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Kevin Burton
(burtonator) - F - M

Locale: norcal
Personal Locator Beacons... on 07/01/2013 23:38:37 MDT Print View

Interesting review that was updated on March 13 2013:

http://www.outdoorgearlab.com/Emergency-Electronics-Reviews

The market is definitely interesting here.

It seems to fall into two camps. 1 are devices that allow 2 way communication via a smartphone but they have mediocre SOS performance. The other is ones with VERY good SOS performance but no communication capability.

I think I"m leaning to the DeLorme InReach Satellite Messenger ... but of course it's 232g vs Spot Connect at 139g ... of course I think in this case weight isn't the only issue.

The Spot Connect apparently has bluetooth pairing issues.

Of course REI sells the Spot Connect so I should be able to buy it and return it if it doesn't work.

I think if I were to go on a larger group expedition that I would want to have a real SOS device.

Trace Richardson
(tracedef) - MLife

Locale: Southern California
PLB ... 406 on 07/02/2013 00:18:27 MDT Print View

I like the ACR ResQlink 406 because it can be used for sailing as well as they make a ACR ResQlink+ 406 (notice the plus sign) that is a buoyant version of the 406, so perfect for a sailing ditch bag ... it sends out signal at 406 mhz for initial position to satellite and also sends out 121.5 homing signal for searchers that are closing in on your location to follow ....

5 watts, batteries good for 5 years, under $300, no annual subscription, 130 grams, has built in strobe light .... pretty solid piece of equipment! Finally, if "If actually getting rescued is your top priority" as Outdoor Gear Lab mentions .... they're giving it their vote as well. :)

Mike W
(skopeo) - F - M

Locale: British Columbia
Personal Locator Beacons... on 07/02/2013 01:23:07 MDT Print View

I think it's a bit more grey than that. While I will not argue that a PLB has the best chance at bringing a rescue team, you have to be physically capable of triggering the beacon. The tracking devices on the other hand will mark your last known location if you fail to return from a trip (if you have the tracking turned on). I think this feature alone can be considered a significant rescue feature and not just a "chat" device. I'm not aware of a PLB that provides any kind of tracking.

PLB's and satellite communicators do serve two distinct purposes though, and the subscription fee that you pay for the communication device shouldn't be seen as a "charge for rescue" fee. You don't get text messaging on your phone without a service plan, so you should expect to pay for one way or two way satellite text messaging.

Here's the way I see it. If you are only worried about being rescued, buy a PLB.

If you want to let your family or friends know where you are with either tracking or messaging, get a communicator and consider the SOS feature a bonus (a bit of added security for you and your family).

I've owned a Spot Connect, an inReach and an inReach SE. (Bluetooth pairing on the Spot was never an issue for me but the service let me down on a couple of occasions). The inReach worked well but I wanted to leave the smart phone out of the equation, so now I'm testing my inReach SE.

So when would I rely on these communicator devices? I use the tracking all the time and sometimes send messages for fun. I've used mine twice for important but not critical issues... once to ask for a ride when I left the trail earlier than expected (and in a different location than expected). The second time was to notify a friend where we had set up camp (we weren't sure where we would stop and set up camp as there were multiple choices). He was going to join us but was leaving a day later.

Kevin Burton
(burtonator) - F - M

Locale: norcal
Re: Personal Locator Beacons... on 07/02/2013 13:18:22 MDT Print View

I totally agree... the tracking beacons are the most important I think. If something happens and you can't hit the rescue button on your beacon it doesn't matter. You could get hit by a rock or simply fall down a ravine and unable to get to your rescue beacon.

Having it track you every 30 minutes means rescue can find you within a given region and usually that's 1-2 miles if you're sending off a ping every 30 minutes.

I've needed to send messages multiple times. One I forgot to feed the cats for example and I had to hurry back sooner than I would have hoped.

Further, if there is a work emergency they can text me and I can leave earlier.

Mike W
(skopeo) - F - M

Locale: British Columbia
Personal Locator Beacons... on 07/02/2013 14:28:41 MDT Print View

>> Further, if there is a work emergency they can text me and I can leave earlier <<

That's the one I'd definitely ignore. :)

I like the idea that I can ask somebody for a weather report. Many of the areas I hike in the weather can change daily (sometimes hourly but you can't plan around that one). Helps me decide whether to increase mileage or not.

