Spot-2

stolenheron

Explorer
I just picked up and activated a brand new SPOT-2. bass pro shops has a $50 rebate offer going on right now.

Who has the units? reviews? Battery life with the 3 lithium batteries?

I set all my messages, set my contacts (cell phone numbers and emails). I got some questions. How long does it generally take for a message to be received by one of those contacts (both text and emails)?

I spend alot of time in areas with no cell reception and end up in some fairly dangerous situations at times (usually involving venomous snakes). Most of my time is spent in the swamps of SW florida or the forests of the SE US (Central, AL mostly).
 

NuggetHoarder

Adventurer
I can give you the information I've gathered so far, but I cannot verify it. Hopefully this will move the discussion along and others can confirm or correct what I'm about to write...

The SPOT device uses the Globalstar satellite constellation. Globalstar has had a lot of problems over the past several years and their voice coverage kept dropping to a point where if you wanted to make a call, you usually had to wait up to an hour for a satellite to come into view, and then you'd only get a few minutes of call time before the satellite passed out of view. They recently successfully launched 6 new satellites and those should be operational by summer 2011 and more launches are planned.

As of March 2011, for most of North America it appears that you will typically have to wait about 20 to 30 minutes for a satellite to come into view, and then you'll have about 13 minutes or less to make your voice call. You can see how this works by going to http://calltimes.globalstar.com/ Globalstar has had so many voice customers quit the service that they are currently offering a $20 a month unlimited voice plan with one year commitment that is good through the end of March 2011, in order to keep customers. Not a bad deal at all compared to Iridium and especially if you don't need to make instant calls and can wait 20 to 30 minutes for a signal. As a comparison, if you turn on your Iridium phone, which uses Iridium's constellation, you will almost instantly acquire a signal and be able to make long calls immediately. This helps explain why Iridium is twice the cost of Globalstar for the phone, and 100 times or more expensive for the usage minutes. So Iridium is expensive, but for a good reason.

Here's where it gets tricky - Globalstar has both duplex and simplex transmission. Globalstar sat phones are duplex (two way) and that is what I described in the paragraph above. The SPOT device uses simplex transmission (one way) so theoretically it should have better coverage than voice. It's the same satellite, but the SPOT only uses the simplex side of the satellite.

Simple deduction, and using Globalstar's own calltimes tool, would imply that the worst case scenario for a SPOT transmission would be that it would take a maximum of 20 to 30 minutes to acquire a signal and then transmit a message. That's as of March 2011 and should, according to Globalstar, improve by the summer of 2011 and get even better with the next satellite launch.

Globalstar publishes maps of both simplex and duplex coverage and the simplex coverage is much more dense, especially in outlying areas like Alaska and Canada. This would imply that it is easier to acquire a satellite for simplex than it is for duplex. http://www.globalstar.com/en/index.php?cid=101&sidenav=85

What I described above - the 20 to 30 minute wait times to acquire a signal, matches some of the implied performance that is written into the SPOT user manual, however I haven't found any hard data from SPOT. The most I've found is a press release saying "There is a proven 99.4% reliability with the SPOT system. They process over 6 million messages a month or approximately 2.3 messages per second." This same press release says the AA lithium batteries have a 12 month standby capability. The press release is a couple years old so the 99.4% number may be inaccurate and is most likely low since the successful launch of six satellites in October of 2010.

Again, most of what I've written above is anecdotal and hopefully we'll get some experts on here to confirm or refute all of this.
 

Paladin

Banned
I can't confirm, but I believe the SPOT sends the signals about every 15 minutes. You can see by watching when the sending light turns off. If I understand correctly, that light doesn't go out until the unit recieves confirmation that the message is sent. I don't know exactly how long the delay is between the satelite getting the message, and your recipient recieving a text.

