Magnetics

McPHAR’s magnetometer systems are highly integrated and self-contained, high resolution survey systems for installation on fixed-wing aircraft and helicopters. Available as single-sensor system or as a multi-sensor gradiometer system, they feature real-time GPS navigation / positioning with 1 pps synchronization, and a radar altimeter for measuring the height above ground. A GPS navigation system provides positioning information and pilot guidance.

Airborne High-Sensitivity Magnetometer

The CS-3 offers the highest sensitivity and lowest noise on the market, with automatic hemisphere switching and a wide voltage range. In addition to having the maximum active zone and minimum dead zones, it also maintains the smallest heading errors.

Magnetic Compensation

PEIMAGComp quickly creates a magnetic coefficient file to compensate magnetic data. The source data is the PEI binary data file recorded during a compensation test flight. If the source data is not a Pico Envirotec binary data file, there is a provision to import data from a text file. The input file must contain at least X, Y, Z data from a  3-axis fluxgate magnetometer, raw total field magnetometer data, and X & Y position coordinates for heading calculations. Usually four sets of coefficients are created – one for each of the four cardinal headings. A Tri-Axial Fluxgate Magnetometer measures the aircraft’s attitude during flight, and provides X, Y, Z data for recording by the data acquisition system.These data are then used for the calculation of the coefficients necessary for the magnetic compensation.

Base Station Magnetometers

McPHAR operates high sensitivity Scintrex cesium sensors as well as a number of GSM-19 Proton and Overhauser magnetometers manufactured by GEM Systems Ltd. The CS-3 magnetometers provide high sensitivity measurements (0.001 nT, sampling at 5, 10, 20 or 50 Hz), while the GSM-19 proton and overhauser magnetometers are used for less demanding situations. 

All base stations use GPS time synchronization at 1 second intervals. The CS-3 data is recorded in real time using a Pico Envirotec PGIS-BM base station system, whereas the GSM-19’s use their own datalogger. 

During survey operations, every effort is made to ensure that the magnetometer base station is placed in a location with a low magnetic gradient. In addition, it is sited away from moving ferrous objects, such as vehicles, and electric power transmission lines, such that these sources of man-made noise will not exceed 0.1 nT.

CS-3 cesium magnetometer sensor.	RED trace: magnetometer output recorded during the execution of pitch, roll and yaw manoeuvres. BLUE trace: the same output after application of the automatic compensation. The noise level is reduced to a fraction of 1 nT.