At a Glance:
‣ PLBs and Satellite Messengers send emergency distress signals from remote locations.
‣ PLBs send one-way communication only, have no monthly cost and must be registered with a government agency.
‣ Satellite Messengers allow for two-way communication and require a subscription service (like a cell phone).
‣ Consider cost, battery life, and communication networks when choosing.
Going out into the woods often means leaving modern conveniences like your mobile phone behind. Even if you do bring it for taking photographs, you likely won’t have cell phone service. For many, this forced disconnection is a welcome respite until an emergency arises. In these unexpected moments, it is essential to have a personal locator beacon or a satellite messenger to signal for help. They can bring assistance when you need help getting out of the woods or can even save your life when you find yourself in a worst case scenario.
Personal Locator Beacons: send a one-way emergency distress signal.
Personal locator beacons (PLBs) send out a powerful one-way, one-time emergency distress signal that can be pinpointed to anywhere in the world. Once the signal is initiated, there is no turning back - help is coming whether you still need it or not. Consequently, they should only be used in life-and-death scenarios when self-rescue is not possible. There is no messaging feature with a PLB, and no subscriptions are required.
Satellite Messengers: a messaging device for remote two-way communication.
Similar to PLBs, satellite messengers send out an emergency distress signal that can alert authorities of your location. Not only can you request help, but you also can send text messages to search and rescue teams, so they know what gear they need to bring and how quickly they have to get to you. Beside emergency communication, satellite messengers also let you send messages to family and friends and have a tracking feature that allows others to follow your hike.
Personal Locator Beacon (left) versus Satellite Messenger (right)
Personal Locator Beacons
How Does a PLB Work?
A personal locator beacon has a single purpose - to alert authorities that you need help immediately. The distress signal on a PLB is designed to be easily activated by a person in distress or a bystander who finds an injured or unresponsive person.
Step 1: Activating a PLB. The device is activated by extending the antenna to its upright position and then pressing the emergency activation button that is only visible when the antenna is deployed. The antenna should be kept outside with a clear view and pointed to the sky, not buried in a backpack. Depending on the model, this process may also activate an LED strobe that makes it easy to spot someone at night. If you are not sure how to work a PLB, there are usually step-by-step instructions on the device.
Step 2: Distress Signal is Sent to a Satellite. When you activate a PLB, it sends out two signals - a powerful digital signal at 406 MHz that is received by the COSPAS-SARSAT international search and rescue satellite system and a low-power analog honing signal at 121.5MHz. If the PLB has GPS, then the 406 MHz distress signal will contain location coordinates that can be used to start a rescue effort as soon as the alert is received. If GPS is not available then the satellite will triangulate the location of the distress call and send along that information as soon as it is available.
Step 3: Distress Call is Received by Ground Center. Once the satellite receives the 406 MHz signal, it immediately sends it to a ground-based communications center that will alert either the AFRCC (Air Force Rescue Coordination Center) for inland rescues or the USCG (United States Coast Guard) for marine calls. These control centers then forward the details to the appropriate Rescue Coordination Center (RCC) in the US or a foreign SAR center if the call is international.
Step 4: Ground Center Relays Emergency to Local SAR. The RCC is responsible for initiating the search and rescue effort by contacting local authorities or SAR team(s). These alerts can be issued within minutes of receiving a signal, but it may take an hour or more to assemble a search team and coordinate a rescue mission. If weather conditions are favorable, search teams then hit the ground or the air to look for the origin of the distress signal using the transmitted location data and their knowledge of the area. They also can hone in on a victim using the 121.5 MHz signal that the PLB emits.
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What Is The UIN and How Does It Help?
PLBs not only send a distress signal and location but they also can send the Unique Identifying Number (UIN) of the device. Each device is linked to the owner's profile and provides search and rescue teams with relevant personal information such as a person's age, and known medical conditions. When you purchase a PLB, you are required by law to register the owner information in the NOAA SARSAT database. Registration is free here: www.beaconregistration.noaa.gov. Note owners need to renew their registration every two years or when they transfer ownership of the device
Can I Recall My Alert?
If the device is activated by accident, the alarm can be deactivated by pressing and holding the emergency button for five seconds. A false alarm must be reported immediately to the US Air Force Rescue Coordination Center (AFRCC) so the SAR alert can be canceled. Don't test the device by sending a false alert. Each device has a test mode that will communicate with the SARSAT satellite network without sending an alert.
2 Types of Signals: 406 and 121.5.
PLBs emit two distinct signals - a digital distress signal at 406MHz and a honing signal at 121.5 MHz. The 406Mhz transmission carries location data as well as the UIN of the device and initiates a Search and Rescue operation. The 121.5 MHz analog signal is used on the ground by search and rescue team members who carry or fly with equipment that can pinpoint the source of this low-power transmission.
Registration and Regulations: Class 1 vs. Class 2.
PLBs are sorted into two classes based upon their battery. Most consumer devices belong in the Class 2 category and have a battery that lasts 24 hours at -20°F (-28.9°C). A Class 1 PLB includes a heavy duty battery that can transmit for 24 hours at -40°F (-40°C).
Other Types of Beacons: PLB vs. EPIRB vs. ELT and differences
There are three major types of beacons -- a personal locator beacon (PLB), an Emergency Position Indicating Radio Beacon (EPIRB) and an Emergency Locator Transmitter (ELT). All three transmit a distress signal at 406 MegaHertz (MHz), but they differ in their intended usage and the type of data they send.
