Design Of Small Archeological Device Based On High Density Electrical Method

Archaeology is an important subject in the study of human civilization.The archaeological process can be divided into the early investigation stage and the later refined excavation stage.In the early investigation stage,the main detection targets are grave pits,foundations and other large targets,and more traditional detection methods can be used in this stage.Currently,high-density electrical instruments can image resistivity at ranges of several hundred meters,the depth of detection can reach tens or even hundreds of meters,but the resolution is about a few meters,which is an effective means of early archaeological investigation.However,in the later stage of fine excavation,the main detection targets are smaller objects such as ceramic pieces,bamboo slips and seals,with the size of centimeter.It is difficult for existing electrical methods to detect their specific distribution.In order to detect the distribution of underground resistivity anomalies,judge the distribution of cultural relics,so as to protect cultural relics,this paper designed a small archeological electrical detection device with centimeter electrode spacing based on the high-density electrical method.The hardware of the small archeological electrical detection device designed in this paper adopts modular design,which mainly includes the control,transmitting,acquisition,array electrode and communication module.The main control module mainly consists of MSP430 microprocessor and CPLD,which realizes the functions of parameter setting,transmission timing sequence generation,trigger acquisition and array electrode control.The transmitting module mainly includes AC/DC power,constant current circuit and H bridge circuit.The transmitting frequency is programmable and adjustable,the maximum transmitting voltage is300 V and the maximum transmitting current is 0.1A.The acquisition module mainly includes attenuation circuit and synchronous acquisition circuit.It can realize synchronous data acquisition of 8 channels with 24 bit and maximum 105 KSPS.The structure size of the array electrode module is 1m×1m,and it is composed of 100 electrode circuit boards of 0.1m×0.1m.Several array electrode modules have the capability of cascade expansion.The array electrodes are spaced 5cm horizontally and vertically,and 7cm diagonally.Each electrode has four optically isolated solid state relays,enabling rapid programmable function switching.The software consists of three parts: lower computer,control software and data processing software.The main implementation of communication,parameter setting,data acquisition,data processing and other functions.The small archeological electrical detection device designed in this paper was used to test and verify the sand experimental model built in the laboratory.The main detection parameters are as follows.The size of the array electrode is 1m×1m,the number of electrodes is 20×20,a total of 400.Emission frequency is 100 Hz,emission voltage is 60 V,emission current is 0.1A.The acquisition module is used to receive the voltage at both ends of the electrode.The experiments were carried out to detect centimeter-level small targets with different depths and different resistivity,and the measured data were processed and the 2.5-dimensional imaging.The self-developed electrical method equipment can detect the range of 1m×1m×0.2m.