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Old 11-09-2007, 08:16 PM   #16
DRTBYK
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Bummer about the Tracking access. I'm not sure what good the SPOT group think that service would be for anyone given the current access restrictions.

The Globalstar sat's are in geosynchronous orbits and if you look on their coverage map you will see that they certainly don't cover the globe. I believe I read somewhere that they are launching new sat's over the next two years that should help reliability and coverage. They are almost giving their phones and service plans away if you buy now with the expectation that it will work better three or four years from now.

As for the ability to send a message, I expect you will need "open sky" to get a good message out since they use the sideband services which I think are rather low power - although somewhat more reliable then their voice services.

I also have a concern about the GPS chip set being used in the SPOT. If it isn't one of the newer more sensitive variety like the SiRF StarIII, I think it will have the same issues with location lock as with the poor message transmission - SPOTty at best ...couldn't resist
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Old 11-10-2007, 02:46 AM   #17
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Quote:
Originally Posted by DRTBYK
...The Globalstar sat's are in geosynchronous orbits and if you look on their coverage map you will see that they certainly don't cover the globe. I believe I read somewhere that they are launching new sat's over the next two years that should help reliability and coverage. They are almost giving their phones and service plans away if you buy now with the expectation that it will work better three or four years from now....
No, their satellites are in low earth orbit (see below from the Globalstar website: http://www.globalstarusa.com/en/content.php?cid=601). They are launching new satellites -- four in May with another four scheduled 'later this year' -- which is a good thing, and their rates are very low at the moment ($50/mo for unlimited talk time in 2007, reduced to $20/mo in 2009). Pretty good deal although they indicate that service will be degraded until they get a new second generation 48-satellite system up beginning in 2009.

Although their coverage map looks like spotbeam coverage by a geosynchronous satellite, I think it their spotty coverage is dependent on the locations of their gateways (gound stations).

Here's the info from Globalstar (feel free not to read ):

"Our Technology
Here is a brief overview of some elements that contribute to the exceptional service and coverage of Globalstar:

Technology / LEO Satellites
A Low Earth Orbit (LEO) is any Earth orbit up to approximately 1,500 kilometers in altitude. Low-Earth-Orbit satellite systems offer significant advantages over Geosynchronous (GEO) systems for the delivery of mobile satellite services (MSSs). These advantages result from an orbit selection that enhances the quality of services to low-power mobile hand-held and vehicle-mounted user equipment. GEO satellite systems, located at an altitude of 35,800 kilometers above the Earth, are best suited for their missions of high-speed data, television transmission, and other wideband applications.

Mobile users, however, need systems that are specifically tailored to their needs. The true mobile user requires hand-held and vehicle-mounted telephone devices with omnidirectional antennas that are easily portable and can provide instant access to a global communication system. Furthermore, telephone users desire and require "telephone quality" transmissions. These users do not want long propagation delays inherent in GEO systems that produce the echo effect and also use bulky, expensive, directional antennas which must point or must be pointed at a satellite.

Also, technical limitations of current GEO satellite systems severely limit the capacity of such systems to service mobile users. The scarce spectrum available for MSSs communications requires deployment of systems that will provide services to the users in a manner that maximizes the use of spectrum while encouraging a multiplicity of systems to share the spectrum. GEO systems, as presently configured with frequency division multiple access-frequency modulation (FDMA-FM), require inefficient band segmentation to share the spectrum.

Compared with a Geostationary system, Globalstar will provide capacity even when a satellite fails. A GEO system, by contrast, would suffer an entire regional system outage if an operational satellite were to fail. Also, current and planned GEO systems cannot service the personal communications market due to the expense of supplying adequate satellite power and practical deployable antenna sizes...."
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Old 11-10-2007, 08:13 AM   #18
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Quote:
Originally Posted by DRTBYK
Bummer about the Tracking access. I'm not sure what good the SPOT group think that service would be for anyone given the current access restrictions.

The Globalstar sat's are in geosynchronous orbits and if you look on their coverage map you will see that they certainly don't cover the globe. I believe I read somewhere that they are launching new sat's over the next two years that should help reliability and coverage. They are almost giving their phones and service plans away if you buy now with the expectation that it will work better three or four years from now.

As for the ability to send a message, I expect you will need "open sky" to get a good message out since they use the sideband services which I think are rather low power - although somewhat more reliable then their voice services.

