How are messages relayed to the network?
All messages sent from SPOT are sent to Globalstar network of satellites.
Iridium, Globalstar? Weren't these technologies too early for their prime?
You may have heard or even used one of the satellite phones. The bandwith was the most limiting factor at the time. SPOT uses the low speed data channels (AKA the Simplex channels) on the Globalstar satellites. It does not use the voice channel! This simplex system has always been part of the Globalstar system, in all generations, present and future. Globalstar created SPOT in part to demand and in part to make better use of the very underutilised data bandwith.
Globalstar Simplex Data and Asset Tracking Services - Fully Operational
The Globalstar constellation is completely stable and fully operational in supporting Globalstar Simplex data satellite products and asset tracking services. Recent monitoring tests indicate that the Simplex data network is currently operating at a successful transmission rate of greater than 99 percent. And because Globalstar's Simplex data products are also designed to work with the second-generation satellite constellation, they are expected to provide customers with years of high quality reliable service well into the next decade and beyond.
Globalstar Satellite Data Coverage Expands
Globalstar has recently expanded its satellite Simplex data coverage to include all of Alaska, the Aleutian Islands and the surrounding maritime regions including the Gulf of Alaska and portions of both the north Pacific and south Arctic Oceans. The expanded Simplex data coverage, which is available on six continents, is the result of an applique hardware installation and software upgrades at the Globalstar satellite gateway or ground station located in Wasilla, Alaska.
How can the GPS operate on two AA batteries and still have decent reception?
transmitter within the unit is a major power consumer when the messages
are being transmitted to the satellite. This resulted in the other parts
of the unit having to be extraordinarily power efficient to compensate.
The GPS subsystem in the SPOT uses an infinitesimal fraction of the
power than the equivalent subsystem in a hand held GPS navigator uses.
SPOT is designed to be extremely power efficient. That's why it can send so many messages on one set of two AA batteries. The downside is that it only turns on the GPS receiver when it needs to send a message; therefore, you're not going to get constant reassurance that you have good GPS position data. Since it doesn't have a Globalstar receiver, no acknowledgment can be sent back to indicate that a message was transmitted successfully as was pointed out earlier.
So the GPS turns off between transmissions?
The unit puts the GPS chipset into a "standby" mode between transmissions to save battery power. In this standby mode the Real Time Clock still runs and the ephemeris and almanac data are retained. As a result, after a shut off of only 10 minutes, the restart is what is known in the GPS world as a "hot start", and assuming the GPS signal strengths are at all trackable, it re-acquires them in about 1 - 5 seconds.
Full description of the GPS receiver and transmitter sequence
The GPS receiver is turned off unless SPOT needs to send a message. The messaging sequence begins by turning the GPS receiver on long enough to establish a location, after which SPOT turns the GPS receiver off and keys the uplink transmitter. The receiver stays off until it needs to send another message.
What GPS chipset does SPOT use?
NemeriX, a semiconductor company specializing in ultra low power GPS provides its NX2 system as the GPS solution for the SPOT Satellite Messenger. Link to the press release.
When does SPOT need extra time to acquire GPS coordinates?
If the unit hasn't obtained new almanac data from the GPS satellites for more than 30 days or, the unit has been moved more than about 200 kilometers since the last time it obtained a fix.
How can I ensure satellite reception?
The Globalstar satellites are moving around in the sky. For a message to go through, at least one satellite has to see your SPOT, and see one of the SPOT ground stations! What this means is: if you've got a great horizon-to-horizon view of the sky, and you're not too close to the edge of the dark orange area in the coverage map, almost 100% of your "track", "help" or "911" messages will get through. If you have only a partial view of the sky, or you're starting to get near the edge of the dark orange area of the map, the condition of a satellite being in view of both your SPOT and the ground station happens somewhat less often, so fewer of your messages will get through.
