 Poster: A snowHead
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Any experienced avalanche people here tried out google latitude. I was testing it out home & its amazingly accurate ie down to within a few meters. OK its no replacement for avi gear but I'd be interested to know if anyone has experimented with it??
It uses a gps signal that is then broadcast to anyone you wish also with latitude, works on android & I think there is an Ihone equivealnt too. Apparently gps signals work under a snow covering to some depth.
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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This sort of thing has been covered in other threads here that I'm far too lazy to find right now (and probably contain me ranting in a mildly embarassing way).
Short answer: no.
Medium answer: "a few metres" is best case, and it is likely to be much, much worse. You won't have to be buried very far to have a very poor signal indeed, and if the phone is underneath you then the odds are good that you'll have no signal at all. GPS tracking combined with a continuous data connection absolutely devours mobile phone battery life, so there's no guarantee that it'll work when you need it, and you may not have enough juice to use your phone as a phone to call for help, either. It won't work if you're in a signal blackspot. I could go on, but I'll start to rant 
Even if everything works perfectly, I doubt it'll help you get from where you are to where they are any quicker than a decent beacon.
Ultimately, beacons are by far the best solution, and are likely to continue to be for a good few years to come and mobile phones are no solution at all, and are unlikely to ever be one.
Last edited by Obviously A snowHead isn't a real person on Wed 2-01-13 22:06; edited 1 time in total
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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Cptsideways, the GPS signal may get to the phone I guess the question is weather the phone signal will make it out from under several feet or even meters of snow, only way to find out would be to burrie one and see I guess
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Serriadh, wasn't one of the other points about phones vs. beacons that beacons are usually more securely attached to the body than a phone might be and you wouldn't want to expend effort chasing a phone that had been torn off of someone rather than the victim's body.
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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I'm a little more sanguine about that... beacon harnesses aren't essential.
Have a look at Outdoor Research's take on this particular thing. There's also a guy called Manuel Genswein who appears to be a bit of a beacon guru who's own research suggests that keeping your beacon in a secure trouser pocket is perfectly reasonable, as if your trews get torn off in an avalanche you're unlikely to survive anyway, but I can't track down that particular reference right now.
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NO.
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Amazing that people sign up for services like this, full stop. 'Off Grid' grid is the only way I tell ya. Ba humbug.
Cptsideways, Too many variables for such a critical function.
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AndAnotherThing.., in fairness it's just giving you access to information mobile companies already have about you. There's a great TED talk somewhere about a guy who sued his phone company in order to get access to all the information they had on him and it was astonishing.
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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Timmaah, That's not strictly true - your actually giving a 3d party access to that information.
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Cptsideways, I think there's some mileage in looking at this further. The main criteria are going to be an adapted 'receive' function, increased signal strength, battery power/life and ariel size. If all of these are addressed, I don't see why a mobile should not equal or better a transceiver, especially for helicopter searches. With refinements I can see search drones being used in ski areas for rescues in conjuction with mobiles. Mobiles should also be used to file routes and ititneraries for universal access in the Cloud which would really help in rescues.
I always thought harnesses were double edged - I always used to snag mine and I was concerned about potential damage if caught in an avalance given I was likley to land on it or rocks impact it. I always thought having them in a secure, padded inside pocket was better.
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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AndAnotherThing.., fair point for the select few but majority of people will have gmail and google+ installed on their android (by default). They will also have to make a google account. These applications register your location as it is, so Google already has a fairly good understanding of:
*What you search
*When/Who you email
*From where you email
*Your online profile (ie the age, gender and personality google thinks you are given on a set of criteria).
So the majority of this information is already well known by Google. By installing Latitude you are, admittedly, giving them more information (the inbetween bits) for your own use.
I would agree with you in that it is bewildering but should you need to stop the service at any point it's done with a click. I use latitude/google now and it's pretty interesting what it gives me. I'm a bit of a stats whore, and it tells me how long I spend at home/work/travelling, has a list of all of my journeys, a mileage calculator, phone buzzes with the traffic news when I usually drive home from work, tells of nearby interests etc. Context-aware computing is pretty cool.