I also have a concern about the GPS chip set being used in the SPOT. If it isn't one of the newer more sensitive variety like the SiRF StarIII, I think it will have the same issues with location lock as with the poor message transmission - SPOTty at best ...couldn't resist
Opening the web access to SPOTcasting (tracking) is something they are working to change very soon. Remember, that Check Ins and Helps are sent with links to Google Maps now.

Regarding getting messages out - I am purposefully trying to see the device limitations. I have good luck with SPOTcasting points being transmitted when I'm not in the forest or amongst other obstacles that greatly reduce my view to the horizon. Leaving a trail of SPOTcasts would be very helpful in a rescue, even if the actual location of an incident challenged getting your distress message out. Your friends or family back at home would at least have a "trail" of points to use if they decided time had gone by and you needed help. To me, that's probably a good strategy for using the thing in challenging areas when you are by yourself. When you're with another, I think it's pretty likely the uninjured person could move to more open area quickly and get the distress signal out quickly.

GPS signal - the LEDs flash out of unison when the GPS is not getting lock. I have rarely seen this occur. I'd have to say that GPS lock is less of an issue than getting messages out - at least from what I am seeing so far.

TomW - the SPOT rep tells me that the view to the horizon should not be biased towards the southern unless I am at more northern latitudes - I am at Lake Tahoe now. Nevertheless, so far, it sure seems south is more important than the other cardinal directions.
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Old 11-10-2007, 10:51 AM   #19
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Thanks for the correction TomW. Had I thought about it for more than five seconds I would have known that ....
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Old 11-12-2007, 08:45 AM   #20
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I just got one last Thursday as a gift from my wife. For what I do (mainly black top/all over the place riding) this should prove to be a very good solution for checking in at all hours of the day and night without the need for a cell signal, plus she can see where the heck I am.

No test yet, but I'll be playing with it soon. Should be "interesting" to say the least.
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Old 11-12-2007, 10:26 AM   #21
offroute
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Quote:
Originally Posted by GoFar
I just got one last Thursday as a gift from my wife. For what I do (mainly black top/all over the place riding) this should prove to be a very good solution for checking in at all hours of the day and night without the need for a cell signal, plus she can see where the heck I am.

No test yet, but I'll be playing with it soon. Should be "interesting" to say the least.
The perfect use. I don't think you'll see any significant issues with the use you're describing. All my testing on the highway has been good regarding getting my Tracking locations and Check Ins out etc. A great tool to have along on any ride.
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Old 11-12-2007, 03:15 PM   #22
TomW
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Quote:
Originally Posted by offroute
...TomW - the SPOT rep tells me that the view to the horizon should not be biased towards the southern unless I am at more northern latitudes - I am at Lake Tahoe now. Nevertheless, so far, it sure seems south is more important than the other cardinal directions.
Yep, based on what I learned he's right about that, and so are you. I learned from my bro that their satellites are not in true polar orbits (where the satellites wouldn't favor a specific location on the earth). They're in orbits inclined at 52 degrees to the equator, meaning they won't go north of 52 degrees north latitude (or 52 degrees south latitude). Also meaning that at any given time, for those of us in the northern mid-latitudes, more satellites are likely to be south of us than north of us. Some may be overhead or north of us (as long as we're south of N52 deg), but it's slightly more likely that they'll be to the south. I don't know how significant the theoretical latitude factor is, but your informal test to date seems to bear out the generalization.

GlobalStar is having some tech issues with their satellites and from what I gather, they're pushing data applications over voice until they get their second generation birds up starting in 2009.

Interesting factoid my brother picked up: the competing sat phone system (Iridium) was planned for a constellation of 66 satellites and 11 orbiting spares for a total of 77 in polar orbits. The atomic number of iridium is 77.

I think GlobalStar looked at population distribution and decided that most people lived between N52 and S52, so a smaller number of satellites (40) could satisfactorily cover that area from inclined orbits. Clever.

Cheers.
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Old 11-12-2007, 04:23 PM   #23
offroute
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Quote:
Originally Posted by TomW
Yep, based on what I learned he's right about that, and so are you. I learned from my bro that their satellites are not in true polar orbits (where the satellites wouldn't favor a specific location on the earth). They're in orbits inclined at 52 degrees to the equator, meaning they won't go north of 52 degrees north latitude (or 52 degrees south latitude). Also meaning that at any given time, for those of us in the northern mid-latitudes, more satellites are likely to be south of us than north of us. Some may be overhead or north of us (as long as we're south of N52 deg), but it's slightly more likely that they'll be to the south. I don't know how significant the theoretical latitude factor is, but your informal test to date seems to bear out the generalization.

