GA-52CX Calibration??

[Orbit]

When it rotates in free space? If you adjust the sensors when the pipe is horizontal with that and the pipe is in a position for example north south! Any rotation in other directions will cause a decrease or increase in the frequency output on the sensors! Specifically, I mean fgm 3.The same happens with the flc 100 or a copy of the ems 100 or some sensors that I bought from Great Britain and are used in the gpa 1000. However, depending on the change, it can be done in hardware or software to do something like geb balance, I specifically did that on the hardware, for example, the input to the processor expects 500mv, that hardware accessory always sets the input to the expected 500mv when I press the button. From 500mv it can go to 0v or up to 5v plus when it finds anomalies. Gpa 1000 does it softer. I did that let's call it a geb balance with flc 100 sensors that give a dc voltage at the output. It seems to me that I got the best performance and the most stable operation when the sensors are placed horizontally 50 cm apart.

[Carl-NC]

I can't explain it because it depends on the mag design. But, ultimately, you want the mag to have no response when it is rotated in free space. A little like GB, kinda sorta.

[Daves]

I would use a bar magnet to measure sensitivity, I personally use a cow magnet. Flip it end-over-end and see how far away it can be detected. Compare to a known good unit.

Most magnetometers (and I assume GA-52CX) are dual-sensor gradiometers. There is probably a calibration method for aligning the sensors which might be mechanical, circuit-based (e.g. trimmer), or software-based. If you are away from any iron metal and you rotate/roll/flip the mag in free space it should not respond to Earth field. If it does, then the sensors need alignment calibration. If it does not, and sensitivity is consistent with a known good unit, then you shouldn't need to do anything.

Hi Carl,
what is the "alignment calibration" how do you define and explain this? Like ground balance in detectors?, I would appreciate it if you could explain it.

[Carl-NC]

I would use a bar magnet to measure sensitivity, I personally use a cow magnet. Flip it end-over-end and see how far away it can be detected. Compare to a known good unit.

Most magnetometers (and I assume GA-52CX) are dual-sensor gradiometers. There is probably a calibration method for aligning the sensors which might be mechanical, circuit-based (e.g. trimmer), or software-based. If you are away from any iron metal and you rotate/roll/flip the mag in free space it should not respond to Earth field. If it does, then the sensors need alignment calibration. If it does not, and sensitivity is consistent with a known good unit, then you shouldn't need to do anything.

[Altra]

It's really hard to test any kind of magnetometers around buildings. Probably the best test would be some area away from people and trash. Using standard iron items for test targets. Reading some of their patents, most of the calibration takes place at the factory with careful alignment of the two sensors. I have not tried to pull the sensor assembly out of the tube yet!

[bklein]

I have restored a few of these and can’t tell if calibration is necessary or not - I don’t know what a good test for it would be. I don’t notice a difference between units just sensing random ferrous targets around my home.

[Altra]

What problem are you having or why do you want to calibrate it? One of the trimmers is for tx frequency. Another trimmer, I believe sets the audio null/threshold for no signal. The third is connected to the transmit circuit not sure if it adjust output level or some kind of distortion adjust? I have not had time to reverse my pcb.

The manual states the idle audio frequency is 40Hz

[bklein]

Anyone have an understanding of the calibration procedure for the GA-52CX?