There are several projects currently in the works.  Geometrics has solutions and more are emerging as we produce the first commercially available UAV magnetometer systems.  Here are some notes on the process and procedures.

At this time the only magnetometer available in the industry that can do this job is the G-823A or B.  For this project we would recommend the B as it does not come with heading error spec and is about 5K cheaper.  The BWL means without Larmor (sine wave) output for external counter.  No need for an external counter when there is an internal counter.
 
Why, you say, should we provide a magnetometer without heading error specs? The reason is that any small unmanned aerial vehicle (UAV) probably has magnetic components and on a small aircraft, the sensor cannot get very far away from these parts.  Or at least some care must be taken to make sure that the magnetic qualities of UAV are minimized.  This is sort of an art but it can be accomplished by removing steel parts and replacing them with aluminum, or brass, or composite or stainless steel or titanium.

The 823B requires 1 amp on start up at a minimum of 24 VDC.  Then after a few minutes (maybe 3 minutes depending on outside temperature) it is ready to go.  At that time it will only draw about 500 ma of current or about 10 watts.

The sensor and electronics bottle weigh 2 kg.  (Note: next year we hope to be able to offer the MFAM which is a much smaller magnetometer, at 0.5kg, 2.5 watts with 10 hz sampling and 10pT/rt Hz sensitivity.  Projected availability is end 2010.)

Data is output via RS-232, typically at 10 Hz.  There is no data system associated with the 823B.  In the future we hope to offer a combined magnetometer and data system or UAV use, perhaps next year.
 
Besides the magnetometer, the data logger should record GPS and also altitude above ground.  Another useful tool is to record a three axis fluxgate for yaw, pitch and roll information.  This would then be used to remove the magnetic effects of the platform.  This may be the most essential feature of the survey features.

Compensation reduces the effect of the motion of the platform from ferrous materials in the aircraft.  These materials could be in the engine, landing gear, control surfaces or even caused by the electrical currents running the data logger or the magnetometer!

A sophisticated program such as MagComp is required to remove these motion effects of remanent, induced, eddy current and electrical current.  Right now our software does all of these things except electrical current.  We are going to being working on the electrical current compensation functionality in the next few months.
With properly implemented compensation, the platform (the fixed wing or helicopter aircraft) "disappears" magnetically, allowing us to see very small targets on the ground.  The improvement ratio (IR) can be as much as 10 or more. However, it is not required if the aircraft is very clean magnetically. 
Therefore, MagComp is normally offered as "Optional". Because the software requires training, two days are offered with the program along with the small orientation Fluxgate (applied physics model 539).  Note if compensation is used, the data logger will need to record 3 serial inputs, mag, GPS and fluxgate.

Please request a quotation for the 823B and for optional MagComp (including fluxgate).  You will need to supply the GPS and also to consider whether to log the data on the UAV or telemeter it to the ground.  Telemetry means you can use a full size computer to log the data, and you don’t have to carry the weight of the data logger.  However, you must concatenate the data from the GPS and mag on the aircraft before transmission (add them together).  Also if the transmission link drops out (the radio link is broken because the aircraft goes behind trees for ins