Should get back to work..
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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An interesting paper for you all:
http://plan.geomatics.ucalgary.ca/papers/Schleppe_Lachapelle_ION_GNSS2006_WebVersion.pdf
If used like an EPIRB I can see merit for GPS providing a good approximate location to start a transceiver search to a remote S&R team if you could get a signal out and find some reliable way to trigger it that didn't generate false positives. I could also see GPS being used in a situation like the Tunnel Creek avalanche where the size and terrain mean the rescuers have no clear idea about where the victims are buried. Again the issue is being able to transmit a signal out with the GPS data further than a transceiver can receive already. I'd guess that such an improvement in technology would be better used to improve transceivers and is likely to be far more specialised than anything you'd find in a consumer mobile phone.
I'd also add that the experiments need to be conducted with an object representing a person in various orientations to see how that ends up blocking the signal.
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I think I remember seeing a news article saying Boeing user sacks of potatoes to replicate human bodies when doing signal monitoring on planes.
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You know it makes sense.
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Tell you what Cptsideways, next time you're out on the snow, put your phone in a plastic bag, bury it somewhere and see if your mate can find it. Tip: remember where you put it
Here's what you can do if you integrate a GPS with a beacon:
http://www.pieps.com/en/avalanche-transceivers/vector
But I think it still doesn't transmit your location to your mates.
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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meh, would a GPS signal even work through a few metres of snow? My understanding was that you needed visible contact with the sky for it work accurately.
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Poster: A snowHead
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Timmaah, that's what the paper I linked above tests out in real avi debris fields. The answer is yes they do work under the snow but with some caveats about accuracy and the tests didn't include anything simulating a body which would have implications to the signal strength from the satellites.
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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meh, that paper's very interesting. Conclusion seems to be that it is viable (subject to further testing) and that further software refinement should boost the reliability. Given that the signals were being picked up by satellites I think your distance issue is covered, the problem seems to be the accuracy given the scattering due to the environment (the suggestion being that the correct software tweaks will compensate for this). Also this was all done with a pretty Heath Robinson set up, I think you could get much better results from a tool designed for the purpose. Your Tunnel Creek point is well made and for that alone I think the issue should be followed up (in conjunction with drones). It looks like the US Govt are to require the id function for emergencies in much more 'hostile' environments for satellites so I don't see why it should be too difficult to refine the detection for snow environments.
What I as thinking about was a cradle that would hold your mobile and increase the battery power, amplify your ariel/signal and add a directional indicator function to allow you to track horizontally i.e. take the bits that exist in a normal mobile and enhance them through the existing connectors for power/data.
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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Didn't read all that stuff up there, but I'd think keeping GPS lock and recording position up to the start of a slide is easy. Recording the rough and tumble in a slide might be where it all goes wrong. If that is accurate enough, then after a burial, the GPS signal is not required - it just needs to keep transmitting last known position data.
Be curious to know what frequencies these things work on, and comparing them to falcon trackers. Now those are tiny, and we've found them when buried 1ft deep in farm fields. Shame the tracker part is pretty bulky, but it is directional.
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I note that Garmin has brought its Rino series up to date. They're interesting because they have some special exemption from certain kinds of radio spectrum use that lets them transmit data over a GMRS/FRS radio (US only, of course) connection. They get your position via GPS (and work as a usual handheld mapping GPS device) and transmit it to other nearby users, and by way of a bonus work as reasonably high power walkie-talkies too.
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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| RattytheSnowRat wrote: |
| Given that the signals were being picked up by satellites... |
Eh? The devices were receiving satellite signals, not transmitting anything back.
| RattytheSnowRat wrote: |
| amplify your ariel/signal and add a directional indicator function |
Observations:
- Boosting transmit power is likely to be a no-no under spectrum use laws. Boosting receive sensitivity might well be totally reasonable, but it will be quite difficult to engineer on a modern phone. In the absense of an external antenna port (and do phones have those these days?) you might manage a passive signal concentrator, but it might be a bit bulky. More importantly, it would decrease the signal in some directions, making the user harder to find!
