SPOT Global Messenger

[SpotMaker]

Thanks Rodie, I was just looking at the possibility of dual purpose. You know the marine/fishing community could really grab this and run also. It could be a saver as a last location and direction of travel on the water, in the event of a sinking?

Marine applications are indeed one area for which we are marketing the SPoT heavily.

The GEOS 911 center is fully equipped to dispatch the Coast Guard or whatever relevant marine rescue agency is applicable to the area a 911 signal might come from on the water.

You simply have to be within the footprint shown on the map that Roadie posted above.

SPoT's should be showing up on the shelves of West Marine stores about this weekend. Or this coming week, at the latest, from what I've been told. (West Marine purchased quite a few of them.)

 

[Desertoutpost]

Marine applications are indeed one area for which we are marketing the SPoT heavily.

The GEOS 911 center is fully equipped to dispatch the Coast Guard or whatever relevant marine rescue agency is applicable to the area a 911 signal might come from on the water.

You simply have to be within the footprint shown on the map that Roadie posted above.

SPoT's should be showing up on the shelves of West Marine stores about this weekend. Or this coming week, at the latest, from what I've been told. (West Marine purchased quite a few of them.)

Thanks for the info, I was just at a tackle show and talked about your product with other sponsored fisherman, They liked the sounds and we all tourny/fish local water within the footprint. Just thought I might get the word out!

 

[benedmonson]

Used mine on tracking mode from Denver to Telluride today to see how it works before leaving with it for Belize and Guatemala! It worked and tracked great setting on my land rover dash with a view to the sky.

Only 1 problem, the gmt times are way off!! Is the a setting in my preferences to change the time??? I searched everywhere and found nothing.

Love the SPOT!!!

 

[TheRoadie]

One of my dozen feature requests was to add a configurable time zone for the hits. When you say "off", can you quantify it? Definitely call customer support and report it, since it may be their time stamps are not synced to a time server like they should be.

 

[Willman]

Wow....Great thread!

Lots of great infor.!

Looks like a cool product.......going to have to check Kurts out during one of the SLC meet n greets.....

 

[SpotMaker]

Only 1 problem, the gmt times are way off!! Is the a setting in my preferences to change the time??? I searched everywhere and found nothing.

It took me a moment to figure out where this complaint might be coming from since the messages are timestamped at the ground stations and the ground stations have a clock synced to GPS signals.

Then, it occurred to me where your perception of the time being "off" might be coming from:

In track mode:

For a myriad of technical reasons, some of which are proprietary, it reports nominally every 10 minutes. There is some slop, or what we call "dither", in the reporting rate. So, if you were expecting a report every 10 minutes to the exact second, you're not getting it. It's every 10 minutes plus-or-minus a couple of minutes.

In check-in mode:

The "single" check in message is sent as a "triple-redundant-burst". That is, the identical message is sent three times over a 10 - 20 minute window. This is done to make sure the message gets through. If there wasn't a satellite with a good angle on both you and the ground station for the first message, odds are very good that there will be one in a good position for the second or the third.

In check in mode, the back-office only relays out the first message received of the three. It identifies the redundant messages as redundant.

So, in check in mode, it's possible that the message that actually gets received was sent up to 20 minutes after you hit the check-in button. The time stamp is very accurate. It is the message itself that was delayed.

In the other modes, help, 911, and track, the messages are not sent redundantly. A new, unique message is sent every 5 minutes (help and 911) or every 10 minutes (track) and the back office sends through every one it gets.

Love the SPOT!!!

Thanks!!

 

[benedmonson]

It took me a moment to figure out where this complaint might be coming from since the messages are timestamped at the ground stations and the ground stations have a clock synced to GPS signals.

Then, it occurred to me where your perception of the time being "off" might be coming from:

In track mode:

For a myriad of technical reasons, some of which are proprietary, it reports nominally every 10 minutes. There is some slop, or what we call "dither", in the reporting rate. So, if you were expecting a report every 10 minutes to the exact second, you're not getting it. It's every 10 minutes plus-or-minus a couple of minutes.

In check-in mode:

The "single" check in message is sent as a "triple-redundant-burst". That is, the identical message is sent three times over a 10 - 20 minute window. This is done to make sure the message gets through. If there wasn't a satellite with a good angle on both you and the ground station for the first message, odds are very good that there will be one in a good position for the second or the third.

In check in mode, the back-office only relays out the first message received of the three. It identifies the redundant messages as redundant.

So, in check in mode, it's possible that the message that actually gets received was sent up to 20 minutes after you hit the check-in button. The time stamp is very accurate. It is the message itself that was delayed.

In the other modes, help, 911, and track, the messages are not sent redundantly. A new, unique message is sent every 5 minutes (help and 911) or every 10 minutes (track) and the back office sends through every one it gets.



Thanks!!

Spotmaker, thanks for the explanation, but yesterday during a long track the times were like 7 hours ahead of the actual mountain time where I was performing the track??? Let me know if you need to log into my account to see what I'm talking about.

 

[TheRoadie]

..7 hours ahead of the actual mountain time ...

Ummmm, GMT (greenwich mean time, also called Zulu time) is 7 hours ahead of MST.

SpotMaker - in the case of a small difference, on the order of 1-20 minutes, I was going to guess your explanation was the right one. What I was hoping for, but I didn't get this wish for Christmas, was that the MESSAGES were time stamped by the portable unit and the time stamp was part of the message. Then we could have written display software ourselves from the lat/long/time stamp data to infer ground speed. If the time stamp is added upon receipt by the ground station, then that's impossible. Sigh... Too many bits for the burst, I suppose.

