Avvy beacon

[fleblebleb]

GPS can't get you millimeter accuracy. More importantly, the signal is very easily blocked and distorted, by roofs, cliffs, trees, probably even cloud cover although I don't know for sure.

 

Here's a link to the home page of a Ph. D. student at UW who works on fine-grain location technology.

[mattp]

Snowboy -

The pie charts compared "with" to "without" beacons, but did not address whether or not the "with" victims might have had a hand or piece of clothing or something exposed (so in these cases the beacon wasn't necessarily a help). I bet further research would reveal that the "with" victims were travelling with companions who knew how to rescue their buddies or were otherwise more likely to be in situations where recovery was more likely.

 

I'm not saying don't use the beacons, but I'm just questionning the idea that the pie charts show that beacons make you safer. Food for thought. I apologize if this is a rehash of what I've asserted before.

[allthumbs]

You'll need differential capability to get pin point accuracy. It's available as an option, but it's a bit more $$$.

[snoboy]

The pie charts compared "with" to "without" beacons, but did not address whether or not the "with" victims might have had a hand or piece of clothing or something exposed (so in these cases the beacon wasn't necessarily a help). I bet further research would reveal that the "with" victims were travelling with companions who knew how to rescue their buddies or were otherwise more likely to be in situations where recovery was more likely.

 

Great points mattp. I would guess you are probably right on about the beacon'ed travellers being with people who new how to rescue them. But that is part of the point isn't it?

 

I would guess that the hand or piece of clothing wasn't an issue though, as the article is about transceiver effectiveness, and concludes that transceivers are effective.

 

I don't think they make you safer in any way. It just seems that they might improve your chances if you should f%#$ up.

[Dru]

The actual John Baldwin quote, according to the VOC Journal c. 1976, is "The only way to escape the whiteout is to BE the whiteout". I misremembered it as avalanche and thought he was talking about straightlining it downhill.

[iain]

This is irrelevant info for the topic, but Differential GPS doesn't get you much these days. We used to have a subscription for FM corrections in MN and it was expensive, but that was before SA was turned off. We usually just post-processed uncorrected data back at the lab, which is more accurate than live corrections anyway, and is free. Out here you can use the USCG beacons though, which are free, but with SA off, it isn't much of an improvement.

 

CMT Z33 System

 

Here is the unit we were using, though it is not technically "millimeter" accuracy, 1cm realtime with post-process static corrected data at 5mm + 1ppm is good enough for most people! The backpack makes it a little inconvenient for the EPA stream surveys we were doing but there's some really killer featuring options with ArcInfo with these units. Unfortunately they use Winblows. So yes you can get very accurate with GPS, despite what the naysayer above says. It just takes a little while and is fairly worthless for avalanche rescue.

 

Back to avalanche beacons...

[fleblebleb]

That's pretty cool, centimeter accuracy is an order of magnitude better than I thought they could do. It's still an order of magnitude worse than millimeter accuracy but that's hair-splitting.

 

The price tag makes it somewhat irrelevant though, eh? Anywayz, you're right, that's pretty cool technology, I'll shut my naysaying mouth and stop crossposting

[Beck]

Okay, i'm thinking this thru and wondering if you all are, as well.

 

sure, a GPS with 1cm accuracy will tell you where YOU are, but is it going to tell you where the Victim is buried? The units would still have to communicate to each other, and satellite transmission technology to allow for satellite bounce isn't anything that's going to be inexpensive, compact, or run on AA batteries... to do short distance communication, a radio wave is the way to go, and it is going to be a LONG TIME before there's even this type of GPS cross communication thing going on... what will probqably happen in beacons, is a CPU capable of transcecting the flux lines, correlate it with a grid, and get you right to the victim without the user following a flux line. I doubt GPS is functionable under a snow load.

there is still going to be an offset factor on deep/steep variables, so keep in mind to dig uphil of where you think the victim is buried....you should try for a probe hit before digging anything.

 

remember, practice with your Beacons.

"Run, run, run the grid;

then pace, pace,stop, sweep, sweep- follow the flux, repeat."

[iain]

Iain said:

It just takes a little while and is fairly worthless for avalanche rescue.

I repeat, GPS is fairly worthless for avalanche rescue.

