This page explains the test criteria that was used to test the avalanche transceivers. I strive to make the tests as scientifically accurate and unbiased as possible.

Range Testing

The range chart summarizes the results of multiple test sessions over several years. In a recent session, I tested a whopping 53 transceivers that included 15 different makes and models. All of the test sessions follow the same basic criteria:

• There were not any overhead or buried utility lines. (We listened with an analog transceiver for background signals. Occasionally, a faint radio station was heard in the background. These tests do show a digital transceivers ability to filter out background noise and did not effect the range test results materially.)

• The tape measure was non-metallic.

• There were no metal poles or wires nearby.

• All transceivers had new batteries (the same make and model purchased at the same time).

• In the case of digital transceivers, the distance recorded was the point where the testers agreed the transceiver had locked on to the signal. That means the transceiver was consistently displaying both the distance and direction indicator (an occasional missed beep was acceptable).

• In the case of analog transceivers, the distance was the point where the sound was "faint but undeniable." This required a very quiet background--you would never hear the faint signal over the sound of moving skis (or even while walking on snow). This makes it a little unfair to compare the analog distances (which required total silence) to the digital distances (where the background noise was immaterial). Due to the subjectivity of when the signal was "faint but undeniable," differences of less than 5 meters are probably insignificant.

• The distances displayed on the screen of the digital receivers is an estimate of distance to the transmitter following the flux line rather than a straight line between the transmitter and receiver. Most digital beacons display a distance that is greater than the actual distance. In all cases the actual measured distance, rather than the distance displayed by the digital beacon, was recorded and is displayed in the range chart.

Range Tests Sessions

1. Session #1 took place on January 15, 2004. The air temperature was approximately 18^F (-8^C). The ground was covered with approximately 6" of snow. The transmitting transceiver was an Ortovox M2 placed on top of the snow. Five beacons were tested.

2. Session #2 took place on January 17, 2006. The outside temperature was approximately 25^F (-4^C). The ground was covered with approximately 3 meters of snow. The transmitting transceiver was a Pieps DSP placed on top of snow. Seven beacons were tested.

3. Session #3 took place on January 18, 2006. The conditions were similar to Session #2. Four beacons were tested.

4. Session #4 took place on February 27, 2006. The outside temperature was approximately 50^F (10^C). Three beacons were tested.

5. Session #5 took place on October 24, 2006. The outside temperature was approximately 65^F (18^C). The test was done in a city with some background noise (a faint music radio could be heard). The surface was a lawn. The transmitting transceiver was an ARVA Evolution+. The six transceivers tested had an average increase in range of 50%! Whether the increase was due to the transmitting beacon (an ARVA Evolution+), the temperature or other environmental conditions, these values were not averaged in with the preceding tests. Six beacons were tested.

6. Session #6 took place on November 12, 2006. This was a remote area in the mountains. The air temperature was approximately 26^F. The ground was covered with approximately two feet of snow. The transmitting beacon was a Tracker placed on top of the snow. Ten trained rescuers tested 53 transceivers at this mother-of-all-tests.

7. Session #7 took place on December 5, 2006. During range testing, the outside temperature ranged between 23^F and 26^F. The ground was frozen dirt with approximately 2 inches of snow. For performance and spike testing, the temperature was approximately 33^F and the ground was covered with two feet of snow. The transmitting beacon was an Ortovox M2. Nine beacons were tested.

8. Session #8 took place on December 27, 2007. The outside temperature was approximately 22^F. The ground was covered with approximately 12 inches of snow. The transmitting beacon was a Tracker DTS that was inline with the receiving beacons. Eight beacons were tested.

9. Session #9 also took place on December 27, 2007, but at a different location. The outside temperature was approximately 15^F. The ground was covered with approximately three feet of snow. The transmitting beacon was a Pieps DSP with v5.0 software. Nine beacons were tested.

Many variables influence how close a transceiver must be before it detects a signal. The signal is strongest when the antennas of both transceivers are aligned. The ranges published on BeaconReviews.com are when the transceivers were physically aligned. (In many tests I also recorded the antennas in worst case, i.e., perpendicular, orientation, but I have not published that data.)

Multiple Burial Testing

My typical multiple burial test involved two transceivers placed approximately five meters apart. The searching transceiver was then changed to search mode (sometimes within the receiver's range where it would immediately pick up a single and sometimes from a distance where no signal was received). This process was repeated using two transmitting beacons of the same brand (without signal overlap), using two transmitting beacons with different rates (periodic signal overlap), and using two beacons using the DSP's Smart Transmitter (different brands, without signal overlap).

The "suppress" functions were used to see if the searching beacon would consistently suppress the victim's beacon and if the searching beacon would direct the searcher to the next victim.

My multiple burial testing has been limited to two transmitters.

Spike Testing

To test if a transceiver can ignore spikes, the transmitting beacon was placed two and three meters above the ground on a non-metallic pole (this is easier than digging a three-meter hole). Tape measures were run from the base of the pole in opposite directions on the ground. The receiving beacon was then moved slowly along the ground, in a straight line, to search for the strongest signal(s).

This test was repeated during several sessions, using different transmitting beacons, at different heights (usually two and three meters). The orientation of the two transceivers plays a large role in the location of the spikes, but the results were very consistent based on the number of antennas (the exceptions being the Ortovox X1 and D3 which are three-antenna transceivers but which did not eliminate spikes in my testing).

Transceiver Weight

The weights listed in the comparison table are the actual weights including batteries and the harness. The volume of the transceivers was calculated based on the length, width, and depth specified by the manufacture. Certainly lighter, smaller, transceivers are preferable. 

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