Speeds and Feeds

I've written here before about emergency locators, those gizmos that can help rescuers find you if you become lost in the wilderness.

The tragic death of CNET's own James Kim and the disappearances of Microsoft's Jim Gray and famed adventurer Steve Fossett have convinced me that anyone who travels outside populated areas ought to carry one of these devices.

The SPOT Satellite Messenger is the first of a new class of emergency locators.

(Credit: SPOT)

Following that earlier post, I was contacted by SPOT Inc., makers of the SPOT Satellite Messenger, which began shipping through major outdoor retailers this fall. They offered me a SPOT messenger for review, and I happily accepted. It arrived in November, but my testing was interrupted by a minor injury that kept me from getting a complete picture of the gizmo's performance.

My doctor pronounced me healed after I returned from my Christmas vacation, so on New Year's Day I spent four hours clambering over the Santa Cruz Mountains in California's Castle Rock State Park, a beautiful wilderness area located just six miles or so from my house-- though it takes most of a half-hour to drive there up scenic State Routes 9 and 35.

Castle Rock's major trails stretch along the sides and top of heavily forested mountain ridges, as you can see in the park brochure. I figured these trails would provide a reasonably challenging testing ground for the SPOT messenger, which is unique among low-cost locators in combining satellite location through the Global Positioning System and satellite data reporting over parent company Globalstar's network.

The SPOT messenger also has another unique feature: it's useful even if you're not in trouble. Traditional PLBs (Personal Locator Beacons) can only be activated in case of emergency; all they do is send a short message to the Cospas-Sarsat network, at which point the appropriate SAR (search and rescue) organization is contacted.

SPOT adds three useful new capabilities:

• You can send a simple "Check in" message to a list of SMS and email contacts.
• You can send "Track progress" position updates every ten minutes that can be viewed through a Web browser.
• You can send a "Help" message for less than life-threatening situations to a second list of SMS and email contacts, perhaps requesting them to contact you or send less urgent assistance.
• And if your life is threatened, there's a "911" feature that will call in the cavalry just like a PLB.

But while all this is great in theory, it's no help if the SPOT gizmo can't talk to the Globalstar satellites, and that's what I wanted to test.

When I got the unit, I installed the provided lithium AA batteries (it'll operate on alkaline batteries, but not in cold weather, and not for as long-- so use lithiums), started the "Track progress" mode, and put the unit on my back patio. It's a small patio with a clear view of the sky overhead and in two directions, but the house on one side and tall trees on the other restrict the view significantly. I sat back with my web browser and waited. Sure enough, after a while, position updates started coming through... but not every ten minutes. Some were clearly getting lost.

I moved the unit up to the roof of my house where the sky view is entirely unrestricted and left it running there for about a day and a half. This produced much better results, but still, perhaps ten percent of the updates went missing.

That weekend I drove down to the Los Angeles Auto Show (which I wrote about here) with the SPOT messenger on the dashboard, tracking my progress both ways. That produced similar results-- the vast majority of the updates came through. (I'd include an image of the track from the SPOT website, but I don't want anyone calculating my average speeds over all those ten-minute intervals. :-)

But when I went to Castle Rock on Nov. 20 and spent about 90 minutes wandering around, I got only one position report back. For about half that time, the messenger was riding on my belt; for the other half, it was riding on top of my backpack. It should have had nine opportunities to send a report, but apparently the tree cover was enough to block almost all of the attempts.

Thanksgiving followed, and I got that little injury the next week, so New Year's was the very next opportunity I had to give the SPOT messenger another chance.

I was out of the house from about 12:30pm to about 5:30pm. I started the SPOT tracker mode in the driveway before I left, and happened to get another location in the driveway just as I returned. In between, I drove to Castle Rock (about 25 minutes each way) and walked around for about three hours with a 45-minute break in the middle and a few rest stops along the way in spots that seemed more likely to allow the satellite connection to work.

