Recently, We’ve come across an explanation from BeaconReviews.com of how some types of avalanche beacons, during deep burials, could lead you to probe up to a meter or more away from the actual victim.
It has to do with signal spikes from the flux lines of the transceiver.
“The distance between the strongest signal and the transmitter is based on the orientation of the two transceivers and the depth of the burial. These possibly confusing signals are the result of the flux lines and are called spikes.” — BeaconReviews.com
When a transmitting transceiver is on the surface (or just below), a receiving beacon will always show the shortest distance directly above the victim, regardless of the orientation of the two beacons. This changes, however, with deep burials.
When/if the receiving beacon has only two axis antennas and is horizontal, and the buried transmitting beacon is vertical and 3 meters deep, the strongest signal will be picked up a meter OR MORE away from the actual burial point of the victim.
According to BeaconReviews.com with standard probing technique, narrowing down this area could take up to 5 minutes. In the event that one of your buddies is stuck under 2-3 meters of rock hard avalanche snow, you definitely do not have 5 minutes to spare.
“The actual distance between the strongest signal and a point directly above the victim depends on many factors (primarily the depth and antenna orientation). In my spike testing, the average distance from the strongest signal to the point over the victim was 0.55 meters (21 inches) on one-meter burials, 0.85 meters (35 inches) on two-meter burials, and 1.4 meters (four feet) on three-meter burials. (This was with the transmitting beacon in a vertical position and the receiving beacon in a horizontal position as shown above.)” – BeaconReviews.com
It gets more complicated. When both the transmitting and receiving beacons are horizontal, the strongest signals occur directly over the victim and a meter or more on either side.” — BeaconReviews.com
For a more detailed explanation of this phenomena as well as an easy method of testing if YOUR beacon is affected by these spikes, visit Beacon Spikes at BeaconReviews.com