Greg Mihalik
(greg23) - M

Locale: Colorado
Re: Re: Personal Locator Beacons... on 07/02/2013 15:39:58 MDT Print View

"Having it track you every 30 minutes means rescue can find you within a given region and usually that's 1-2 miles if you're sending off a ping every 30 minutes."

But how soon will S&R come looking? Two days after the end of your trip?

Or are you making someone at home responsible for following your progress and then calling for help if you don't move for 48 hours?

Eric Blumensaadt
(Danepacker) - MLife

Locale: Mojave Desert
"9-1-1", tracking and CYA on 07/02/2013 17:23:39 MDT Print View

I like the regular SPOT beacon because I like its tracking ability.

Of course that presumes you have someone that actually CHECKS their computer to see what your progress has been and actually gives a rat's a$$ about your welfare.
(NOTE: Not all spouses and girlfriends/boyfriends fall into this category gentle hikers.;o)

Once again -battery powered devices:

SPOT beacon
headlamp
Topo GPS
digital camera
mini i-pod (??)


There are getting to be way too many backpacking "essentials" that require extra batteries be carried along.

How about a REALLY smart phone that incorporates all of these, is waterproof to 30 ft. and shockproof if dropped on concrete from 10 ft? "Eh?"


Speaking of "eh?".
Canadian alphabet: A, eh? B, eh? C, eh?...

How Canada got its name:

In 1730 three drunken Voyageurs sitting around a campfire decided to name the country.
They decided each would pick a letter to use in the name.

Voyageur #1-> 'C', eh?"
Voyageur #2-> 'N', eh?"
Voyageur #3-> 'D', eh?"

Smart Indian in background-> "OK. Got it! CANADA"

Edited by Danepacker on 07/02/2013 17:25:37 MDT.

Stephen M
(stephenm) - MLife

Locale: A very flat place (Grrrrrrrr)
Re: Personal Locator Beacons... on 07/02/2013 17:46:53 MDT Print View

One thing to watch with the spot is you do not not know if your text sent or if your tracking is working, is at it one way
Only, the In reach works both ways.

When I am in the middle of nowhere with buddies we carry a Plb and a sat phone,.

Paul Huber
(LS2379) - F

Locale: Central Virginia
Spot doesn't always work on 07/02/2013 17:55:30 MDT Print View

I have read quite a few times, especially with climbers, where the spot does not work when needed. I would rather have something that works when I need it, than something I can chat up my trip with.

Zorg Zumo
(BurnNotice) - F
Re: Personal Locator Beacons... on 07/02/2013 19:39:48 MDT Print View

A nice read - thanks for posting the link to the article. Just one problem though - the SOS summary. Totally unsupported assertion that the ResQLink is better than SPOT 2. I would like to see the data on that.

There are reasons why ResQLink COULD be better, but I haven't seen any data showing that it is. An assertion without data is simply Male Bovine Excrement nicely written.

Billy Ray
(rosyfinch) - M

Locale: the mountains
nothing is perfect... on 07/02/2013 20:28:58 MDT Print View

there are problems with tracking too...

for instance... I read a story where a guy had his spot tracking... decided to take a lay-over day in a great place... his wife didn't see the spot tracking moving... she called for rescue !!!

Besides the inconvenience... and embarrassment.... that can cost thousands if they choose to bill you...

I for one, wouldn't want to have someone looking over my shoulder... or fear for taking an unscheduled lay-over that the helicopters will be on their way... crazy...

plus... being that this IS 'backpacking light'... remember... if you're on a long trip and want to do tracking that will take extra batteries... and ounces...

what happens if you run out of batteries?.... tracking stops... and then the helicopter come... again???

bill d

Rob E
(eatSleepFish)

Locale: Canada
Nothing always works: some comments in defence of the SPOT on 07/02/2013 21:06:09 MDT Print View

I'll just chime in to say that I have a Spot 2 messenger, and I'm very pleased with it. I have used it for two years now, and have never not had it send a message... not that it has needed to, as I've never had to deploy it in a life-or-death situation. Given the state of the market right now as of July 2013, I would probably buy exactly the same unit again, though, I'd give serious thought to the Delorme InReach SE.

Some background: I'm no professional reviewer, but I have used both Iridium and Globalstar sat phones for work at remote camps, and at work we have both spot messengers, sat phones, and delorme inReach (the clunky version that pairs only with the Delorme EarthMate GPS... we don't like it).