PLBs are the smallest of three, and their size makes them easier to carry than their EPIRB and ELT counterparts. They are meant to be carried by someone who is adventuring on land or near to the shore. EPIRBs are designed for maritime usage especially on vessels that travel more than 2 miles off the coast. They last up to 48 hours and are registered to the boat on which they are installed. ELTs are non-portable units meant to be fitted into an aircraft and are activated when a plane crashes.
How long will PLBs emit a signal? Is it reliable?
A PLB will emit a signal as long as the battery is operational. PLB batteries are dormant until activated and are required by law to transmit for a minimum of 24 hours. Most PLBs claim to deliver at least 30 hours of continuous SOS signalling.
Like most satellite devices, a PLB needs a clear view of the sky to operate. If you are in the thick woods or a deep cavern, you may have difficulty connecting to a satellite when sending a distress signal. The biggest drawback to a PLB is there is no way to confirm that the SOS was picked up by a satellite and that a rescue mission is underway.
What is a Satellite Messenger?
Satellite Messengers have the SOS feature of a PLB but add on tracking and two-way messaging for users who want to be connected while backcountry exploring. They are ideal for hikers and backpackers who travel to remote areas where there is no mobile phone coverage and want to stay in contact with friends and family at home.
(a map of SPOT's coverage)
How Does a Satellite Messenger Work?
Unlike the PLBs which use the government-backed SARSAT satellite network and SAR resources, the satellite messengers use a commercial satellite network (Iridium or Globalstar) and a private sector response center to handle emergency calls. Emergency calls with GPS data are sent to the satellite network and immediately routed to a 24/7 command center. The command center then contacts local SAR to initiate a search and rescue. Because they use commercial systems to provide SOS features and more, the satellite messengers require a monthly or yearly subscription on top of their purchase price.
The most significant difference between a PLB and a satellite messenger is messaging. PLBs only emit a distress call and cannot be used for communications. Satellite messenger,s on the other hand, can communicate with outside parties using the satellite system. Depending on the model and subscription plan, these messengers can send and receive messages with any mobile phone number or email address. Messages can be pre-configured with blurbs like "I'm OK" or custom texts that provide details about the current situation. The text can be entered directly on the device or through an app on a cellphone that is connected to the satellite messenger. This messaging feature is useful for communicating with loved ones and is indispensable during an emergency. Not only can you get a message confirming that your SOS has been received, but you also can provide details on your location and current situation to rescuers.
Tracking and Social Media.
Besides messaging, Satellite messengers also allow for tracking using GPS. Tracking points are sent via satellite to a website where they are displayed on a map. Family and friends at home can open this map and track a hiker's progress. Hikers also can share their location data on social media allowing fans to follow along with their adventure..
Satellite Messenger Subscription Requirements.
Because they provide a smorgasbord of features that use a commercial network, satellite messengers incur a monthly or annual fee above and beyond the initial purchase cost. These fees start at $11.95 a month for a small allotment of messages and climb upwards when you add in unlimited tracking and unlimited messaging. Each device must be registered and activated with a service provider to work, but there is no law requiring an owner to enter their personal information into a government database.
|ACR Aqualink||9.2 oz||$500|
|ACR ResQLink+||4.6 oz||$269|
|Garmin/DeLorme InReach||7.5 oz||$399-449|
|Garmin InReach Mini||3.5 oz||$349|
|Spot 3||4 oz||$169|
|Spot X||7 oz||$249|
Weight: 9.2 oz
The ACR Aqualink is designed for use on both land and water with built-in floatation and waterproofing for water accidents. This model has an LED display that makes it easy to use -- you can follow the on-screen instructions and receive information directly on the screen instead of trying to decipher beeps and LED flashes.
Weight: 4.6 oz
The ResQLink/ResQlink+ is ACR's entry-level PLB for consumers. The ResQLink and ResQLink+ are identical except the ResQLink+ is buoyant, while the ResQLink is not. Both models have all the SAR functions you need -- GPS, 406MHz and 121.5MHZ, but lack some of the extras like a dedicated LED screen. The sub $300 price point and small size are the device's main selling points.
Weight: 7.5 oz
Garmin bought out DeLorme a few years ago and acquired not only the company's robust map division but also one of the top satellite messengers on the market. Besides SOS, the InReach offers two-way messaging, tracking via a web interface, basic navigation (waypoints, routes), social media support and a mobile companion app. The mobile app lets you view your location on the map as well as send and receive messages. There are two InReach models -- the Explorer which ships with preloaded topo maps and sensors (barometric altimeter and compass) and the SE+ which lacks these additions.
Garmin InReach Mini
Weight: 3.5 oz
The Garmin InReach Mini is a pint-sized version of the InReach satellite messenger. The smaller unit weighs a mere 4.23 ounces and comfortably fits in a pocket. You lose maps and navigation, but you keep the messaging, SOS, GPS and mobile companion app of its bigger siblings.
Weight: 4 oz
Spot is the primary competitor to the InReach in the satellite messenger world. The Spot Gen 3 device is smaller than the InReach and less expensive, but it lacks the two-way messaging of its competitor. Spot Gen 3 only offers one-way messaging that allows a user to send a message and not receive one.
Weight: 7 oz
Introduced in 2018, the Spot X adds a keyboard and brings two-way messaging to the service. It also has a backlit display and can tie into your Twitter and Facebook account for social media updates.
Weight: 1.7 oz
GoTenna is a new category of backcountry communication devices that use MESH technology instead of satellites for their communication. Wireless MESH technology allows a small radio transmitter to connect with other transmitters in a 4-mile radius. These transmitters then link to other nearby transmitters creating a wide area network that can be used for group chatting, sharing a GPS location or even relaying an SOS message. These transmitters are small, but they are standalone devices. They require a smartphone to pair with to send and receive information. They also need a high volume of users to create a long distance network.