Hydrographic Survey System

With the development of economic society in our country, we present new requirements constantly for hydrology information. As the catalog and content of hydrologic observation increase, people need higher requirement for observation measure and way, research and application of hydrographic survey technology. Sensing technology, the communication technology and the rapid development of computer technology, promote the development of hydrological monitoring technology.
In hydrology monitoring system, often need to monitor the water points, most real-time monitoring data need to send to management center of backend servers.
Due to the wide distribution were scattered, and most Settings in the environment is bad, data transmission through phone line always get half the result with twice the effort. Through GPRS wireless network data transmission, become one of the means of communication to choose in hydrological department. Pollution monitoring device can be collected data and information of pollution by GPRS networks timely warning to hydrology monitoring departments, units or individuals of sewage in management can greatly improve the efficiency of hydrological department.

A.     Application and Development of Hydrology Monitoring Automation Technology

1.      The scope and content of hydrological monitoring:

Hydrological monitoring is hydrological sensor technology and collection, storage, transportation and treatment technology integration.
Monitor Range: rivers, lakes, reservoirs, channels and groundwater hydrology parameters etc.
Content: the water level, flow monitoring, velocity, rainfall (snow), evaporation, sediment and water ice, moisture content, etc.

2.      Manual monitoring technology problems:

From the traditional manual monitoring technology analysis, mainly to the following questions:
(1)    Recording way is mainly analog system, digitally recorded also difficult to facilitate the importation of computer processing.
(2)    Judging by artificial processing process, can be easily wrong.
(3)    Hydrological information collection, transmission and processing of real-time and accurate, cannot adapt the demand of modern hydrology.
Therefore, we need to use automation technology to promote the development of hydrological monitoring automation.

3.      Collection and transmission of water level

Used for automatic monitoring water-level sensor is mainly float type water, water meter, electronic draft and ultrasonic water meter, etc. These sensors can be directly to RTU, monitoring automatically parameter of water level. Monitoring of ground water is similar with surface water.
Currently, the data communications mainly use manual transcribing or PSTN line transmission between the provincial hydrologic stations and collection. Using data transmission of phone line, as every time needs to wait, slow speed, and also higher costs. At the same time, because of the wide distribution decentralizing and number, distance, individual point is remote, therefore, should apply for many telephone cable line monitoring and some difficult to reach.
GPRS has high speed, using low cost and its characteristics of transmission speed can reach 171.2 KB/s. Compared with the cable communication mode, GPRS wireless communication is very flexible, it has expanded easily, netting flexibility, low operating cost, simple maintenance and high performance, now considering using GPRS wireless transmission way to resolve the pollution sources monitoring data real-time transmission problem.

B.     Scheme Advantage

China mobile GPRS system can provide broad range wireless IP connections. The company in mobile communication platform on constructing hydrological GPRS service information collection, transmission system to collect information of hydrological wireless data transmission has can make full use of existing network, shorten the construction period, lower the construction cost advantages, and convenient installation and easy maintenance. Through the comparative analysis, we select China mobile’s GPRS system as the transmission system hydrological information collection of data communication platform.

GPRS wireless hydrological monitoring system has following features:

1.      High reliability:

Compared with the SMS message, GPRS DTU takes the TCP protocol, guarantee no packet loss phenomenon and data transmission are reliable. With multiple monitoring stations can simultaneously transmit data, not interfere with each other. GPRS networks itself has perfect frequency division multiplexing mechanism, and strong anti-jamming ability ,avoid completely the traditional digital radio frequency "crash".

2.      Real-time:

GPRS has characteristic of real-time online, data transmission delay shortly, and support more points, so the simultaneous transmission monitoring data center can be more GPRS, real-time monitor rapidly between two-way communications, well meet the system of data collection and transmission of real-time requirements. Currently GPRS actual data transfer rate in 30Kbps can completely meet system, data transfer rate(≥10Kbps) requirements.

3.      Monitor range:

GPRS networks have been realized, and nationwide coverage, unlimited expansion of unrestricted access sites, can satisfy the mountains, towns and trans-regional access requirements. Due to the large number of hydrologic information list in the range, the part is located in remote areas to collect hydrological information, and scattered location. Therefore using GPRS networks is the ideal choice.