Battery life depends on how you use it. I can only say that I have not found the published figures to be inaccurate. I'm still on my first set of batteries, I've got several days of "tracking" use on them. I carry an extra set with me. I tried really hard to find an alternative to using the expensive lithium cells, and have found nothing. Let me know if you do. I did try 1.5V alkalines, and they did not work. Regardless, the battery life is really quite long, I'm not too concerned about the price anymore.
 

teotwaki

Excelsior!
In the Western U.S. when I am in areas with cell coverage I get the SPOT text message on my phone in a couple of minutes after hitting the sned button. Naturally that is the very best scenario but I've not had to wait too much longer most times. You have to remember that if the SPOT device cannot get a good GPS signal it will not transmit until it does. Because of this and antenna limitations the SPOT device will transmit 3 times in a 20 minute period. Because SPOT is a ONE-WAY device, it has no knowledge of message receipt and it does not even have a receiver to get a confrimation message. The only receiver in a SPOT device is the GPS chip set.

The performance difference between the phones and data devices like SPOT was because older satellites had bad transponders for the phones but the transponder used by SPOT was at full performance levels

That is old news though as new satellites have been going into orbit on schedule which will improve the issues with the Satphones. The old satellites have worked fine for SPOT without delaying messages.

http://www.spacetoday.net/Summary/5081

Soyuz launches Globalstar satellitesPosted: Wed, Oct 20, 2010, 7:17 AM ET (1117 GMT)
A Soyuz rocket successfully launched the first of a new generation of communications satellites for Globalstar late Tuesday. The Soyuz 2-1A lifted off from the Baikonur Cosmodrome in Kazakhstan at 1:10 pm EDT (1710 GMT, 11:10 pm local time) Tuesday, carrying six Globalstar-2 satellites; the Fregat upper stage released the satellites into low Earth orbit an hour and 40 minutes later. The satellites, weighing 650 kilograms each, were built by Thales Alenia Space for US-based mobile satellite communications company Globalstar to replace its existing fleet of satellites. Those original satellites, launched over a decade ago, have suffered transponder problems that prevent them from relaying phone signals. Three more Soyuz launches, each also carrying six new Globalstar satellites, are planned for the first half of 2011.


other article
http://www.satellitetoday.com/twitter/Globalstar-Takes-Next-Steps-in-Repairing-Voice-Services_35826.html
 

Paladin

Banned
I thought the Spot could get a message back from the satellite that the satellite had in fact recieved the message from the Spot?

So, you press send, Spot waits for the GPS signal (which in my experience, reception with Spot2 is very good), Spot gets the GPS coordinates, and start sending the message to the satellite, when the satellite gets the message, it tells the Spot device the message was recieved, and the Spot device then stops transmitting.

The Spot device seems to know when the message satellites are in range, because most of the time the transmitting light turns off after a few minutes, sometimes it stays on for a long time. Not the red GPS light, but the message sending light. So sometimes it has a GPS signal, but it knows it hasn't transmitted the message successfully.
 

teotwaki

Excelsior!
I thought the Spot could get a message back from the satellite that the satellite had in fact recieved the message from the Spot?

So, you press send, Spot waits for the GPS signal (which in my experience, reception with Spot2 is very good), Spot gets the GPS coordinates, and start sending the message to the satellite, when the satellite gets the message, it tells the Spot device the message was recieved, and the Spot device then stops transmitting.

The Spot device seems to know when the message satellites are in range, because most of the time the transmitting light turns off after a few minutes, sometimes it stays on for a long time. Not the red GPS light, but the message sending light. So sometimes it has a GPS signal, but it knows it hasn't transmitted the message successfully.

The SPOT device consists of a 1.6 GHz transmitter for the uplink to the satellite and a GPS receiver. There is no receiver to get a completion message. The SPOT handheld device transmits 3 times in the blind during a 20 minute interval. In the blind means that the device has no knowledge of reception so multiple transmit attempts are made to ensure one gets through. They figure if the device can receive GPS then the device is in transmit range to a Globalstar satellite.

manual
http://www.findmespot.com/downloads/SPOT_2_User_Guide_V2_printed_Oct8_2009.pdf


Website FAQs

Can I receive notifications or messages on my SPOT Messenger? No. The SPOT Messenger is a one way communication device


How quickly will a message go out after pushing a button? Once you have acquired a GPS fix, messages typically send out to their destination in 2 to 5 minutes
 
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