- Peer-to-peer communication between mobiles without the aid of a base station is not within the capabilities of the normal radio networking protocols they use. This would require a major firmware update to facilitate, even assuming that peer-to-peer communication between handsets using their cellular radios isn't in breach of spectrum use laws (which it might well be).
- Re-using the cellular radio system in ways that the phone wasn't designed for is probably impractical for an external device (it will be hidden behind radio firmware which will be hidden behind an interface that on the phone OS kernel can speak to).
- A single antenna radio system wouldn't be much good for direction finding, especially given that mobile aerials will be designed to be more or less isotropic, so in the absense of a data connection you'll not get anything better than an old-school single antenna analogue transceiver in terms of direction finding.
Seems like you'll need two devices on opposing sides of your body and ski within range of a mobile base station that can provide a data connection.
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That Isis thing is about exactly what I had in mind, everyone has a phone these days
Maybe some of you guys with avi gear should try it out & compare
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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That Isis thing is about exactly what I had in mind, everyone has a phone these days
Maybe some of you guys with avi gear should try it out & compare
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Until
a) a phone based alternative technology is given considerable testing to prove it works at least as well as a beacon and once this is done
b) rescue services regularly start using this tech
I will stick with my beacon as that's what the rescue services or your mates will be expecting you to have
I do not want people fannying around wondering if they should use a beacon or a phone to search for me if I get caught in a slide
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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Without having read through the whole of this thread... how about just adding a GPS receiver to the beacon and have that transmit the current GPS coords using the same frequency that it transmits on anyway? Just adding some form of modulation to the transmitted signal would (probably) not mess up other non GPS aware Avi beacons. At least I'm fairly sure one could come up with a scheme to get the data out without messing up non GPS aware searchers. The searching beacon could use the combination of GPS info and received signal from the buried party to zero in more quickly. Transmitter could also be a bit more intelligent and send some indication that it is / is not currently receiving GPS satelites to let the searcher know that the info might be inaccurate. Just a thought. Does such a thing exist already?
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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@altis, yes, if GPS was in continuous operation then it would not be easy to achieve 200 hours. Sounds like you could use Mammut's W-Link to trigger the buried beacon to make it's measurements though*. Again, just a thought.
*I used to work on mobile phone development including GPS where we would get 200 hours of standby with the GPS just doing intermittent measurements. As I recall it only really has to get updated frequently enough so that it doesn't completely lose the satelites, so it can fix again quickly when required. It can be done, but takes some work. The big question is whether the GPS signal is receivable under snow. Probably not, at least not under very much snow.
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You know it makes sense.
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GPS wont work for avalanche beacons for many reasons
- Consumer GPS is only accurate to 1-2m (457kHz beacon is accurate to 10cm)
- GPS doesn't propagate through deep snow reliably
- Large mountains, cliffs or even weather can shield the signal and reduce accuracy up to 10-50m range
- When you turn GPS on it takes several minutes to lock onto the satellites and give the most accurate fix
- Battery life on GPS enabled devices is low
- US military could turn in theory turn the signal off at any time.
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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@Haggis_Trap, the idea is just to get you to the area ( 1 - 2m ) more quickly where the beacon can start to do it's work. Like I said above, you can design the system so it only does intermittent searches and hence can quickly lock while not killing the battery.
I don't worry too much about the US military switching the system off, but if the GPS doesn't propagate through snow then it's a non starter.
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Poster: A snowHead
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^ The flux line followed by a traditional avalanche beacon are a fundamental law of physics / magnetics.
They are not a limitation of the the technology.
Given the numerous limitations above I am struggling to see how GPS could be any faster or more accurate ?
