SAM Frequently Asked Questions
Q1. Can the FGM-3h magnetic sensor be used with the SAM?
A1. Yes, the -3h sensor can be used with the SAM
and is entirely compatible with it. However, there are at least a couple
Q2. What are the resolutions of the FGM-3 and -3h sensors?
A2. The resolutions of the -3 and -3h are the same, around 1-2 nT. The -3h signal output characteristics are the same as the -3 and is compatible with the SAM. However, you will need to adjust the offset and correction in SAM_INI so that your data values are of the correct magnitude.
Q3. Is the FGM-3h sensor available as an option?
A3. The FGM-3h sensor is not listed in the price list but is available as an option. Please contact us for price and availability.
Q4. Does the magnetic sensor require a separate power supply?
A4. You do not need a separate power supply for
the sensor. The same +12 vdc power supply that runs the main controller also
runs the sensors. Note that the kit does not come with an ac adapter power
supply but one is available as an option for North America. In almost all SAM
systems, the sensor is powered from the main controller through a 3- or
4-conductor cable, (1) lead for common ground, (1) lead for power and (1) lead
for each sensor output signal.
Q5. How many sensors does the SAM support?
A5. The original SAM hardware and software fully supports two sensors. The SAM-III released in 2010 supports three sensors. The original SAM main controller PCB has space for the logic circuits associated with a third sensor. A conversion kit is available.
Q6. Can the sensors be mounted anywhere?
A6. The sensors can be mounted anywhere as long
as they are away from artificial magnetic fields. However, there are a number of
considerations, three of which are described here. For additional information,
download the SAM Construction Manual:
Q7. In a 2- or 3-sensor installation, do the sensors require separation?
A7. The following information was provided by Darrel Emerson, who performed some undocumented testing on the FGM-3 sensors. If two sensors are parallel and too close, they tend to pull each other onto the same frequency. In the parallel configuration, it is recommended that the sensors be separated by at least 150 mm (6 in.) to minimize this effect. If the two sensors are at right angles to each other, the pulling effect is much smaller. The effect also depends on the alignment with the Earth's field. If the sensors are parallel, but one is rotated 180 degrees (so the pins are pointed in opposite directions), then for most alignments with respect to the Earth's field, the two sensor frequencies are quite different, and the pulling effect disappears. However, when their alignment with the Earth's field brings them both to nearly the same frequency, the frequency pulling effect is strong. Users are encouraged to perform their own experimentation and report their results to the SAM-International Yahoo Group.
Q8. How much does the SAM cost?
A8. Click here for a price list and ordering information.