I think that there is a lot of negative feedback about the spot messenger, some of it warranted, some of it not. The major problems with the spot messenger, as I see them, in order of importance, are:

1.) Unrealistic user expectations. If you read forums and trip reports where people had to use spot, you will find that usually the device and system operated just fine. Help arrived within a few hours and no one died. The user would describe a stressful period where they didn't know if help was coming or not. Well, of course not! You have a one-way communications device. In particular I'm thinking of a recent discussion on BPL concerning the avriders.com motorcycling forum thread that came off really negative of spot, but really, the device worked fine, help arrived. Someone had to endure a broken leg for a few hours.

People think that they hit this little SOS button and a team of navy seals and a fleet of chinooks is going to fly in within seconds. This is not the case. Spot is very clear that they are only going to contact the local SAR authorities and leave it up to them. Spot and globalstar have absolutely nothing with putting boots on the ground and getting actual help to you. They sit in an office with a phone and make a few calls, first of which, will be to your emergency contact numbers. AFAIK (and welcome feedback on this), chances are in most instances, the same group that would be contacted by your PRB would be contacted by Spot/GEOS rescue.

When I use my SPOT on serious trips I have made sure that my two primary safety contacts know of my plans, which SAR/agencies/people to call, and try to give some information to my safety contacts of SAR resources available (which really is only a quick google search away).

2.) Difficult web based user interface. Now, I'm going to step out on a limb, and say that I think that many of the forum/web/blogger reports of Spot not working are due entirely to user error when entering the contact information on the spot website. I'm sure I'll take some flack for suggesting this, but my experience using their website over the past few years suggests that many of the reports I read on the web about spot not working are due entirely to web interface. There are a few big problems with the web interface:

- you need to click a separate "save" button, which is often located below your visible screen, when adding/editing a new number in order for it to actually be saved. I think people are used to the iphone/ipad/web 2.0 world where you type things in and it just works, but the spot website is definitely clunky. Many times I have entered 10 email addresses to have them lost because I didn't click this save button, well outside of my currently visible screen.

- difficult to change profile. This happened to me just two days ago. You'd think that after using Spot for 2 years regularly that I'd be an old hat, but I created a new profile with contacts for a packraft trip, added all the necessary contacts, but somehow, the profile never got activated.

- in short, it is extremely easy to enter information to the spot website, but to have it get lost, not saved, or not active.

I seriously think that Spot should spend the money to have a good modern web programmer have a go at their interface, and I'm sure it would save them a lot of bad press that people are attributing to the messenger/gps/satellite constellation itself not working.

3.) Not allowing GPS information to download and obtain a fix. If you have moved location more than more than ~100km, or you change your devices battery, or you have gone a few weeks without using your Spot, it's going to take a long time to get a GPS position. This is just a fact of using GPS.

I've been on web forums where people think a GPS cycling computer is defective because it can't sit in the basement for a few months and then instantly obtain position and velocity after being turned on while moving.

When I get to a new location for a trip, I let the Spot download information for 20-30 minutes, and send a test message to make sure that both the spot is working, and that my contact list is on the website is working correctly. Then when I send check in/ok messages, I try to do it in situations such as eating lunch, and I let it sit there and transmit for as long as I am sitting there eating/snaking/setting up camp.

My belief is that in many instances where spot is claimed to not work, it is being turned on for only a few minutes to send a message, while having not been turned on in weeks, or with new batteries.

Those are the big 3 observations I have about user reports of spot messengers not working on the web. Now, I am sure that many of these instances are of the spot device actually not working, which is alarming, which brings up another point:

The spot is the iphone of satellite messenger devices, there are more of them out there than any other device, so, they send a lot more messages, and a lot more cases of it being used. If your only perception of an iphone was a google search for "iphone doesn't work", or by reading http://discussions.apple.com, you'll find millions of hits and stories that the iphone doesn't work, and be forced to conclude that the iphone is an inferior product that simply doesn't work. In truth, it works fine 99.99% of the time.

Continuing on, I think that there are some serious limitations to the SPOT messenger.

4.) Globalstar satellite constellations. I know that satellites can go out of orbit, so when I send check in/ok messages, I leave it on for as long as possible.

