LARGE-SCALE DISTRIBUTED 2D/3D FDIP SYSTEM BASED ON ZIGBEE NETWORK AND GPS

Abstract We realized a 2D/3D multi-frequency FDIP instrument system based on ZigBee wireless network and GPS to improve the data quality and efficiency of 2D/3D IP survey for engineering, environment and mineral exploration problems. The instrument is composed of a multi-function transmitter and more than 50 receivers. The transmitter is synchronized with GPS and can transmit more than 30 user defined waveforms and pseudo-random waveforms with frequencies range from 1/256 Hz to 128 Hz for field and laboratory usage. All receivers are identical with the ability to make the measurement of current injected into the earth and the potential difference between two electrodes. Each receiver is composed of 4 signal channels, DSP subsystem, GPS subsystem, and embedded computer subsystem. The DSP subsystem receives digital signal from four 24-bit A/D converters and carries out a sequence of filtering and calculation to reduce noise and interference inside the digital signal to improve signal to noise ratio (SNR). The GPS subsystem generates clock signal and synchronization signal for A/D conversion. This ensures all receivers doing data acquisition simultaneously. Therefore, the injected current and potential differences are measured at same time. This is the key for additional SNR improvement in IP survey. The embedded computer subsystem is the brain of the receiver. It is composed of wired network, WI-FI, ZigBee, ARM SOC, SDRAM, NOR flash, and NAND flash. A PC with a ZigBee adapter is used to control the data acquisition and monitors the data quality through ZigBee network. A lot of tests showed that more than 50 receivers can be controlled in the field with short latency. Therefore 196 voltage measurements and 1 current measurement can be made at a single acquisition. This improves the data quality and efficiency of 2D/3D IP survey significantly.