KNOW YOUR TRANSCEIVER: WHAT EACH BRAND DOES WHEN IT MATTERS

The Technique

1. **Transceivers are not interchangeable, and the differences are not in the marketing brochures.** They are in the manuals, the training-body documentation and the safety advisories, and they show up at exactly the moment you can least afford a surprise: a multiple burial with signals overlapping. This lesson is the behaviour of the common units, drawn from what the manufacturers and training bodies actually publish. **Whatever you carry, read your own manual against this and verify it, because firmware changes and so do models.**
2. **Start with when to press mark, because the doctrine is stricter than most riders think.** Genswein and Eide's ISSW guidance is that marking confirms a subject has been **located by the probe**. So the sequence is: fine search, probe strike, then mark. **Mark after the probe confirms, not before.** Marking on a distance reading alone means you can suppress a signal you never actually found. Specialist marking references also note that every unit requires you to be close, within a few metres, before a mark will take. And build the habit of marking even on a single burial, so the movement is automatic when it matters.
3. **The BCA Tracker family: the mark is designed to expire.** The Tracker4 manual is explicit: suppression of the strongest signal **lasts one minute**, the unit then returns to standard search automatically, and it **suppresses only one signal at a time.** Understand what that means in practice: if reaching victim two takes you longer than sixty seconds, your unit will bring victim one back, and it will feel exactly like your own mistake. It is not. It is the documented design. The manual also states plainly that signal suppression "and other forms of signal isolation are not 100 percent reliable". BCA has told you the limits. Believe them.
4. **The Mammut Barryvox: it tells you when it is blind, if you know the message.** On the Pulse, a "stand still" message means the unit has detected signal overlap and **has no usable information to process.** The documented response, from the Canadian Avalanche Association's AvSAR material, is to stop and wait, usually five to ten seconds, for the overlap to pass. And the critical line: if "stand still" keeps returning, **that is the device telling you its marking will not be reliable and you should switch to an alternate strategy.** The newer Barryvox documentation, as far as we have been able to retrieve it, says the same thing in different form: the more buried subjects, the longer the overlaps, the more limited the automatic isolation, flagged with a flashing distance. A flashing distance is not a glitch. It is information.
5. **Ortovox and Pieps: know the ceiling.** The CAA documented the 2016-era units as resolving up to three signals on their multiple-burial indicators, with the Ortovox S1 offering a "4+" mode that cuts sensitivity right down to about five metres. The S1 documentation also concedes that after a "stop" message the unit sometimes corrects itself when you stand still, and sometimes does not. Older Trackers offered a Special mode for up to four transmitters that the CAA describes as taking "practice and discipline" and being "difficult to use". **The pattern in the documented units: about three signals is where documented confidence ends, and everything past that is technique, not electronics.**
6. **Now the case that should permanently change how much trust you place in marking.** In February 2014 the German Alpine Club issued a safety advisory covering the **Pieps DSP Sport and DSP Pro and four Arva models**: where multiple transmitters were far enough apart that their signals did not overlap at all, marking the first victim silently suppressed the others, so they could not be found. In the advisory's reported wording, **this error cannot be recognised by the searcher.** Pieps shipped a free firmware fix. For the Arva models the advisory prescribed a workaround procedure instead: clear the mark if the display shows CE for longer than three seconds with no additional signals, then resume the normal pattern. Note the shape of that failure: it was triggered by signals being **too far apart**, the exact opposite of the close-proximity case everyone drills. The lesson is not that those brands are bad. It is that marking is firmware, firmware has defects, and **a defect in this function is invisible from the outside.**
7. **Which brings us to the professionals.** Edgerly reports that in guiding exams involving three or more victims, candidates generally **do not use marking at all.** They use signal-strength techniques, micro search strips, precisely because those work regardless of what the firmware is doing. Sit with that for a second: the people examined to the highest standard in the industry, under time pressure, with their certification on the line, choose the method that does not depend on the marking button. **That is the strongest available statement about where trust belongs.**
8. **So here is the doctrine this platform teaches, brand by brand and none.** Mark after the probe strike. Know your unit's specific tell for overlap - the Tracker's silent sixty second return, the Barryvox's stand still, the Ortovox stop. Treat the tell as a tripwire: **the moment marking misbehaves, switch to micro search strips without a discussion**, exactly as drilled in the advanced rescue lesson. And the threshold for treating burials as close together, per the CAA, is more than one signal inside ten to fifteen metres, which is when all of this gets hard.
9. **Two practical rules to close.** First, the DAV advisory that exposed the firmware defect also recommended keeping search strips to a **maximum of twenty metres in multiple-burial rescues**, tighter than the strip width you would run for a single. Second, **check your firmware**. The Pieps side of the 2014 defect was fixed by a free update, which means an affected unit that never visited a service centre still carries it, and every brand ships fixes the same way. If you have never updated your transceiver, that is a job for this week, not for the trailhead.

Common Mistakes

Marking on a distance reading before probing. Fix: the mark confirms a probe strike. Fine search, probe, then mark.

• Reading the Tracker's sixty second return as your own error. Fix: it is the documented design. Suppression expires after one minute and only one mark is held. Plan your route to victim two around that clock.
• Pushing through a Barryvox "stand still" message. Fix: stop and wait five to ten seconds. If it keeps returning, the unit is telling you marking will not be reliable. Switch strategies.
• Trusting any unit past three signals. Fix: three is where documented confidence ends across brands. Past that it is micro strips and discipline.
• Assuming marking failures announce themselves. Fix: the 2014 defect was invisible to the searcher by the advisory's own wording. The only defence is a practised device-independent fallback.
• Running old firmware. Fix: if your unit has never been updated, book it in. A free update fixed a Pieps defect that hid victims, and no brand is above needing one.

The Drill

The brand tell drill. With your own unit and two buried transmitters on safe ground, deliberately create the overlap case: transmitters inside ten metres of each other. Find the first, mark it, and watch your specific unit's behaviour on the way to the second. Time how long before the first signal returns if it does, note the exact message or flash your unit shows during overlap, and rehearse the switch to micro strips the moment the tell appears. Write your unit's tell inside your shovel blade if you have to. The point of the drill is that in a real search you recognise the behaviour in two seconds instead of arguing with the display for two minutes.

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