[iain]

GPS certainly won't function under snow, as anyone who skis through our snow-laden trees knows. Fun facts: the signal is almost completely eclipsed in the first millimeters of water if placed underwater (it is around 1.6 GHz, readily absorbed). This is one of the reasons trees are cut down around those microwave reflector boards and towers, and why your coffee can be reheated so easily with microwave energy.

[thelawgoddess]

hey iain. why didn't you just start a new topic thread?

[iain]

I'm not very bright at times...and it's probably not very interesting for a bunch of people (so why'd I post it? I know) happy holidays goddess.

[Pencil_Pusher]

A day late and a dollar short again!

Took a Gary Brill avalanche course two years ago. I have two Ortovox transceivers, the ones that ping like sonar and have three led lights. Anyhow, this sucker is pinging away long after everyone elses went silent as Gary walks way out there. It's still pinging as he turns around to ask if that's far enough. We had an assortment of newer Ortovoxes, Trackers, Pieps and such... mine's the only one still giving off a faint beep. Long and short, when we went out en masse, we used the Ortovox on point to first locate the signal and then get the Trackers on course to expedite recovery. I like my Ortovox and also understand the simplicity of Trackers for newer hands... maybe it's just the practice thing emphasized throughout this thread.

Just make sure your buddy has the best shovel!

Good thread, I enjoyed reading through it. For whomever wants the super, in-depth coverage of avalanche territory, Gary Brill does an excellent job of it, if you can keep up with his mindset. Alot more than my pea-brain could process at one sitting.

[ryland_moore]

Hey iain, I need to talk to you about specific GPS units. Call me at my office 541-345-2799 . Need to talk to you about WAAS Trimble Geo XT and other options that are hopefully less than $6k.

[fleblebleb]

For the price of one digital beacon you can get two analog ones, which means you are self-sufficient for practicing. That's kind of cool...

 

Woo-hoo! Made an on-topic post

[snoboy]

$385/2 does not equal $295

 

For the price of one digital beacon you can get two analog ones,

[dbconlin]

Does anyone know WHY digital beacons have less range than analog?

[snoboy]

Does anyone know WHY digital beacons have less range than analog?

 

Well, here is an answer from the Backcountry Access website. Some good reading over there!

 

This is copied from this article :

 

For all types of recievers, extensive filtering and processing (e.g. mixing) is done to reduce this extraneous noise and to help isolate the beacon's transmission signal, which gets very weak quickly from the transmitter. This partially explains why so called analog receivers appear to have more receive range: with analog transceivers, this filtering is done by the user's ear rather than the transceiver's microprocessor. Consequently, the usefulness of thi weak signal at long range is heavily dependent on the ability level of the user.

 

This difference in receive range is due exclusively to the noise filtration process of the digital receiver, and has no relationship to the munber of antennas used in receiving the signal as suggested in other literature.

[Beck]

to put it in laymans' terms;

avy beacons are, essentially, radio transmitter/receivers.

 

a straight analog beacon receives the target beacon signal just like a radio picking up radio stations, and a digital beacon will have less range and sensitivity, just like having a digital radio tuner on "seek"- they never can pick up as many stations than when you flip thru the channels manually. Having a digital processor do the "listening" for you limits the sensitivity, and hence, the range.

 

[snoboy]

As usual I geek out, and Beck comes along to put it all in layman's terms.

 

Nice job, you said it better than I could (obviously).

[dbconlin]

ok, thanks to both, snoboy and beck.

So, there isn't anything inherent in their ability to pick up the signal (or transmit it), but it is just the processing of that signal that reduces range, yes? So beacons that start off in analog and then switch to digital, such as, I beleive, the Mammut Barryvox (and the X1, maybe???) can do would eliminate this problem. Sounds like the perfect solution!

Am I wrong, somehow?

[Beck]

yes, Db , that is the intent of ana/digi transceivers like the Barryvox and the x-1. There are significant differences between the two however...

[gregm]

somebody was really trashing the new ortovox x-1 over on telemarktips.com. whoever it was he apparently has a business selling nothing but beacons and went out and tested the x-1 next to other beacons and found the range deficient among other problems. obviously just one person's experience though...