Research Of Soil Nutrient Rapid Detection System Based On GPRS Technology

In recent years, crop cultivation techniques in constantly improve, at the same time, detection, automatic control and communication technology is also continuously penetrate the facilities of agriculture.In order to realize rapid detection of soil nutrient information and remote wireless transmission, requires the use of high precision of the sensor and advanced data transmission module. This paper analyzes the domestic and foreign professionals, on the basis of research on the subject, to join the authors some thinking on the subject, make full use of the present all kinds of advanced technology, research and development the soil nutrient measuring system based on GPRS technology.This thesis mainly done the following work:(1)Paper first through the demand analysis, determine the research content for soil ammonium nitrogen, nitrate nitrogen, available phosphorus and available potassium of speed measurement system development.(2)In order to implement on a system to test the various soil nutrient, determine the working principle of the sensor for the photoelectric colorimetry.After extensive access to information and according to the measured soil nutrient color features, chose the 625nm,420 nm,420 nm LED light-emitting diodes and hamamatsu G1155, Huashang photoelectric HSPD450-116EMB silicon photocell as the sensor.Using ICL7650MJD design of photoelectric conversion circuit, signal amplification.PCF8591 chips are made with the A/D conversion module for analog-to-digital conversion electrical signal after amplification, finally With STC89C52 single-chip control eight common-cathode digital tube transform modulus data display.In order to timely send the data to the data processing platform, using the single chip microcomputer to control the global hawk SIM900A V3.7 module, rather than to a serial port communication, the detected information by sending text messages to make information in a timely manner to the mobile terminal, the received information for data processing, can quickly get measured soil nutrient information.Using LM2596S module design based on 24V dc voltage battery 5 V,3.6 V,2.8 V dc regulated power supply for LED light-emitting diodes (leds) and other power supply module.(3)After completion of system design, to test their ability to work.Experimental results show that the measurement results to establish the system of soil nutrient standard curve correlation coefficient R2 was 0.9973,0.9866,0.9947 and 0.9988, respectively, can use the above standard curve to calculate soil nutrient measuring values.Based on 30 samples speed measurement value and conventional established speed measured value to the conventional value transformation model and 20 samples for inspection.Results showed that the soil ammonium nitrogen, nitrate nitrogen, available phosphorus and available potassium transformation model error average were 0.37,0.41,1.02,0.37, error standard deviation was 0.77,0.49, 1.14,0.49, respectively.Errors are generated in the allowed range, showed that soil nutrients to make use of this system speed measurement is feasible.