4.      Low system construction cost:

 Due to the public network platform, without build network, only installation equipment, construction cost is low. Also save network maintenance costs.

5.      Low system operation cost:

Using GPRS public network communication, pay at the same rate all over the country, save expensive roaming charges. GPRS network can pay according to actual communication flow, (1cent-3cents/1k byte), also can pay according to monthly flat rate, to realize the low cost of communication system.

6.      Remote controlling of monitoring device:

Through GPRS two-way system can realize to reverse control equipment, such as: Time checking, status report, switch control function, and can undertake system remote online upgrade.

7.      The good transmission capacity and expansion of system:

Realize real-time connection between hydrological monitoring center and hydrological information collecting point. Due to the large number of hydrological information collecting points, system require to be met with sudden data transmission, GPRS technology can meet the requirement. Due to the system using mature TCP/IP communications structure, good expanded performance, a monitoring center can easily support thousands of site points of communication interface.

8.      GPRS transmission power consumption, suitable for outdoor environment:

Although two-way communication is far away from data center, GPRS digital equipment only need to communicate with the mobile station nearby when it’s working, the overall power consumption with a common GSM mobile phone, the average power is only about 200 milliwatt, smaller than conventional digital radio. Therefore GPRS transmission is very suitable for use in the field of solar power supply or a battery-powered occasion.

C.     Solution Introduction:

Because GPRS is based on IP address data packet communications network, thus monitoring center computer needs a fixed IP address or fixed domain, each hydrological data collecting point take GPRS module to visit the host machine through IP address and domain, and access to data communication.

(I)  System Structure

1.      Hydrological information collecting point:

Spot monitoring point collect hydrological information by hydrological testing machine, connect with GPRS DTU through interface RS232 or RS485, data from hydrological testing machine send to GPRS wireless network with the handle and protocol package of embedded processor at GPRS DTU.

2.      Hydrology center:

a)      Public network
Server take public network to connect with internet, such as ADSL dialing-up and telecommunications line broadband Internet access and so on, apply for the fix IP Add. It can realize the application of small-medium capacity data acquisition.
b)      Private network
Server take the private line of provincial mobile company, apply for the fix IP address, connect with GPRS network. Because of the high DDN available bandwidth, while environmental information to collect increase, it can meet requirements without expansion center, can achieve great capacity data acquisition and application.
First monitoring center RADIUS server start AAA authentication for data from GPRS network, then send to host computer of monitoring center, display it on the screen by system software, and start to handle the data, to enhance system data communication safety.

3.      GPRS/GSM network:

Data from hydrological testing machine is decoded by the function of interface in air of GPRS/GSM network, translate to the pattern of public network transmission, transfer through GPRS wireless data network, at last send to IP Add of monitoring center.

(II)  System Program:

Each hydrological monitoring point use the KB3000 GPRS DTU from SHENZHEN KINGBIRD NETWORK TECHNOLOGY CO, LTD, connect with monitoring center through GPRS network. GPRS DTU in each hydrological monitoring point use GPRS normal data card or APN private data card of mobile communication company, and monitoring center register each GPRS terminal, connect with hydrological points, to identify and maintenance. Collecting information center operate monitoring system software, collect hydrological information data for real-time.

Every collecting point authorized by provincial hydrological bureau can use this system:
1.      Hydrological information monitoring point must use the uniform APN card, and only for communicating with hydrological data center.
2.      Use the GPRS mobile data communication terminal from KINGBIRD NETWORK TECHNOLOGY CO, TD for terminal device.
3.      User register: Under the rule of provincial hydrological bureau.

(III)  Product Feature

System take KB3000 GPRS DTU wireless transparent data transmission terminal. The product based on GPRS network, with high performance, high reliability and anti-interference ability etc, offer standard interface RS232/485, can connect directly with PC, monolithic system, RTU terminal, PLC, GPS receiver, data concentrator and so on, has functions such as remote diagnosis, testing, monitoring, to satisfy data collecting and controlling between monitoring center and terminal point of different fields.

1.      Built-in TCP/IP protocol stack, for GPRS network optimization.

2.      Offer GPRS wireless data two-way transmission function.

3.      Offer interface RS232/RS485/RS422.