How to Choose a Personal Locator Beacon or Satellite Messenger

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Article By:
Chris McNamara and Matt Gerdes

Last Updated:
August 28, 2017
Should you buy a satellite messenger or a personal locator beacon? Below we break down what works best for each application. Also, check out our complete Personal Locator Beacon Review to find out how each device scored in our tests and get more details on how SAT phone compare to SAT messengers.

Over the past few years, we don't know how many times we've heard someone say what a good idea it would be to "get a SPOT." Launched in 2007, the ad campaign for the original SPOT introduced many outdoor sports enthusiasts to the concept of emergency satellite messaging devices. Ten years later there remains a lack of understanding of how these tools work. When we began researching them for our own use, we were struck by the variety of options available and especially by how different each one of them is, even though they are widely viewed as all fitting into the same category of device.

To understand the options available, we first have to understand the satellite constellations and emergency support networks that support each device. Currently, there are three major systems:

1. COSPAS/SARSAT, non-profit network which supports PLBs (the ACR ResQLink in this review)
This satellite constellation is the largest and most complete, and is essentially military. It has provided the satellite support used for Emergency Position Indicating Radio Beacons (EPIRBs), which are designed exclusively for marine use, for more than 30 years. Over 33,000 people worldwide have been rescued as a result of this network since the program's inception. COSPAS/SARSAT now also supports PLBs, which are essentially EPIRBs for land-lubbers. It's essential to understand that a PLB is not a SPOT! This network covers the entire planet.

2. Globalstar, a for-profit communications network that supports the SPOT devices in this review:
The Globalstar corporation launched 52 satellites by 2000 to support a satellite phone communication network. It currently does not cover polar regions or sub-Saharan Africa (map:;
A series of problems with satellites from its first constellation launch was supposedly addressed in 2011 and 2012 with the launch of several additional satellites, but the total efficacy of their current network is still widely questioned.

3. Iridium, a for-profit communications network that supports the Garmin inReach devices in this review:
The Iridium network contains approximately 77 satellites that cover the entire planet, including polar regions. Its track record over the past 5-6 years has been less blemished than that of Globalstar's, but whether it still outperforms Globalstar is a matter of debate (For the record, the Iridium-supported device we tested worked more often than the Globalstar-supported devices).

Now that we have a basic understanding of the satellites, let's talk devices:
PLBs (ACR ResQLink)
A PLB does not require a paid annual subscription to send an SOS message. It transmits an SOS message with GPS coordinates via satellite, and in addition to that, emits a homing signal on the 121.5 MHz emergency frequency, at a power level 5 to 10 times higher than a SEND (SPOT or inReach) device. Furthermore, the PLB is much more likely than a SEND device to acquire the satellites necessary for a GPS coordinate lock.

A PLB emitting a distress signal in these two manners represents your best chance of being located and at this most basic level is a better device than anything operating on Globalstar or Iridium. That is to say when it comes down to the nitty-gritty and you press that SOS button, a transmitting PLB is far more likely to get you rescued than a SEND device. Don't forget this.

SEND (Satellite Emergency Notification Devices) (SPOT)
These devices require a paid annual or monthly subscription and transmit on a higher frequency (1610 MHz) to a commercial Rescue Coordination Center operated by Globalstar or Iridium. If you don't pay, you don't get rescued (It's interesting to note that even when you don't pay your mobile phone bill, you can still dial 911).

If all we cared about was getting rescued when we pressed the SOS button, we would not have written this review because choosing a PLB instead of a satellite messenger would be a no-brainer. But it's more complex than that, and the additional features available with the SAT messenger devices make them worth considering. For example, the Garmin devices not only give you a confirmation that your rescue is on the way, but they also let you communicate key details to help the rescue. You can't do that with the ACR or SPOT devices.

SEND devices transmit your GPS coordinate location only, and not all of the time. The SPOT 3 transmits its signal at one-tenth of the strength of the ResQLink, and there have been many documented cases of the SPOT 2 not transmitting an SOS successfully, and / or transmitting an SOS message without a GPS lock, which tells authorities and your contacts that you're in trouble, but not where you are. SEND devices do not emit the additional homing signal on 121.5 MHz. Also, the 5 watt 406 MHz PLB signal emitted by a PLB can be used by rescuers to establish an approximate location, whereas the SEND device's less powerful signal cannot be used in that way. If your SEND device can't get your GPS coordinates out due to line-of-sight obstructions, you'll wish that you'd bought a PLB instead.

In summary, in pure SOS terms, a PLB such as the ACR ResQLink is a far superior choice. The SEND devices offer some interesting and useful additional features, however, so read our complete Personal Locator Beacon Review to find out which device is best for you. There we break down the costs of each device as well as the alternatives such as SAT phones and SAT internet hubs.

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