Design And Implementation Of Receiving Device For Wireless Multichannel Nuclear Magnetic Resonance Detector

Magnetic Resonance Sounding(MRS)is a non-invasive geophysical method for detecting groundwater,which has the advantages of directly and quantitatively describing the location,thickness and water content distribution of underground aquifers,and has unique interpretation results,and can realize one-dimensional,twodimensional and three-dimensional imaging.With the development of multichannel instruments,the MRS system has included a transmitting part and a multi-receiving part working at the same time,and simultaneously carry out multi-point measurement,thus improving the working efficiency of the site and the ability to distinguish aquifers of different terrains.However,the current multichannel nuclear magnetic resonance instruments all use wired synchronization,which has certain restrictions on the number of acquisition channels.The upper computer at the measurement site only performs control and simple data storage and display,so its calculation and analysis ability are insufficient.Therefore,the detection area of the instrument is limited,and it is difficult to implement measurement methods such as remote reference noise cancellation.In view of the existing problems of current nuclear magnetic resonance water detection instrument,this paper designs and implements a multichannel nuclear magnetic resonance detector receiving device based on wireless communication technology.Finally,through simulation test and field experiment,it is proved that the receiving device designed in this paper improves the applicability of nuclear magnetic resonance water detection instrument in complex environment,and improves the practicability,convenience and expandability of the whole system.The main research contents are as follows:(1)The hardware part of the receiving device of the wireless multichannel nuclear magnetic resonance detector is designed,including the main control board of the wireless multichannel nuclear magnetic resonance acquisition station to realize the functions of communication,power conversion and synchronous triggering,etc.The acquisition module collects data with 24-bit precision and 52.734 k Hz sampling rate,the signal multi-stage amplification design of the amplifier and the design of synchronization during system operation.Based on this,the decoupling of the transmitting/receiving hardware part of the MRS system is realized,and the number of acquisition channels of the instrument is increased.(2)Design the software and communication part of the wireless multichannel MRS detector,including the upper computer software design for data distributed computing and the design of data communication in the system by using wireless bridge communication technology.At the same time,increase the number of instrument acquisition channels to more than 24 channels,the measurement efficiency of the detection is improved,and the measurement methods such as the application of remote reference noise cancellation are realized.(3)The function,performance and overall simulation test of the receiving device of the wireless multichannel MRS detector are carried out,and the system was tested in the field environment.Through the simulation test of wireless data communication,it is verified that the application of wireless bridge communication technology in MRS instruments is correct and reliable;By testing the amplifier in the electromagnetic shielding room,the gain range is 10-78000 times,the noise floor is 3.6 n V/(?)Hz,the bandwidth of broadband filtering is 2.2 k Hz,and the minimum signal detection capability is 3.6 n V.Through the test of analog signal,the effectiveness of the system is verified;In addition,further experiments in field application prove the detection performance,reliability and stability of the receiving device of the wireless multichannel MRS detector developed in this paper in practical environment.In summary,the research work in this paper expands the measurement range of MRS water detector,which can realize the synchronization of the system without hardware connection.By adopting wireless communication and realizing the distributed computing ability of the upper computer of the system,the efficiency and accuracy of obtaining detailed 2D and 3D information of groundwater in the detection area are improved,and the foundation for the realization of various measurement methods is provided.