I could have guessed this earlier if I had looked at the time stamps in track mode more carefully. Still a wonderful product, but it does mean that sending messages at pre-arranged times as another way to add data to a series of transmissions (i.e.: my earlier morse code idea) needs to have the bit rate slowed down to take into account the dither and unreliability of reception.

I'm sure you debated adding the time stamp to the message that's uplinked. Can you share anything about the reason it isn't being done?

 

[SpotMaker]

Ummmm, GMT (greenwich mean time, also called Zulu time) is 7 hours ahead of MST.

<snip>

I'm sure you debated adding the time stamp to the message that's uplinked. Can you share anything about the reason it isn't being done?

It was a simple matter of prioritizing which data to pack into the single data packet. (Having all the data in ONE packet was a non-negotiable item for maximum reliability.) Obviously, since the SPoT contains a GPS receiver, it has access to an extremely accurate time internally, but that data didn't fit in the outgoing message with other data we wanted to put in.

The SPoT is not intended as a device to precisely time speeds etc. It's primary function is as an emergency beacon, with tracking and an "I'm OK" message added as useful and fun extras.

When you need SAR, SAR will be dispatched as soon as a 911 message is received, you really don't care if the timestamp on the messages is to the exact second, as long as SAR comes ASAP.

Similarly, when your wife gets a check-in message, she probably doesn't care about the exact second you sent it. She just wants to know you're OK and maybe see where you are on a Google map.

Next topic:

I also missed that benedmonson's concern was that the timestamps were in GMT and therefore 7 hours ahead of his local time (MST). Since a person may well be tracking himself across multiple time zones in a single trip, the decision was made to report all times in GMT to keep it simple. I suppose an option to report in whatever time zone the user wanted wouldn't be that hard to implement. However, as I've mentioned, I have nothing to do with the web site, nor do I have any influence whatsoever over it.

 

[TheRoadie]

...However, as I've mentioned, I have nothing to do with the web site, nor do I have any influence whatsoever over it.

Thanks for the details. You're certainly right about not wanting to compromise the primary mission of the device by feature creep. BTDTGTTS. That you discovered ExPo and came here to help us understand the device, and Globalstar (to date) has not, says a lot. Thanks for joining the party!

 

[benedmonson]

It was a simple matter of prioritizing which data to pack into the single data packet. (Having all the data in ONE packet was a non-negotiable item for maximum reliability.) Obviously, since the SPoT contains a GPS receiver, it has access to an extremely accurate time internally, but that data didn't fit in the outgoing message with other data we wanted to put in.

The SPoT is not intended as a device to precisely time speeds etc. It's primary function is as an emergency beacon, with tracking and an "I'm OK" message added as useful and fun extras.

When you need SAR, SAR will be dispatched as soon as a 911 message is received, you really don't care if the timestamp on the messages is to the exact second, as long as SAR comes ASAP.

Similarly, when your wife gets a check-in message, she probably doesn't care about the exact second you sent it. She just wants to know you're OK and maybe see where you are on a Google map.

Next topic:

I also missed that benedmonson's concern was that the timestamps were in GMT and therefore 7 hours ahead of his local time (MST). Since a person may well be tracking himself across multiple time zones in a single trip, the decision was made to report all times in GMT to keep it simple. I suppose an option to report in whatever time zone the user wanted wouldn't be that hard to implement. However, as I've mentioned, I have nothing to do with the web site, nor do I have any influence whatsoever over it.

I've got no problem with the time stamp being GMT. I was just making sure that I wasn't missing a time zone setting in preferences.

 

[Scott Brady]

All is well

All is well with Expeditions West
Unit Number: 0-7340750
Latitude: 34.5921
Longitude: -112.4346
Nearest Town from unit Location: Ninta Dr, Prescott, AZ, US Distance to the nearest town: 0 km(s) Time in GMT the message was sent: 12/04/2007 21:30:28
http://maps.google.com/maps?f=q&hl=en&geocode=&q=34.5921,-112.4346&ie=UTF8&z=12&om=1

Yes, all is well, as this is one of the coolest tools I have seen in a LONG time.

 

[AlaskanFlightMedic]

Found my SPOT

Just picked up my SPOT this last weekend at the REI in Anchorage and after a wee bit of issues with setting up my account (still don't know what happened) I was finally able to try it tonight. From the time I sent the OK message there was barely enough time to get in the house, go upstairs and check my email before I received the message. That said I am in Anchorage we will see how it works out in the bush. I bought this for my wife and I when we overland in the jeep but I am seriously looking at it to recommend to my flight service as a means of knowing when we are at a particular village while we are on Medevacs way out in the bush....I will get back to you once I test it. Additionally the map on the website outlining the coverage area seems to be rather dated. From what I have gathered the SPOT is on the GlobeStar Satellite System and if you go to their website there seems to a be a more current map.

 

[Luke]

Just throwing it out there, but what about shielding the 911/Help button somehow to make it idiot proof so you're not accidently putting out a distress beacon if it gets bumped inside your bag or something. It may be something as simple as molding the case with little walls around the button...any thoughts?

 

[SpotMaker]

From what I have gathered the SPOT is on the GlobeStar Satellite System and if you go to their website there seems to a be a more current map.

The map on the SPoT website is current as of 11/01/2007 (and the coverage hasn't changed since then). It was updated to coincide with the launch of the SPoT. (This is the Globalstar Simplex coverage map.) The map combines theoretical coverage with tens of thousands of experimental transmissions from SPoTs, especially in the fringe areas.

The Globalstar Simplex coverage (that SPoT uses) and the voice coverage (which you are looking at on the Globalstar website) are not the same. They do not exactly overlay.

That being said, I really look forward to your reports as to how well it works in the bush of Alaska.