5.) Not actually a SAR organization. GEOS SAR coordination is probably only an unpaid intern with the yellow pages and a rolodex of other SAR organizations. If your local sherrifs office isn't to be trusted to launch a SAR this is not Spots/GEOS fault.

6.) High latitude environments. This is a known limitation of the Globalstar constellation, and an important limitation to keep in mind. I've had spot work fine at a lattitude of 55degrees North (which is not very far north), and had it work fine deep in a valley. If I were going to northern Alaska would I trust a spot? Probably not, it not working in northern Alaska wouldn't stop me from recommending it to a user in lower latitudes. I think that many knowledgable web/bloggers/forum users from Alaska and the north dissuade others from using the Spot simply because it might not work in that particular geographic locale.


What I like about the SPOT:

I like the size, weight, and battery life. The Spot 2 is tiny, and it lasts a long time on a set of 2 AAA batteries. I know people will complain that it doesn't last to the end of the universe, or that it doesn't use CR2032, or use AA, or D cells, or have a usb charger, whatever, for me, the spots battery life is excellent.

I like that there is no smart phone, GPS device, pairing, or other issues. It is a standalone, one-way, easy to use communications device.

I like the tracking feature. I leave it on, and try to make an effort to have it facing "skywards" in my pack or packraft. Sure, track messages might get lost, but if I do go missing, narrowing the field down from a few hundred square kilometers, to a few square kilometers is going to save a tremendous amount of SAR time, even if it is to only find my bloated corpse.

I like that it is only one way communication. I know that in an actual emergency situation that being able to communicate would be a big help... describing the nature of the emergency, the location, all the details, could save a life. However, I don't think that what I do is particularly dangerous. If I did consider it particularly dangerous or exposed, I would buy or rent a different communication device.

I feel that the spot is a comforting piece-of-mind for those at home, and a possibly life saving piece of communications equipment, but it also leaves me at arms length. I'm not reachable, and I can't sit in my tent and SMS friends about the hockey score. I know the purists will say, "Well, just don't use your sat messenger to text". Well sure, I won't (or i'll try). But, I don't think that many will heed that advice. I actually like the one-way nature of SPOT: I'm alone in the wilderness, but can let my loved ones know I'm safe, and can slightly increase my chances of survival in an unplanned life-threatening emergency.

I know this is a long, poorly written, and lackluster essay on the merits and limitations of SPOT. I just feel that the SPOT is always being dragged through the mud. Nothing always works, and nothing is 100% safe 100% of the time. If another device becomes popular, which it looks like the Delorme InReach SE will, we'll see forum posts about it not working as well.

PLBs, Delorme, Satellite phones, there are a lot of of devices out there now, each with their own strengths and weaknesses. Rest assured that if a device had negative weight, near eternal battery life, and worked 100.0000% of the time that this and other webforums would find flaws, and still manage to have threads about it that would devolve into personal attacks.

I'm going to continue using my SPOT 2 messenger, and continue recommending it to friends. Though, I can be a little bit cavalier in this regard: I once breathed campfire smoke, so according to BPL I'm not long for this world anyway.

Edited by eatSleepFish on 07/02/2013 22:12:32 MDT.

Zorg Zumo
(BurnNotice) - F
Re: Nothing always works: some comments in the defence of the SPOT on 07/02/2013 21:50:18 MDT Print View

Nice writeup! I've been using SPOT since 2008 and it just works. It is an excellent IQ test and some users fail.

BTW, GEOS is a pretty advanced coordination center that is contracted to others as well. Local SAR really varies a lot with each county in the US. If you are by the coast, the Coast Guard will likely be the first responder. If you are in the middle of Idaho, no helicopter is going to fly out, so be prepared to spend a night or two.

Edited by BurnNotice on 07/02/2013 21:58:22 MDT.

David Thomas
(DavidinKenai) - MLife

Locale: North Woods. Far North.
Re: Nothing always works: some comments in the defence of the SPOT on 07/02/2013 22:12:50 MDT Print View

I owned and used a SPOT for 3 years and have gone to the ResQlink.

Rob, your points all have some validity, but my experience differs in several areas. To keep your numbering scheme:

1) unrealistic expectations - I wasn't expecting the Cavalry and I knew that performance would be limited in valleys and high latitudes. The extent of those limitations is much of the reason for my switch. AFASIK, SPOT's ability to ping its satellite system is the same for a message as for an SOS. And those messages are pretty damn SPOTty getting out.

