【FAQ】Electromagnetic method product knowledge

Which instrument is more accurate, a single-channel instrument or a multi-channel instrument?

What is a single-channel instrument? What is a multi-channel instrument?

Which is more accurate, a single-channel instrument or a multi-channel instrument?

Requirements for the direction of survey line layout？

The principle of geophysical survey wiring is generally to lay the line perpendicular to the direction of the abnormal body. The general principle of groundwater detection is to lay the line perpendicular to the direction of groundwater flow. Assuming that the direction of groundwater flow is east-west, the best direction for wiring is north-south. When the width or position of the waterline cannot be determined, increasing the length of the survey line is undoubtedly the best choice to find the waterline position.

The difference between electromagnetic probe and electrode measurement？

Electromagnetic probe measurement does not require wire pulling, and the probe point is located directly below the probe; the electrode rod measurement point is located at the center of the MN electrode rod. The electromagnetic probe measures the resistivity by converting the magnetic field into an electric field signal, while the electrode rod measures the resistivity directly by measuring the electric field signal. In some areas, there will be completely opposite abnormal reactions.

What are the grounding requirements for the probe and electrode rod?

Which is more accurate, wireless probe measurement or electrode rod measurement?

What are the external interference factors that affect the accuracy of the measurement data?

When measuring a known well, why does the measurement result show that there is no water?

What does the measurement point increment mean? How to set it?

The measurement point increment is the interval between measurement points when the mobile phone is mapping, and does not represent the point distance. The larger the measurement point increment is set, the wider the graphic display is. Generally, for instruments with a depth of 30-200 meters, the default measurement point increment is 10, which is better. For instruments above 300 meters, the measurement point increment value can be appropriately increased according to the instrument’s detection depth, such as 20 or more. For the convenience of map recognition, it is recommended to set the measurement point increment in multiples of 10. The setting of the measurement point increment only affects the width of the graphic and will not affect the measurement accuracy of the instrument.

How to deal with wires, metal objects, etc. during measurement?

If you encounter high-voltage wires, wires and other power facilities on the ground, it is best to stay away from them, especially high-voltage wires. It is best to stay away from them for more than a few hundred meters. If you cannot stay away, measure parallel to the wires and high-voltage wires as much as possible, and each measuring line needs to be measured more than 2 times to find the common abnormal area of 2 color maps. Improper measurement and handling in places such as high-voltage wires and wires will cause inaccurate measurement data due to excessive electric field strength nearby, and the geological information displayed in the color map will be distorted, misleading users to make wrong judgments. For small underground metal pipes and metal objects, it has little effect on the measurement results; for relatively large metal objects, it will form a certain low-resistance shielding on the natural field; reduce the detection depth of the instrument. If the metal pipe is charged, it will generate electromagnetic interference, resulting in inaccurate measurement data, so it should be kept away.

What are the grounding requirements for probes and electrode rods?

What is the difference between electromagnetic probe (no need to pull wire) and electrode measurement?

The electromagnetic probe measurement point is directly below the probe; the electrode rod measurement point is the center point of the MN electrode rod. The electromagnetic probe measures the resistivity by converting the magnetic field into an electric field signal, while the electrode rod measures the resistivity directly by measuring the electric field signal. In some areas, there will be completely opposite abnormal reactions.

What are the requirements for the layout of the survey line?

The principle of geophysical survey wiring is generally to lay out perpendicular to the direction of the anomaly. The general principle of groundwater detection is to lay out perpendicular to the direction of groundwater flow. Assuming that the direction of groundwater flow is east-west, the best direction for wiring is north-south. When the width or position of the waterline cannot be determined, increasing the length of the survey line is undoubtedly the best choice to find the waterline position.

How to deal with electric wires, high-voltage wires, network cables, underground pipes, metal objects, etc. during measurement? What interference will it have on the measurement results?

If you encounter high-voltage wires, electric wires and other power facilities nearby on the ground, it is best to stay away from them, especially high-voltage wires, which are better to stay away from them for more than a few hundred meters. If you can’t stay away, measure parallel to the electric wires and high-voltage wires as much as possible, and each measuring line needs to be measured more than 2 times, looking for the common abnormal area of 2 color maps. Improper measurement and handling in places such as high-voltage wires and electric wires will cause inaccurate measurement data due to excessive electric field strength nearby, and the geological information displayed in the color map will be distorted, misleading users to make wrong judgments. For small underground metal pipes and metal objects, it has little effect on the measurement results; for relatively large metal objects, it will form a certain low-resistance shielding on the natural field; reduce the detection depth of the instrument. If the metal pipe is charged, it will generate electromagnetic interference, resulting in inaccurate measurement data, so it should be kept away.

Which is more accurate, electrode rod measurement or wireless probe measurement?