The specs of this sensor module give a resolution of 15 nT but there is no indication on the SENSITIVITY.
The resolution is based on the counts of periods when using the highest clock rate (Period Select = 4096). In this setup, a single count has a value of 15nT. This is indeed the resolution.
However, where is it defined that the sensor is giving ONE more count when there is exactly 15nT more? This would be the sensitivity.
Also, the linearity vs temperature seems to be very good but the plots are not detailed enough to clearly see what happens between 30000nT (30?T) and 60000nT (60?T) which is the range of earth magnetic field all over the world.
This is the 'trick' used by all those manufacturers of that type of sensor. They express all the units in Gauss or in ?T. Then, giving a resolution of 0.015?T seems to be very precise but it is not so when you want to use those sensors to measure the weak earth magnetic field with a reasonable precision.
If this 3-Axis sensor is really able to precisely measure field gradients by steps of 15nT and if it is rather insensitive to temperature variations, then it should be a better solution than the famous and well-known FGM-3 fluxgate sensors since those only give a single vector and are quite sensitive to temperature changes. This is still not at the level of a PPM but I think a gradiometer configuration based on those sensors would be useful in the field.
I like its SPI interface and its price, that should be easy to make some experiments for those who would search for an alternative to the FGM-3.
Willy
One obvious advantage of a 3-axis sensor is that the total magnetic field value can be calculate from the three vectors. As a consequence, there is no more difficulties in aligning the sensors of a gradiometer as it is with the FGM-3 and in respecting a precise orientation of the survey lines and the sensors.
Willy
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