Digital avalanche transceivers (beacons) display the distance and direction to a buried avalanche victim. They also output audio tones to aid in the search. Analog transceivers, and transceivers with only one antenna, provide a subset of this information.
When searching with a old-school analog beacon, the only indication you had that you were getting closer to the transmitting beacon was an increase in volume. The pitch and cadence (i.e., the rhythm) remained constant. You were simply listening to the "beep" that was being transmitted by the buried transceiver. Because it is difficult for humans to identify subtle changes in volume, analog transceivers allowed you to turn down the transceiver's sensitivity.
Digital beacons changed all that. Rather than broadcast the received beep through the speaker, they generate an audible tone based on the strength of the signal. Most (maybe all) digital transceivers increase the cadence of the tone (i.e., beeping more frequently as you near the victim). Many digital beacons also increase the pitch of the tone. The combination of increased cadence and pitch is easily recognized by humans.
A few transceivers, including the Mammut Pulse provide the option of a digital signal (increasing the cadence, pitch, and volume) or an analog signal (by broadcasting the analog tone). The analog tone can be very helpful when dealing with multiple victims.
The Mammut Pulse emits an analog tone during the
signal search (where you may be able to hear a very weak signal)
and then switches to digital (with a smooth increase in both the cadence and pitch). My fellow testers and
I feel that the Pulse's audio feedback is outstanding.
The Mammut Element, Pulse (beginning with version 3.2), Barryvox, and Barryvox S include a feature called "directional tones." When enabled, the audio tone changes when the direction indicator changes. This reduces the need for you to stare at the direction indicator as you work your way toward your buried partner during the coarse search. (Directional tones are only available in the Pulse and Barryvox S when using digital, rather than analog, audio.)
Most old-school single antenna transceivers indicated the distance to the victim using either a series of lights (e.g., green, yellow, and red). All multiple-antenna digital beacons display the estimated distance in meters.
Transceivers display a minimum distance of somewhere between 0.1 meter and 0.3 meter. The smaller minimums are only significant when you are searching for a transmitter that is buried under less than one foot of snow (as might be the case when practicing).
The distance that is displayed is an estimate of the distance along the flux line rather than the actual distance directly to the victim. The range charts and distances mentioned on BeaconReviews.com are the actual measured distances.
Transceivers with more than one antenna display a "direction indicator" that aligns the searching transceiver with the flux lines that are being broadcast by the victim's transceiver. Single-antenna beacons cannot display a direction indicator.
On some beacons the direction is displayed as an arrow whereas other beacons use five lights, three lights (the Ortovox X1, Ortovox Patroller, and Ortovox D3), or a grid (the Ortovox S1). The Mammut Pulse's arrow is unique in that it floats freely like the needle on a compass and can point behind you if you are moving away from the victim. The Mammut Barryvox and Barryvox S direction indicators are unique, because they display an arrow that bends to show you your route along the flux line.
All of the direction indicators are a little inaccurate when they are relatively far from the victim. This causes the direction indicator to jump around. You should average the direction as you advance toward the victim. For example, if the direction indicator jumps between straight-ahead and hard-right, you should average these and head gently right.
When the signal is first received, it is just as likely that the indicator will point you 180-degrees from victim as toward him. You should watch the distance indicator to make sure it is decreasing as you follow the direction indicator. If the numbers are increasing (i.e., you are moving away from the victim), you should turn 180-degrees.
The direction indicators on newer digital transceivers disappears when you get close to the transmitting beacon. That's a good thing, because the indicators get confused when you get very close to the victim—it's analogous to following a compass needle when you are standing directly on the North Pole. The disappearing direction indicator forces you to focus on the distance indicator during the fine search.
If your transceiver does not turn off the direction indicator when you're close to the victim, ignore the direction indicator when you are within a meter or two and focus on the distance indicator.
A row titled "Direction indicator disappears" in the Searching section of the comparison table shows the distance when the indicator disappears. Several transceivers allow you to select this distance via a setting. For example, the Mammut Pulse allows you to select either 3 meters or 0 meters.