When you turn a GPS on in a new location it can take several minutes to locate the 12 satellites required for 1-2m accuracy....
Even if it did work you would be requiring skiers and rescue teams all over the globe to ditch their existing 457kHz kit for a new standard.
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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and both the transmitting unit and the searching unit have a position error. so 1-2m accuracy for the searcher has to be added to whatever the buried unit accuracy is. so the best case is a circle at least 2x what the searching unit may derive from signal lock. if the buried unit loses lock and transmits last known location, then realistically, you could be talking about "anywhere in the visibly obvious rubble"
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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@Haggis_Trap, the type of scenario we are talking about is where the victim is buried at a significant distance from the searcher. Searcher arrives at the scene, switches his beacon to receive and fairly quickly ( as mentioned above ) gets a message saying the victim is located 200m in that direction... something he does not get with normal avi beacons. The searcher quickly moves within the immediate vicinity of the victim and then uses the normal search methods to locate him exactly. Also it does not mean that traditional beacons don't work, they just don't receive the extra data.
Anyway as I also mentioned above... if GPS doesn't work under snow then it doesn't work. End of.
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@andy,
| Quote: |
| then realistically, you could be talking about "anywhere in the visibly obvious rubble |
That must explain why the e911 system saves so few lives.
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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| Steilhang wrote: |
@Haggis_Trap, the type of scenario we are talking about is where the victim is buried at a significant distance from the searcher. Searcher arrives at the scene, switches his beacon to receive and fairly quickly ( as mentioned above ) gets a message saying the victim is located 200m in that direction... something he does not get with normal avi beacons. The searcher quickly moves within the immediate vicinity of the victim and then uses the normal search methods to locate him exactly. Also it does not mean that traditional beacons don't work, they just don't receive the extra data.
Anyway as I also mentioned above... if GPS doesn't work under snow then it doesn't work. End of. |
457kHZ was selected as the international standard for avalanche beacons specifically because it propagates through snow well.
GPS (1.5MHz) will also go through snow, but there may be accuracy issues if it cant pick up enough satellites - which is not ideal.
If increased search range was required then a simpler solution would be to simply boost the output power of existing 457kHz transmitters.
However this would require bigger batterys (i,e more weight) to meet the transmit / receive times specified in the standards.
GPS might seem like it has a potentially longer range.
However it is not really a fair comparison as the power requirements are way higher.
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@Haggis_Trap, but Steilhang is saying that you can intermittently wake up the GPS receiver so that it can keep track of the satellites. This enables it to make a fix much quicker.
@andy, but the 'differential' GPS error will be much smaller.
@Steilhang, but the GPS information has to get to the searcher's unit somehow. For that to work there must be radio communication anyway so you may as well use a conventional beacon search. If your beacon has an analogue mode you'll be able to detect the victim's beacon long before you can get any digital communications.
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@altis,
| Quote: |
| but the GPS information has to get to the searcher's unit somehow. For that to work there must be radio communication anyway so you may as well use a conventional beacon search. |
Yes, which is why it would be OK with the W-Link system, i.e the GPS data would be sent via W-Link on 869MHz. I assume that 869 MHz has relatively good penetration of snow, as does GSM900 for that matter ( well, water, not sure about snow ).
Anyway, I realise that a bit more research would be needed, but I would not completely discount the idea just yet.
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| Steilhang wrote: |
@altis,
| Quote: |
| but the GPS information has to get to the searcher's unit somehow. For that to work there must be radio communication anyway so you may as well use a conventional beacon search. |
Yes, which is why it would be OK with the W-Link system, i.e the GPS data would be sent via W-Link on 869MHz. I assume that 869 MHz has relatively good penetration of snow, as does GSM900 for that matter ( well, water, not sure about snow ).
Anyway, I realise that a bit more research would be needed, but I would not completely discount the idea just yet. |
Yes that could work. But would have little technical merit over boosting the power of the usual 457khz signal for temporary longer range.
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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FAQ