2) Difficult web interface. Not for me. I'm sure I did it correctly, because at times, the receipents would get the messages.

3) Not giving it enough time. I don't count as a fail the times I'd hit "OK" and keep moving or was in forest cover, or would only wait 2 minutes. I'm counting as fails when I used a location with the most open sky I had available, on top of a rock, unmoving for 10-20 minutes at time until it timed out and stopped transmitting. And then, often, repeating the cycle.

5) dodgy employees: Not an issue with automated messages being passed along, although I suppose there may be an additional link in the chain for an actual SOS that could fail.

6) high latitude. I live in the largest state in the USA and I'm south of most all of its population. I would get some success and some failures here at 60N. Friends who took it to 65N had perfect sky conditions (no hills or mountains or trees) and also had mixed results. People can differ in their idea of "high latitude". But I had more failures in valleys at 35N which I don't think anyone but Aussies thinks of as very far north.

And then there's the annual fee. Since the message function is so untrustworthy, I didn't use it much because people would worry if they got no "OK" messages. And since the messages were untrustworthy, I didn't trust the SOS function. For SOS only, I went with a non-fee option.

SPOT has had saves in Alaska. As has every system, even the old 121.5 MHz beacons that some friends have activated at times and others have used to search. (It was the loss of our Senator's father, US Rep Begich and Hale Boggs, in 1972, which resulted in ELTs going into planes).

But by communicating with more satellite systems including some in polar orbits, I like how the ACR units increase the chances of being heard. Especially since, if I most need it, I may be least able to get to ideal high ground on a slightly south-facing slope, out of the trees.

Rob E
(eatSleepFish)

Locale: Canada
Re: Re: Nothing always works: some comments in the defence of the SPOT on 07/02/2013 22:27:42 MDT Print View

Dave, was your experience with the original Spot messenger, or the second revision?

One aspect about the PLBs that are often touted, and that I find quite interesting, is the directional radio beacon. Do you think that this works and is a useful feature in practice and has proven to be useful when needed?

David Thomas
(DavidinKenai) - MLife

Locale: North Woods. Far North.
Re: Re: Re: Nothing always works: some comments in the defence of the SPOT on 07/02/2013 23:04:20 MDT Print View

I had what is now an older, bigger unit. Purchased in 2008.

I wish you could ping the PLB system and learn about it, but of course, that isn't allowed. Maybe I'm being unfair to SPOT because I have lots of experience with it not working. But talking to multiple systems seems better and (especially up here) including some with polar orbits seems better.

I was pondering when I might hit the button on my ResQlink when I was on a boat that sunk in Cook Inlet in May. And deploying the antenna is one more step to take (before your hands get too cold).

I know diddly about antenna design, but I note that, generally, bigger antennas let you have greater range (i.e if ACR could do as well with an interior antenna like SPOT has, wouldn't they?). Maybe Bob Gross could weigh in.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: Re: Re: Nothing always works: some comments in the defence of the SPOT on 07/03/2013 00:02:14 MDT Print View

"I know diddly about antenna design, but I note that, generally, bigger antennas let you have greater range (i.e if ACR could do as well with an interior antenna like SPOT has, wouldn't they?). Maybe Bob Gross could weigh in."

Dave, that is not a good assumption.

Most of the time, the _length_ of the antenna is related to the frequency of operation. Sometimes an antenna can be all curled up inside an enclosure, and you can't really tell what you have. In general, the longer the antenna, the lower the frequency of operation.

Some of these modern devices are purely GPS receivers, so they are fixed for the 1.57GHz civilian downlink frequency. They ignore the military frequency.

Some of these are trying to transmit out (or up) a 406MHz signal to a moderately high geosynchronous satellite. That takes a certain amount of power.

Others of these things are trying to transmit to a low earth orbiting satellite. Less distance to cover, so lower transmit power required.

Generally it is the transmit power that gets you the necessary uplink range.

How would you like to deploy a dish antenna, say one meter diameter? That might help in the transmit function, but it would sure be a pig to carry around.

What would be neat is if one of these suckers were dual mode. You could send and receive messages using the sat phone functionality, but then when a real emergency happens, you could press the special button and it goes out on 406 to the high bird.

