses a unified national dedicated frequency and achieves automatic detection as much as possible.

The wireless communication used by other railway workers mainly includes the radio telephones used in the area, maintenance personnel, and other telephones widely used in railway work, such as radio telephones for survey and construction, maintenance operations, rescue trains, and railway public security. These radiotelephones use civilian frequency bands and do not occupy railway-specific frequencies, so as not to interfere with transportation scheduling operations. Intercom wireless telephones generally use universal

The GSM-R communication technology originated in Europe. At present, it has entered commercial use in most countries such as Germany, Switzerland, the Netherlands, Italy, and Sweden. Because GSM-R has the functional advantages of adapting to the characteristics of railway transportation, and more in line with the needs of the development of integrated communication and signal technology, the Ministry of Railways officially decided at the end of 2000 to adopt GSM-R as the development direction of China's railway dedicated communications.

GSM-R adds special dispatching communication functions for railway transportation on the GSM public mobile communication system platform. The GSM-R communication system includes: switches, base stations, locomotive integrated communication equipment, mobile phones and other equipment. Take the Qinghai-Tibet Railway as an example: The Qinghai-Tibet Railway is the highest-altitude railway line in the world. The Qinghai-Tibet Railway starts from Golmud, Qinghai Province in the north, passes through Nachitai, Wudaoliang, Luohe, and Yanshiping. After crossing the Tanggula Mountains into the Tibet Autonomous Region, Via Amdo, Nagqu, Dangxiong to Lhasa, the capital of the Tibet Autonomous Region, the total length is about 1142km. Most of the routes are in the no-man's land on the plateau. In order to meet the needs of railway transportation communication, signal and dispatch command, GSM-R mobile communication system is adopted.

GSM-R is based on the GSM technology standard. Because GSM-R focuses on railway applications, in the existing network, GSM-R adds three more functions than the public network, namely voice group call service VGCS, voice broadcast service VBS and enhanced The multi-priority and forced teardown of eMLPP is also collectively referred to as the Advanced Voice Call Project ASCI service. Because of this difference, the products of manufacturers supporting public network GSM cannot be used directly in the GSM-R network. Unless the ASCI service is specifically developed, the manufacturers that currently support GSM-R are ZTE, Nokia Siemens Networks (Nuoxi), Huawei, COMLAB Kapch (formerly Nortel, acquired by Kapch), etc.

The dispatching communication system business includes train dispatching communication, freight dispatching communication, traction substation dispatching communication, other dispatching and dedicated communication, station communication, emergency communication, construction maintenance communication and crossing communication.

2.Transmission of train number and transmission of train stop information

The transmission of train number and train stop information is of great significance to railway transportation management and driving safety. It can implement data transmission through the data acquisition and transmission application system based on GSM-R circuit switching technology, and it can also be implemented by GPRS.

3. Scheduling command transmission function

The railway dispatching order is a written order given to the driver by the dispatcher in the dispatching office, and it is an important guarantee for train safety. Using the GSM-R system transmission channel to transmit scheduling commands will undoubtedly speed up the transmission process of scheduling commands and improve work efficiency.

4. Information transmission function of train tail device

The tail wind pressure data feedback transmission channel is incorporated into the GSM-R communication system, which can conveniently solve the problem of tail wind pressure data transmission.

5.Transmission function of shunting locomotive signal and monitoring information system

Provide shunting locomotive signal and monitoring information transmission channels, realize data transmission between ground equipment and multiple on-board equipment, and can store relevant information for entering and exiting shunting mode.

6. Train control data transmission function

The GSM-R communication system is used to realize two-way wireless data transmission between the car and the ground, and to provide a two-way secure data transmission channel between the car and the ground.

7. Inter-regional mobile business communications

The internal communication of the departments of water and electricity, engineering, signal, communication, power supply, bridge guarding, etc. in the section can use the GSM-R operating handheld table, and the operator can communicate with the station attendant, each department dispatcher or automatic telephone when needed. User contact. In an emergency, the operator can also call the driver to establish communication with the driver.

8. Voice and data services for emergency command communications

The emergency communication system is to establish a voice, image, and data communication system between the emergency site and the rescue center, and within the site when an emergency that affects railway transportation occurs, such as a natural disaster or emergency. . ^[1]