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Retiring Old Avalanche Transceivers


Photo: Said the right unit to the left, "Move aside you old drifter. And don't let me catch you around these parts again."

by Chester Marler


Q: Is it time to upgrade your old analog avalanche beacon to one of the new digital wonders?  A: Yes, but the answer is not as simple as you might think.

 

I few years ago I was lucky enough to begin working part-time with a group of young avalanche professionals doing the DOT’s avalanche control work on the Stevens Pass Highway.  Part of my introduction was being handed a new, digital avalanche beacon.  It came with a very handy and comfortable harness, and its weight was minimal, but the controls and visual read-out were unfamiliar, so I chose to use my old Ortovox F1 for the first few missions.  I had confidence in my ability to operate it, and felt I should stay with something familiar should a crisis develop during control work.  This was an OK initial choice, but I could tell from my colleagues’ reactions that I needed to adapt to the new technology, and sooner rather than later—so I did.  I found it easy to use, and the ability to search for multiple burials easily (the marking mode) quickly converted me.

But I still assumed that my old Ortovox F1, while not as versatile as my new Pieps DSP, remained a reliable and excellent beacon.  In this assumption I was mistaken.  My first clue came from a beacon seminar this fall given by the manufacturer to explain the new features of the latest Pieps model.  Part of the discussion was a concern that many of the older analog models—especially the Ortovox F1—were being passed around to newer backcountry skiers by skiers upgrading to digital beacons.  Why is this a problem?  Frequency drift with the older beacons, through years of use and abuse, is causing the frequency to move beyond the +/- 80 Hz tolerance allowed for the 457 KHz band for beacons.  I happened to have my F1 along as well as my new beacon, so I asked the expert to check its frequency in send mode (the advanced digital models can do this quickly).  My beacon had drifted nearly off the edge of the allowed band, almost “invisible” to a modern beacon!  It is now retired.

Beacon facts and considerations:  (based on a selective review of sources)

  • Frequency drift is common with older analog units for two reasons: age and the use of a crystal in frequency transmission.  Drift can occur with digital beacons, but is usually minimal.  But even digital beacons should be checked periodically.
  • Digital units use a more confined frequency—less band slop-over—which helps digital processing, but makes it more difficult for them to detect analog units with a frequency drift beyond the international standard. 
  • Older analog units have a single antenna, which means the strength of the signal is a function of the orientation of a buried beacon.  An unfavorable orientation (termed an unfavorable coupling) gives a reduced signal range.  Three-antenna digital units, where each antenna is on a separate plane, reduces this problem, and also helps in sensing burial depth.  Analog units do have a longer theoretical range, but only if the coupling is ideal.
  • Digital units are easier and faster to use for the non-professional and for those professionals who do not practice on a frequent, regular basis (this includes 99% of us).  This is why manufacturers have embraced digital technology—it works better for most applications and most users.
  • The digital beacon’s wave function in send mode is precise in its on/off nature, whereas the analog wave function has a continuous carrier characteristic.  This means a digital receiver may have difficulty in distinguishing whether a single beacon is one or two devices—one case where compatibility between the digital and analog is not ideal.
  • Some of the most advanced (and expensive) digital beacons also have an analog mode, to satisfy the needs of some users for the infrequent benefits of analog functions. 
  • The Alpine Club of Canada no-longer allows analog and single antenna beacons on its club-sponsored trips.  The Canadian Avalanche Centre recommends recreationists avoid both dual and single antenna beacons.  They also note that 3-antenna digital beacons can locate other digital beacons faster than they can analog beacons.  The backcountry skiing website Wild Snow does not recommend the Ortovox F1 for the typical backcountry user, or even 2-antenna digital beacons like the Pieps Freeride.
  • An important final note--radio frequency interference (RFI) can seriously compromise any beacon, sending or receiving, if skiers are using an iPod or carrying a cell phone that is on.  The only electronic device in the “on” mode while touring should be your beacon.   

Unless you always travel solo, avalanche safety and rescue are social phenomena, and the choice of a beacon reflects this reality.  Digital, 3-antenna beacons now dominate the market, and for good reasons.  Mixed touring groups of digital and analog devices should be avoided.  So….those of us with older beacons should embrace technology and discard our older beacons—discard them for good.  Prices on new models are becoming very competitive.      

 
Sources for additional info:

  • www.outdoorgear.com –great reviews and recommendations for beacon purchase.
  • www.wildsnow.com –best-known backcountry skiing blog—good overview on the beacon market, plus an analysis by Jonathan Sheffty.
  • Google “Obsolescence and Analog Transceivers” by Bruce Edgerly and John Hereford (BCA) and “Avalanche Beacons—Getting the Drift” by Bob Lee.