More details on message transmissions
The "check in" message actually transmits three times. It transmits in the following pattern: As soon as the SPOT has a GPS fix it transmits, then 5 to 10 minutes later (randomly dithered) it transmits a second time, then 5 to 10 minutes after that (random again), it transmits a third time. These three transmissions all have the same internal packet ID which causes the SPOT back office to throw out the duplicates and only send one to the emails and mobile-phones on your check-in list. Again, it is a triple redundant packet. All messages are identical and contain a location from right after you activated check in mode.
What is considered a transmission obstruction?
Frequencies around 1600 MHz go through most plastics, rubber, glass, and most fabrics (cotton, wool, polyester, nylon, most other synthetics) with almost no attenuation. Wood between the SPOT and the sky is a no-no. Wood will attenuate the signals quite a bit. A thick canopy of leaves also attenuates those frequencies a lot. Your body, and almost anything containing water also attenuates the signal a lot. Metal, concrete, stone, asphalt, brick, earth, between the SPOT and the sky will kill the signal completely.
How does the unit handle temporary obstructions?
The unit does "track"
certain metrics that give it "confidence" in the GPS accuracy. If it
sees a down-tick in overall confidence, it usually will wait up to a few
seconds for the confidence to get better (many variables in the
algorithm). In the situation described, in simplified terms, it would
usually postpone the transmission for a few seconds.
However, if it has a fix at all, it has "bail out" criteria that will transmit whatever it has eventually (well within the 10 minute window between messages in Track mode or the 5 minute window in 911 or Help modes) even if the various "confidence criteria" metrics are failing to settle down.
If it is "time to report" (10 minute interval in track, 5 minute in 911 or help), and it gets a fix, and just before it transmits the GPS signals disappear entirely, it will wait a few seconds, then if the signals don't return, it will transmit the last GPS co-ordinates it had.
How do I know when it's done sending messages?
Simple, the "ok/check" LED stops blinking! So, it's best to send check-in messages from your base camp, or when you've stopped for a few minutes to admire a view. Activate check-in mode and leave the SPOT sitting with it's face to the sky until the ok/check LED stops blinking.
What is the likelihood that a message won't get through the first time?
Since the satellites are moving around, time is your friend. If at one moment in time, there is no satellite in a "good" position for you, the odds are very good that 5 - 10 minutes later one will be! So, since the check-in message is actually transmitted three times, throughout most of the US and Canada the probability that the check-in message will get through is around 99.99% (you'll miss something like 1 in 10,000). The likelihood that at least 1 out of any given 3 consecutive help, 911, or track messages will get through is about the same.
Where should I keep the unit in a vehicle?
It will work inside of just about any non-metallic enclosure. In a car, dashboard has worked great and some reported good throughput from the glove compartment. On a motorcycle it should track you just fine inside of a saddle bag. Many Honda Goldwing riders carry their SPOT in the front pocket and report excellent transmission rates.
Should I use the belt clip when hiking?
For best message transmittal rates, the SPOT logo on the unit should be pointing to the sky. Try to place the SPOT horizontally in your backpack.
Does it help to tilt the device somewhat toward the south?
Maybe, but be careful not to overdo it. The radiation pattern is very broad. With the unit flat on it's back, the pattern is quite even in a cone from about 10-15 degrees from horizontal to 90 degrees straight up. So, if you tilt it more than 10 - 15 degrees, you're doing little more than sending potentially useful RF energy into the ground.
Can I connect an external antenna to increase likelihood of the transmissions?
There is no provision for an external antenna. The impedance match and line-loss requirements for the satellite transmitter are extremely critical. Most do-it-yourself wired antennas wouldn't work because of this.
Any chance to eliminate the batteries and hook it up directly to a 12V car adapter?
There is no know solution at this time, for a couple of reasons. First, it would compromise the waterproof features of the unit. Second, cars operate on 12V, SPOT on 3V. If you hear about a solution, let me know!
Why are lithium batteries required for proper operation?
Alkaline batteries can
be used in need when lacking other options. Alkalines do not perform in
high drain situations below freezing (32 degrees F) and even fresh
alkalines behave like they're nearly dead below about 40 to 45 degrees F
or so. The lithiums, on the other hand, put out enough current to
operate the SPOT correctly down to -22 degrees F (-30 degrees C)
throughout their entire useful life and down to -40 degrees F (-40
degrees C) when they are fairly fresh.
