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Satellite Communication: Can a GPS unit help you get rescued? (Part 2)

In the intro to this series on Satellite Communication, I did a brief overview of what’s out there now to communicate through satellite.

There are GPS which help you navigate but not communicate, there are 1-way and 2-way satellite messengers that let you send small messages, and there are satellite phones for voice calls and text over satellite.

We’ll be looking at GPS in this article, what they do and what they don’t do.

To start, we need to look at what a GPS is. After that we can compare it to the other devices.

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What is a GPS?

A GPS is an electronic device that shows your location on a map. You probably have a GPS in your phone. You might have one in your car. You might take one hiking with you. It shows your location on a map and where you’re going. Some of them show where you’ve been with a breadcrumb trail.

GPS talk to the satellites to figure out where you are on the planet. They do a bunch of math and show your location on the map. You can use them to navigate to a destination like a mountain or lake. Most GPS can show topo or other maps at the same time. They put your position on the map then you can see how far you are from the mountain or trail.

You can also put other things on your GPS like points of interest or old GPS tracks from you or other people. A point of interest might be a really nice viewpoint or a good place to have lunch. Download that file from the internet or copy it from a friends computer and then put it on you GPS. Now you can follow the GPS to get to exactly the same place again.

Most GPS also take a breadcrumb or GPS track of where you’ve been. You can put this track on your computer after the hike and see exactly where you’ve been. This can be really useful if you’re keeping track of the trails you’ve been on, you want to give the track to someone else after, or you want to see the track on a computer after. Drag the GPS track into Google Earth and see exactly where’ve gone and how close you came to where you wanted to go!

In terms of hardware, GPS have a screen to see the map, some buttons to control what you are seeing and an antennae to talk to the satellites. Screens can be small and black and white or large, colour touchscreens.

GPS need large antennae to talk to the satellites. More expensive GPS have better antennae and get better reception. Trees and canyon walls will limit how many satellites the GPS sees and reduces the accuracy of your signal. Low connectivity is like having only 1 bar of reception on your phone. The more satellites the GPS can see the better it knows where you are. More satellites means the GPS can pinpoint your location down to within 3 metres. If the GPS can’t see many satellites then it might only be within 50 or 100 metres.

So a GPS shows your location on a map. That’s basically all it does. It’s simple but can be very helpful when you don’t know where you’re going or the weather makes it hard to see. Now we get into what the difference is between a GPS and a satellite communication device.

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Differences between GPS and other satellite communication devices

So we looked at GPS in the previous section. They can’t send anything like a text message or email to other people. They only show your location on a map so you know where you are and the the mountains, lakes and trails around you

Satellite messengers, personal locator beacons and satellite phones, on the other hand, can send messages out to other people. Some can text or email, some phone. Personal locator beacons send a message straight out to emergency authorities to come rescue you.

The line is getting blurry between what is a GPS and what is a satellite messenger.

Delorme put a GPS together with a satellite messengers in their inReach SE and Explorer. Since then Garmin bought them and added better GPS.

GPS are designed for navigating and following trails. They are good for following a GPS track or making a breadcrumb which you can look at after your hike on a computer or share with friends. Unless they have a satellite messenger built in, they  don’t communicate with the outside world like the messengers do so they won’t help you get rescued.

The things that can help you get rescued are the ones that can connect with the outside world: satellite messengers, satellite phones, and personal locator beacons.

In the next article (coming out soon) we’ll talk about a couple of good satellite messengers, the SPOT and InReach.

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There are 4 parts to this series:

  1. Intro: Satellite Communication 
  2. GPS: Can they get you rescued? (this article)
  3. Spot vs InReach (coming soon)
  4. PLBs and Sat Phones (coming soon)

 

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