GlobalStar is having some tech issues with their satellites and from what I gather, they're pushing data applications over voice until they get their second generation birds up starting in 2009.

Interesting factoid my brother picked up: the competing sat phone system (Iridium) was planned for a constellation of 66 satellites and 11 orbiting spares for a total of 77 in polar orbits. The atomic number of iridium is 77.

I think GlobalStar looked at population distribution and decided that most people lived between N52 and S52, so a smaller number of satellites (40) could satisfactorily cover that area from inclined orbits. Clever.

Cheers.
Interesting info TowW. Thanks!

I've used GlobalStar sat phones in central Idaho a few different times. I was constantly having to climb up different sides of the Middle Fork Salmon canyon walls to be able to use the thing. It was pretty frustrating. My experience with the SPOT device here in the Tahoe area is certainly much better than that.
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Old 11-15-2007, 09:51 PM   #24
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how are we doing here? any updates?
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Old 11-16-2007, 12:00 PM   #25
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markgsnwhow are we doing here? any updates?


While sitting here with a broken leg, I am vicarously watching my son, Offroute, having fun. I tracked him and his friends from their campsite under a tree west of Lone Pine Wednesday night, and yesterday in almost realtime do Saline Valley, Lippincott Canyon, Racetrack, Teakettle Junction, Hunter Mountain and Cerro Gordo in Google Earth Hybrid. Today, I am tracking them from their campsite at Furnace Creek, and they are presently up in Echo Canyon. This tracking feature is amazing. wv
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Old 11-16-2007, 06:15 PM   #26
KenR
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I went out today for a quick 175 mile loop. Pressed the OK check-in button five times throughout the ride and everyone on my list got text messages and emails within a few minutes. I haven't tried the tracking feature yet - maybe tomorrow - but I'm very impressed.
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Old 11-17-2007, 07:59 AM   #27
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How do you guys have the Spot unit mounted on your bike?

Cheers.
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Old 11-17-2007, 08:38 AM   #28
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I just throw mine in the front pocket of my enduro jacket - don't even know it's there.

One thing that did happen yesterday has me a bit perplexed.

I have a Garmin 276c mounted on the bike. At two different times yesterday the GPS seemed to lose it's position, presumably after I hit the OK button of the Spot. The speed was still reading correctly in the display, but the map froze up and showed me about 300 miles from my correct position. Both times I simply rebooted the GPS and it went back to working correctly.

So I'm wondering if there's a conflict between the two devices or if this was just a coincidence. I've never had that happen with my 276 before yesterday. The Spot recorded all of my check in's correctly. This obviously calls for more testing before winter arrives here on Monday - at least that's what I'm telling my SO.

Anyone else have this happen?
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Old 11-17-2007, 09:45 AM   #29
TomW
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Quote:
Originally Posted by KenR
...One thing that did happen yesterday has me a bit perplexed.

I have a Garmin 276c mounted on the bike. At two different times yesterday the GPS seemed to lose it's position, presumably after I hit the OK button of the Spot. The speed was still reading correctly in the display, but the map froze up and showed me about 300 miles from my correct position. Both times I simply rebooted the GPS and it went back to working correctly.

So I'm wondering if there's a conflict between the two devices or if this was just a coincidence. I've never had that happen with my 276 before yesterday....
I'm not surprised. The GPS satellites transmit in a band at 1,559 - 1,610 mHz and GPS receivers need to be quite sensitive as they usually don't have much antenna to work with. The GlobalStar/Spot systems' handset transmits in the band 1,610 - 1,625 mHz with significant power necessary to access a satellite in an orbit 1,000 miles up (again with little help from the antenna). This probably overloads the GPS' receiver. I doubt that these civilian units are designed to reject relatively huge signals on adjacent frequencies.

A cure? Dunno -- anything you can do to separate the GPS and Spot antennas as much as posible will help. Let us know if you have any luck with this.

Cheers.
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Old 11-17-2007, 11:30 AM   #30
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I would think (?) that the hardware designers accounted for the proximity of transceivers and provided the appropriate filtering. Otherwise it wouldn't work at all. But they probably have a very small antenna for the GPS. And, I suspicion that they did not use the latest high-sensitivity GPS receivers (e.g, SiRF StarIII) in order to meet the SPOT h/w price point of $149.
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