Fluxgate sensor spacing

[kayakpirate]

I am building a mag and have a few questions. Is there more sensitivity the farther the sensors are apart?
What is the benefit of using dual axis sensors compared to single axis?
Has anyone built the "simple magnetic gradiometer" from the Ask The Engineer page from Honeywell?

[John Kusak]

So did you start your fluxgate magnetometer?

[Crowbar]

What type of magnetometer are you building? Gradiometer (1 axis or asbolute), magnetic variation station etc? The sensor base is not so critical, depends on sensitivity.

[epitopios]

Fluxgate sensor spacing

Hi kayakpirate
I have made the Gradiometer , at the beggining i had 1.80 meter distance each other and finally I found that 1.20 meter distance between 2 sensors are ok for me.
The whole theme is to calibrate the sensors , thats my only matter
if someone knows how , even if there is a software programme ,any help is accept hapily !!!!
epitopios

[mrkhrdr]

I recall reading somewhere that the depth of penetration scales with the separation between the sensors in a gradiometer. If you want to detect deeper targets, use more separation, in other words. Of course, deeper targets must be larger, or give a more intense signal in order to be detected at all.
I personally am interested in large targets that are much deeper than any gradiometer arm I could carry, so I'm mostly interested in single-detector systems. Geologists & prospectors do fine with PPM units, so I don't think I need a gradiometer.

[mrkhrdr]

Fluxgate design for small space satellites:

In my online research to find out how fluxgates work in theory & practice, I came across this one-page explanation from the folks at Imperial College, London who are part of satellite space-physics projects, including nanosatellites. I thought the description was excellent. It does a good job of explaining how fluxgates generate a signal of twice the frequency of the input to the driving coil. I'm still looking for a description of how cores were chosen and used, particularly the relationship between the B-H curve of the core and the driving current - i.e. where on the curve is the alternating current cycle placed, and what the magnitude of the latter is compared to the curve. If anyone has a reference that explains this, I'd appreciate it if you would share it with me.

http://www3.imperial.ac.uk/spat/rese...afluxgateworks

[ivconic]

For Archaeological surveying in the past; 1m spacing was taken as some sort of "standard" .
Later it was discovered that 0.5m will do fine too.
Theoretically there is a sense in claim that more spacing provides you more depth, but in practice it is not the case.
But as said; that mostly depends on exact type of surveying you are interested in.
For Archeology (shallow soil layers up to 3m) 0.5m spacing will do just fine.
Sampling... in this particular case sampling is taken in range 25cm to 50cm.
I made my grid cells 40x40cm as standard for my type of surveying and local soils.