Research On Magnetic Data Pretreatment Of Proton Magnetometer

Obtaining accurate target magnetic anomaly by magnetometer is the key to themagnetic exploration. As an important branch of the second generation ofmagnetometer, the proton precession magnetometer, with its high precision, easy tocarry, and other advantages, has become the most widely used ones in magneticexploration. In order to obtain reliable magnetic anomaly, magnetometer needs touse the correct way of working, and also we need to do data correction to eliminatethe interference. Before the interpretation research, the data needs to be transformedand filtered to protrude the anomaly. These are the pre-treatment work to be done.In order to enrich the function of the magnetometer developed by our team, andto meet the requirement of the PC software, key issues of data pretreatment isstudied, including instrument checks, data correction, coordinate transformation,magnetic anomaly characterization explanation. PC software matched with JPM,JOM proton magnetometer is developed, achieves initial processing results.In this paper, based on industry standards and actual experience, the content andthe methods of instrument checks are summarized, including instrument noise level,observation accuracy, system errors, consistency, opinions on handling the existinginstruments are also explained; the article then describes the short-term variation ofthe magnetic field, discusses the daily change observations and diurnal correctionmethod applied to PC software; starting from the introduction of Gaussian sphericalharmonic analysis mode, the article goes on to describe the theoretical basis andpractical ways of gradient correction by using the IGRF model; using the commonWGS-84latitude and longitude coordinates turn Beijing-54plane coordinates as anexample, the article studied the typical coordinates transform problem according to the calculating steps, including converting from different ellipsoid datum andcoordinate projection etc., in order to solve the theoretical barriers of programming;the paper then qualitatively studies the magnetic anomalies from different magneticlatitudes typical target body based on the simulation results of the local geomagneticfield model, and how the target material, the depth of the anomaly influence thecurve, building a foundation for quantitative interpretation; the article finallyintroduces the design ideas and functions of the PC software JEMLab developed onwindows platform and uses the function of calculating diurnal correction and IGRFas an example to show the preliminary results of data processing.