--B.G.--

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: Re: Re: Re: Nothing always works: some comments in the defence of the SPOT on 07/03/2013 00:20:54 MDT Print View

With regard to user error with a Spot device, I think it really happens.

Last summer, some friends of mine were backpacking high in the Sierra Nevada. One person was getting all of the classic symptoms of HAPE, so an evacuation plan was thought up. First, two strong hikers were sent out together to the nearest trailhead in an attempt to call for help. Cell phones don't have much service that far out in the boonies. Second, some nearby backpackers had a Spot device. After a lot of thought, finally the button was pressed. Everybody kind of sat back and tended to the ill backpacker, maybe waiting for the helicopter to show up. Meanwhile, the nearby backpackers felt like their job was done, so they took off down some trail.

The emergency report came to the nearest County Sheriff's Department. But then, they noticed that the reported coordinates were moving away from the initial contact point (the nearby backpackers were going their way with Spot still transmitting). The Sheriff's dispatcher therefore assumed that it was a false alarm, so they scrubbed the helicopter mission before it took off. Meanwhile, much later, the two hikers got out to a road and called for help. Then the County Sheriff's dispatcher got the second report for the same initial place, so they scrambled the helicopter again. The sick person was evacuated, and all lived happily forever. Actually, the evacuation was a bit of a problem. The helicopter did not have much lift at high elevation, so the pilot had to wait for wind to shift, burn off excess fuel weight, and even then they could only take out the victim with zero of the victim's gear.

My point is that if you get one of these things and try to use it, you want to have a pretty clear understanding of what kinds of things are going to screw it up, either getting a signal transmitted clearly, or getting it interpretted correctly.

--B.G.--

Mike W
(skopeo) - F - M

Locale: British Columbia
Spot issues definitely weren't just user error... on 07/03/2013 01:46:56 MDT Print View

My poor experiences with the Spot Connect was not related to user error although Spot customer service tried to blame me even though I was able to show them exactly where it went wrong (and it certainly did go wrong on a couple of occasions).

In the end, I received this in an email from Spot support

"We apologize for this error. This occurs when you make changes via the SPOT web account or on your Connect app and do not Sync the app. We are aware of the error and have our programmers looking into the issue."

I found this pretty insulting really, because not only did they try to blame me for not syncing the device (which I did and it scrambled the contacts), they immediately followed by saying it was a known error and their programmers were working on it!! If it was my fault for not syncing the app, then what were the programmers working on?

I was actually able to show Spot Customer Support that my sent logs clearly showed the contact that my message was sent to was correct on the iPhone App, but when the message passed through Spot head quarters, it changed the contact to somebody else. I would hope they've fixed this issue by now but for me it was the last straw and I bought an inReach and stopped using the Spot.

Previously, I had experienced very poor results with the tracking and did side by side comparisons with my inReach and my Spot Connect and the inReach provided a perfect track every time (I frequently do a local 10K loop under moderate tree cover, so it's easy to compare track results). I didn't ever get a complete track from the Spot Connect after many tries and attempts to position the device in an optimum location. I even carried it in my hand (holding it out in front of me) and I could watch it lose it's connection to the satellites (light turned red) under not very dense woods.

I will say that I suspect the Spot Connect is probably worse than the standard Spot device (the stand-alone device). It would be interesting to compare the tracks from both these devices and see if the regular Spot out-performs the Spot Connect.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Spot issues definitely weren't just user error... on 07/03/2013 03:51:42 MDT Print View

"I even carried it in my hand (holding it out in front of me) and I could watch it lose it's connection to the satellites (light turned red) under not very dense woods."

Mike, what does this red indicator mean, exactly?

This device is a one-way transmitter, up to the bird. How in the hell is it supposed to know whether its transmit signal is getting to the bird? There is no downlink.

Now, I can understand that if it thinks it is having an internal failure, battery failure, or something critical like that, it might light up a red indicator.

Suppose that you move underneath a dense tree. This device should have no way of knowing that its transmit signal is mostly blocked.

The only thing that I can think of is that it uses the GPS downlink as a proxy. If the GPS downlink is good, then it _assumes_ that an uplink signal will be good. It doesn't know, but it assumes. Since the different satellites are in different places in the sky, I don't know how good of an assumption this is.

--B.G.--

Edited by --B.G.-- on 07/03/2013 03:56:15 MDT.