During my time walking on the trails between 1:05pm and 4:55pm, there were 23 opportunities for the SPOT messenger to transmit a position report. Eight of them got through. Four were during my break at the Castle Rock campground, where I rested away from any trees, giving the unit a score of 21%-- four successes out of 19 opportunities-- on the trailwalking part of this test. The image here shows how position information is reported using Google Maps; a tabular form is also available.

Position reports can be viewed on the SPOT website using Google Maps.

(Credit: Peter N. Glaskowsky)

SPOT's documentation does say that the messenger needs a clear view of the sky to operate properly, but some of the company's marketing materials are not so clear. For example, the company's page on network coverage identifies areas where there is a "99% or better probability of successfully sending a single message within 20 minutes," but it only mentions "hills and buildings" as possible problems. I think SPOT should change this to say "trees and buildings" since trees are more likely to be a problem than hills.

If you're hiking in areas without heavy tree coverage or deep canyons, the tracking function should work fine. If a SPOT user happens to get injured or trapped without that clear view of the sky, they'll need a hiking buddy to carry the messenger to a better location before sending the 911 call. (Or a good throwing arm; the SPOT messenger is pretty stoutly built, so that might actually work if you have no other way to save yourself.)

Okay, on to some design critique. The SPOT messenger's user interface is awful. The unit has four buttons and four LEDs. Pushing the ON button turns the unit on. So far so good. Pushing the OK button once sends a single message. The Help and 911 buttons work as expected. But... to engage the tracking function, you have to push and hold the OK button for five seconds, except this doesn't work if the unit is still trying to send another message; you have to turn the unit off and back on. The LEDs blink separately or together depending on whether the unit is getting a GPS signal.

There's no way to know if the messages aren't getting back to the Globalstar network since the SPOT messenger uses a one-way transmitter. I'm sure this limitation is part of how SPOT got the price of the gizmo down to $149.95 ($159.95 direct), but it's a potential problem for a life-saving device.

This would be a good place to add that the SPOT messenger also requires a service plan-- $99.99/year for basic service, another $49.99/year for the "Track progress" feature, and $7.95/year for traveler's insurance including international evacuation assistance from partner company GEOS (details here).

In my testing, I was able to come up with several ideas for improving the messenger's user interface as well as the reliability of the service. (SPOT, if you think any of these ideas are patentable, give me a call!)

• The OFF button needs to act like a Cancel button at all times.
• Activating a new function shouldn't be blocked by some currently pending function.
• The unit needs one separate LED for each major function: power on, GPS tracking, and transmitting to satellite.
• Each LED should show green for normal operation, amber for a temporary fault such as low battery or a loss of the GPS signal, or red for a hard fault.
• GPS signal strength should be used as a proxy for Globalstar satellite availability: if the GPS signal is weak or absent, the unit should save and retransmit the current data packet. The weaker the signal and the more important the message, the more frequent the retransmission should be in the hope of finding a gap in trees or other obstructions. Only when the GPS signal strength indicates clear skies can pending messages be assumed to have gone through.
• Position reports should include altitude information. Accidents are more likely in steep terrain, and it can be vitally important to know whether the user is at the top or bottom of a cliff.
• 911 alerts should also go to the Help contact list, with a message indicating the severity of the alert.
• In addition to allowing customization of the Help message, SPOT should allow the user to customize the 911 message. I carry an amateur radio when I'm out hiking; it could save a lot of time if the SAR crews know I'm usually monitoring the 2-meter national simplex calling frequency of 146.52 MHz.

But don't get me wrong, I think this is a great device, a big step forward over previous-generation PLBs. In future products, I'd like to see compatibility with the 406 MHz Cospas-Sarsat network for 911 calls, two-way satellite communication that would eliminate most of the problems described above, and local display of GPS coordinates for hikers who primarily use a map and compass and don't wish to carry a separate GPS receiver. Full integration with a GPS mapping device would be nice for some users, but keeping the SPOT functionality separate has some reliability advantages.

Bottom line: if you ever travel off the beaten path, you should get a SPOT messenger. Keep it in your car or backpack. Replace those lithium batteries every couple of years. It could save your life.