1. Background Introduction
Coal mine gas accidents are the main source of accidents with high frequency and great harm. Monitoring the state of coal mine gas is the key link to solve the coal mine gas hazards and realize coal mine safety production. Coal mine safety monitoring system is an important technical means to improve the safety level of coal mines and realize the real-time monitoring and monitoring of coal mine safety production status by the coal industry management department and coal mine safety production supervision department.
The geographical location of the coal mine is remote, the terrain is complex, the use of wired network communication network construction investment is large, the network wiring is difficult, and the maintenance cost is high. The use of microwave, digital radio, etc., poor network coverage, short distance, large user input, and difficult maintenance. The use of GPRS as a data transmission method not only meets the communication needs of the system, but also provides safer data transmission and lower user input.
When KB3030-N GPRS DTU is adopted as the data transmission carrier, the user terminal (gas sensor) can notify the relevant management personnel by SMS when the environmental parameters exceed the threshold alarm, so as to take timely measures to eliminate hidden dangers.


KB3030-N GPRS DTU features
KB3030-N GPRS DTU is a high-reliability ARM7 processor and GPRS / SMS transparent wireless data transmission terminal. The data transmission based on GPRS network has the characteristics of wide communication range, stable transmission and reliable. KB3030-N GPRS DTU is specially designed for industrial integration. It is specially designed in terms of temperature range, vibration, electromagnetic compatibility and interface diversity. , To ensure the stability of the work in harsh environments, has been widely used in areas such as unattended, remote equipment monitoring, remote data collection, remote meter reading and remote scheduling. Taking into account the needs of users in networking, support virtual data private network. It is suitable for the transmission of small and medium-sized data from the center to multiple points and scattered points.
Standard industrial grade products, EMC anti-interference design, strong ability to adapt to the environment;
Independent research and development, embedded 32-bit ARM7-CPU with real-time operating system;
 Built-in Watchdog chip, providing multiple reset mechanisms, which can be controlled by software to realize perfect industrial guarantee mechanism;
The working frequency is 850/900/1800 / 1900MHz, and the quad-band can be applied to all countries in the world (including North and South America);
Advanced and strict data communication protocol, with error correction and encryption, data transmission never loses packets;
Support multiple ways of automatic networking: can be connected with serial port-network conversion product KB2000, KB3030-N can also be networked with the same type of product as KB3030-N (convenient to use GPRS without Internet), can realize one-on-one For many groups of networks;
Plug and play function: When networking with our own KB2000 or KB3030-N, we can build a large SCADA system without any software and hardware development at this time;
IP automatic registration mechanism can realize multiple service modes and build a complete ultra-large-scale wireless application system;
Remote sleep and wake up: You can use the specified number of mobile phones to dial the DTU number to sleep and wake up the DTU, which is convenient for users to sleep when not using the DTU and greatly save traffic costs;
Remotely modify DTU parameters: support SMS to modify DTU parameters, and network to modify DTU parameters;
IO switch function: It has two switch inputs and two switch outputs. You can control the binary input or query the status of the binary input through gprs network or SMS. It can open the alarm remotely and set the input alarm mode: GPRS alarm and SMS alarm, and can set the alarm status threshold (low level alarm or high level alarm), in addition, the user can also customize the alarm information content;
Powerful communication backup function: If the backup service function is turned on, the connection between the main server and the backup server can be automatically switched, and if there is a problem with the main server, it is automatically connected to the backup server;
Powerful server software support, server software application for many years, powerful, mature and perfect;
Support fixed IP and dynamic domain name resolution, support dedicated APN;
Support the function of synchronizing up to 4 servers. If the GPRS server synchronization function is enabled, KB3030-N can register and communicate with 4 servers at the same time;
Support up to 20 SMS control numbers;
Industrial temperature range: Working temperature: -40 ℃ -80 ℃, communication is not affected at -40 ℃.
3. System configuration

(Figure) Schematic diagram of coal mine safety monitoring system
The coal mine safety monitoring system requires that all kinds of data collected underground can be transmitted to the ground monitoring center in a safe, timely and effective manner, transmitted to the network center through the GPRS wireless network, and then transmitted to the local coal monitoring center and superior safety supervision department through the dedicated line or the Internet .
The coal mine safety monitoring system is mainly composed of three major parts: data collection terminal, wireless data transmission network platform, and coal monitoring and management center system.
1. Data collection terminal: uninterruptible power supply, KB3030-N GPRS DTU, sensors (gas, temperature and humidity and other sensors), etc.
2. Wireless data transmission network platform: GSM network, Internet (VPN), server.
3. Coal monitoring and management center system: Internet (VPN), user control software.