Tracking: How does it work? What is available?
You often hear terms ‘GPS tracking’ and ‘satellite navigation’. These terms are sometimes confused by consumers. ‘Satellite navigation’ refers to a device which provides turn-by-turn instructions to guide you to a destination. ‘GPS tracking’ refers to a device sharing your location, typically via a weblink, so remote viewers can see where you are.
We all commonly use the term “GPS”. GPS is the American satellite constellation of satellites which became live in 1993. Other constellations now exist too; in 1993 Russia launched GLONASS. China launched BeiDou in 2015, and The European Space Agency operates the Galileo constellation. For completeness, there is also the Indian Regional Navigation Satellite System (IRNSS), and Japanese QZSS which enhances the regional capabilities of GPS in certain parts of East Asia.
Most modern tracking and navigation devices do not rely only on “GPS”, they use “GNSS”, which means they can receive signals from some or all those other constellations.
A mobile phone, or a dedicated tracker calculates your position by “receiving” broadcast signals from those satellites. If your device has line of sight to at least 3 satellites, then it can calculate your 2D position (longitude and latitude). If your device receives signals from 4 satellites, then it can calculate your 3D position – this adds your elevation.
OK, now that your phone or tracker “knows where it is” in the world, it needs to 'send' that information somewhere i.e., typically to a server on the internet, which can be viewed or send your location to an expedition leader, family or other viewers. This is where the critical difference splits the devices. Most mobile phones are connected to one network (in the UK; EE, O2, Three, Vodafone). If your mobile phone is taken into an area where it has no signal, then it will be unable to send your location to the internet. This raises a key issue for safety.
Dedicated tracking devices sometimes use mobile signal to send their data, though many use multinetwork SIMS (sometimes refrred to as emergency SIMs). Some devices transmit directly to satellites and thus have no reliance on mobile network availability.
Should you use a tracking app or a dedicated tracker? This is a popular question, or you may often see a common argument, “Why should I use a tracker when I can just use my mobile phone and an app?” Let us look at what is available and the pros and cons of each.
Mobile Phone and a Tracking App
There are many mobile applications that will track your location and share it via a weblink. Some of these applications are free, and others have a one-off cost and/or a monthly subscription.
Strava Beacon is free-to-use without a Strava subscription, providing you carry your mobile phone with you to record the activity. If you want to use Strava Beacon via an Apple Watch or a Garmin device, then you will require a premium Strava subscription.
Once activated, Strava Beacon sends your location every 15 seconds to a unique weblink that you can share with your contacts. Your current location is shown on a Google map, along with the time of the last location update, as well as a breadcrumb trail of your recorded route. Your contacts do require Strava installed to see this information.
Other mobile Apps
Find My is free functionality built into Apple devices so you can share your location. Android Find My Device is the equivalent. There are also paid apps such as FollowMee, which have a small cost to purchase, and then there are various paid features you can unlock. All of these will share your location to a basic map in a similar way to Beacon.
Pros and cons of mobile app-based tracking
Free to use in most cases. Well, “free” in so far as you are leveraging the £300 to £1000 investment you made in a smartphone
Easy to use. Typically, use involves activating the sharing feature and this prompts an outbound SMS with a URL to your contacts
Accurate and “live”. Your location is updated often, usually every 15 seconds
planned route roams into an area of no mobile coverage, your location will not be shared until you emerge back into coverage
Use of tracking apps will run down your mobile phone battery much faster. Strava Beacon, broadcasting at 15 second intervals will deplete a phone after only a few hours use
Most free apps share your location on a basic map type, such as Google Maps, which lack the route and elevation detail shown on Ordnance Survey maps. It is not easy to discern if your location is a public right of way or otherwise
There are many dedicated trackers available to hire or buy. There are many cheap pet trackers available on Amazon, that frankly are very poor. Mosts respond to text messages with a Google Map or similar link, and performance is patchy.
There are also Apple AirTags, Android Tiles, Vodafone Curve (discontinued 2022), and similar devices. These devices are reliant on detection and proximity to another Apple/Android device via Bluetooth, then that device requires mobile signal to transmit its location. These websites do not offer OS mapping, or any mapping suited to serious outdoor use, and the nature of how they are detected severely limits use cases in the countryside.
Therefore, here we will discuss the three most popular types of dedicated tracker that are viable to use for expeditions; LTE (and older GSM), SPOT, and Iridium.
LTE Trackers (Note there are still some legacy GSM devices sold by suppliers too)
If you have ever been given a tracker to use on an organised mass hiking/running event, it will almost certainly have been an LTE (or legacy 2G GSM) tracker. These devices are fitted with a multi-network SIM card, so they will transmit on any of: EE, O2 or Vodafone, or Three (no 2G on Three). GSM only units will send your location via the old 2G band. Worldwide, some countries have already completely phased out 2G. The UK networks have announced that 2G is to be phased out from 2025. If you are in the market to hire or buy a dedicated tracker of this type, ensure it is one of those more recently manufactured that transmits on 4G LTE (they uses newer bands called - IoT and LTE)
LTE devices do not have a screen. They will transmit their location every minute or two, with a battery life of several days to several weeks. The update frequency can be set as low as 10 seconds, but the battery will expire in under 24 hours. Typically 2-minute location updates are best for expeditions, and afford a battery life of 6 days between charges. The devices are lightweight, usually under 100 grams. They are usually secured on the shoulder in a pouch or pocket. The batteries are fitted poly/lithium cells, usually charged from USB or by wireless charging. Their SOS button will usually trigger SMS to one or more contacts that you can specify.