Second reason is the power discharge curve. Lithiums discharge in an almost perfectly flat line, while alkalines suffer from linear decay of voltage. The transmitter in the SPOT must be provided with 3 volts to function properly.
How do I know my OK message is being sent?
After activating the OK message, the light will stay on for 5 seconds once the message is transmitted.
What about the HELP feature?
Upon activating the HELP feature, the unit attempts to send a message every 5 minutes for one hour. See the tips on best transmission positioning.
How do I turn off the Help or 911 feature?
Hold down the respective button (Help or 911) for 5 seconds. The red flashing light means it is coming out of the mode. If you let it sit for a short while, the red light should stop blinking and the unit will go back to just being "on" and not in any transmitting/tracking mode.
How often does each type of message get sent? Does that include the GPS location?
Help, 911, and Track
update the position with each transmission.
Help transmits every 5 minutes for one hour (total of 13 transmissions).
911 transmits every 5 minutes forever (until canceled or powered off, or, of course, if the batteries die).
Track transmits every 10 minutes for 24 hours.
Uh, I think I accidentally hit the 911 button!
Oh, you just seriously charged yourself a minimum $345 /hr. false alarm fee.
More on accidental 911 activation as advised by a company representative.
If someone knowingly accidentally hit the 911 button they can push it and hold it for 5 seconds and it cancels the call.
How does the tracking feature work?
Tracking sends a message to SPOT offices every 10 minutes. Your time and location is then recorded in the database for you to view later or to share on a public page with your family and friends. Once you have the unit turned on and in tracking mode, it will send a position report every ten minutes for 24 hours. After 24 hours the tracking must be enabled again.
Is the time period when automatic tracking messages are sent configurable?
No. At the moment, the unit attempts to send the message every 10 minutes.
How do I turn off the tracking mode?
Hold down the OK button for 5 seconds. The red flashing light means it is coming out of tracking mode (or coming out of 911 mode, or Help mode, if that's the mode you were in). If you let it sit for a short while, the red light should stop blinking and the unit will go back to just being "on" and not in any transmitting/tracking mode. You can also terminate tracking mode by simply turning the unit off.
What is Public Sharing?
If you enable public sharing, the tracking data is saved for 24 hours and mapped using Google Maps. Anyone with the public web site address can access the page without logging in and see your progress.
So anyone can see my tracks?
You can create a publicly shared page with or without a password. The page without a password is accessible to anyone that has the web site URL.
Doesn't the page get cluttered?
Mapping the location every 10 minutes can get a bit crowded. The publicly shared page only displays the data from the last 24 hours. You as the owner can retrieve historical data beyond the 24-hour limit.
Can I create more than one page?
A maximum of 10 links can be created in your online profile.
Why am I getting "Too Many Pageviews" error on my publicly shared page?
Each link can have 500 visits per week, after which, the link will no longer work until the following week.
I am popular and want people to track my progress!
Check out the Spot Trip Manager by Jason Jonas. His application parses emails received every time you hit OK on the SPOT. The SPOTcasting messages sent by your unit are not displayed.
Does the address for my publicly shared page change each time I enable the feature?
The address for the shared page stays the same. If your unit has not sent any tracking messages in the last 24 hours, the web page will display "No new messages within the last 24 hours".
Odds and ends about Public Sharing.
If you change the custom message for your OK or Help messages after you have created the public page, the page will continue to display the older custom message. You will have to create another public page to have the updated messages. This will also result in a new publicly shared link address.
How do I contact SPOT Customer Care?
SPOT Customer Care can be reached on 0424 217 768 from Australia. This number is forwarded to the US.
The SPOT Customer Call Centre
hours are Monday to Friday 8am till midnight (USA Eastern standard
time). This is 10pm through to 2pm the following day Australian Eastern
Time. For Australian Western time this is 8pm through to midday the following day.
Outside of these hours customers are asked to leave a message, or alternatively customers can send emails which are typically answered within 48 hours. Their email address is firstname.lastname@example.org