Small, lightweight, under 100g
Lowest cost to hire or buy
They provide the fastest location updates (as fast as 10s)
They will work reliably under heavy tree canopy
Location can be sent to a 3rd party tracking platform and displayed on advanced maps (OS), and viewed alongside multiple other trackers (for example in a expedition or race)
Rely on the availability of some signal on any mobile network (Assuming it is fitted with a multi-network SIM)
Purchased LTE trackers require an active subscription (typically £10 a month)
Do not directly request a rescue service in event of SOS
A SPOT tracker transmits its location via the Globalstar constellation of satellites. There are 24 Globalstar satellites in orbit. One SPOT advantage is that they are not reliant on mobile networks. However, there may not always be a Globalstar satellite in line of sight for a successful location transmission so updates can sometimes be infrequent. SPOTs work in most areas all over the world with the following exceptions: no coverage in the Polar regions, and intermittent coverage around the equator and some oceans. SPOT do not transmit under tree canopy or anywhere they are unable to get line of sight to one of the 24 satellites in their constellation; this can include hilly/steep sided terrain and valleys; for example, you may not receive a location update every 5 minutes whilst on the slopes of Lake District or Snowdonia mountains.
SPOT Trackers can send preset OK, Custom or Help messages, and have a dedicated SOS button that contacts a rescue centre in the United States. They use 4 x AAA batteries which typically last a couple of weeks, depending on use.
Excellent battery life, replaceable batteries
Fairly small and lightweight; around 150g
Do not require mobile network to transmit their location
Dedicated SOS button for emergency rescue
Only send one update every 5 minutes unless you pay more (circa £100 a year for 2.5 min updates)
Require line of sight to satellite (do not work under trees, and have limited cover near steep terrain)
Does not provide 100% global coverage
Purchased SPOT trackers require an active subscription (typically £20 a month on a flexible contract), plus annual flex fee.
Location data is not buffered/stored on the device if it is unable to transmit on schedule; instead the location point is “forgotten”
SPOT maps are basic (no OS maps). However, their location data can be sent to a 3rd party (paid) tracking platform and displayed on advanced maps (such as OS), and viewed alongside multiple other trackers (for example in an expedition or race)
Popular examples of such devices are Garmin inReach, and Yellowbrick. These trackers transmit location via the Iridium constellation of satellites. There are 82 of these in orbit, providing 100% global coverage, significantly better than SPOT. Iridium devices still require line of sight, so may not work under heavy tree canopy, though with more satellites on orbit they are more reliable under tree cover and in hilly areas than SPOT devices. This reliability is reflected in the high cost of purchase and the high cost of Iridium satellite data plans. Many Iridium devices are also two-way SMS and email communicators. Either natively, using the device scfeen menu to tap out messages, or by connecting a mobile phone via Bluetooth. The user can send preset or freeform SMS to any mobile phone (or another Iridium device), and they can also send email and in some cases update social media. Some devices have screens and mapping, so can provide full navigation, and can also receive weather reports. Iridium’s have a dedicated SOS button to request rescue from a (Garmin owned) US based first-response centre.
Iridium devices usually have a fitted lithium battery, which can last 2-14 days, depending on model, if screen use is minimized.
100% global coverage
Smallest device weighs 110g (inReach Mini 2)
Feature dedicated SOS button for emergency rescue
Two-way messaging capability
Some models have navigation and weather reports
Only send one update every 10 minutes unless you pay more
Some YB and Garmin devices weight 300g or more
Require line of sight to satellite
Battery can last as little as one day on some devices with larger screens
Purchased Iridium trackers require an active subscription (typically £40 - £90 a month on a flexible contract)
Garmin Manufacturer maps are basic (no OS maps). However, location data can be sent to a (paid) 3rd party tracking platform and displayed on advanced maps (OS), and viewed alongside multiple other trackers (for example in a race)
If you are out in a local urban area, or an expedition or hike of a few hours in length in an area with good mobile coverage, use your mobile phone with an app such as Strava Beacon.
If you regularly expedition in rural areas (National Parks including The Lakes, Peaks, Dartmoor, Exmoor) most of your route enjoys cpverage on at least one mobile network, an LTE tracker is the best choice in terms of performance and value of for money.
If you exclusively hike in the most remote valleys of the Cairngorms, Brecon, Snowdonia, where larger gaps in mobile coverage persists (time of writing late 2023) then a SPOT device can be useful, as long as it is placed horizontally on the shoulder, and afforded a perfect sky view.
If money is no object, and you want the most reliable tracking and communication, including two-way SMS, then choose a Garmin inReach device with a 3rd party OS mapping provider like ourselves.