Everglades Exploration Network

If you are like me and prefer to do your adventuring solo, then you will want to get one of these, especially if you are going deep into the wilderness. It probably doesn't hurt to have one even if you're with a group. I took one with me on my solo crossing of the Shark River Slough.

A personal locator beacon (PLB) operates on the 406 MHz satellite band and connects to the NOAA Search and Rescue Satellite Aided Tracking system (SARSAT). These are just like the EPIRB's that boaters use, but they are registered to a person, not a boat. If you should find yourself in a situation that you know you can't get out of without help, press the panic button to send a distress signal to SARSAT, and a rescue party will soon be on their way to your location. NEVER press that button if you aren't absolutely sure that you really require rescue!

The down side of a PLB is the price, running around $500-$600 for the high-end models that come with a subscription that is good for the life of the PLB. There are less expensive models that require that you renew your subscription yearly at additional cost. You can also rent one for about $60 a week, if you need one soon but can't afford to buy one. That's what I did for the Shark River Slough trip, but I intend to get my own dedicated PLB later this year.

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Hey Keith...and all.

Great topic and needs to be back on the radar for everyone.

So, I am shopping for a PLB and found this good discussion on REI...and you know what shopping for a PLB means?  Hammer time!  Heading out one last time before school...looking for another route between Big Cypress and Everglades WW

Anyway, here's the REI article:

PLBs and Satellite Messengers: How to Choose


While deeply rewarding, backcountry adventures also entail risks that can occasionally prove life threatening—even for the most experienced outdoor enthusiasts.

Technology has come to the rescue with:

  • Personal locator beacons (PLBs):Available in the U.S. since 2003, these satellite-based handheld devices provide a powerful safety net for wilderness travelers.
  • Satellite messengers: A more recent innovation, these handheld devices—such as those from SPOTand DeLorme—have evolved to offer additional backcountry communication options.

Though both are portable transmitters, personal locator beacons and satellite messengers have some important distinctions. This article covers the basics of each.

Shop REI's selection of personal locator beacons and satellite messengers.

Personal Locator Beacons

Personal locator beacons are high-powered (typically, 5 watts) devices designed primarily to send out a personalized emergency distress signal. They generally require an open view of the sky to transmit successfully.

PLBs are the land-based equivalents of Emergency Position Indicating Radio Beacons (EPIRBs), a technology that has been in use for decades in marine environments. Over the years, these devices are estimated to have saved more than 33,000 lives.

Important: A Personal Locator Beacon should be activated only in situations of grave and imminent danger, and only as a last resort when all means of self-rescue have been exhausted.

Shop REI's selection of personal locator beacons.

How a PLB Works

PLBs transmit powerful signals at 406 MHz (MegaHertz), an internationally recognized distress frequency monitored in the U.S. by NOAA (National Oceanic and Atmospheric Administration) and the AFRCC (Air Force Rescue Coordination Center).

A PLB communicates with a network of Russian, Canadian, American and French military satellites known as COSPAS-SARSAT (SARSAT is an acronym for "Search and Rescue Satellite Aided Tracking").

After receiving your transmission, these satellites "fix" on your location using a Doppler Shift method and relay your information to the AFRCC where search and rescue procedures begin. If you use a GPS-compatible PLB, you can deliver your GPS coordinates very quickly without having to wait for the satellites to determine your position.

Personalized Signal

PLB owners must register their device with NOAA. When you do so, NOAA will link your essential personal information to a 15-character code known as a Unique Identifying Number (UIN). When activated, the PLB transmits your UIN to the COSPAS-SARSAT satellites via electronic bursts.

While the electronic bursts provide search-and-rescue units with your location, the UIN tells them personal information such as your name, address, phone number and any medical conditions you may have.

Two Types of PLB Signals

When activated, a PLB sends 2 signals: 406 MHz (which carries the UIN and GPS data to the satellites) and 121.5 MHz, a homing frequency.

If you use a PLB without a GPS, the 406 MHz signal from the satellite will get rescuers to within 2 miles of your position. Then search-and-rescue teams will use a tracking device to home in on the 121.5 MHz frequency. With this type of PLB in the continental U.S., it takes an average of about 45 minutes to alert search-and-rescue teams of your position.

If you use a PLB with a GPS interface, the 406 MHz signal will guide rescuers to an area less than 100 meters from your position. At the same time, they will employ a tracking device to home in on the 121.5 MHz frequency put out by the PLB. When using a GPS-compatible PLB in the continental U.S, it takes only 5 minutes to alert search-and- rescue personnel of your position.

Note: REI carries only models with a GPS interface.

Keep in mind that it's always a good idea to have a visual and/or audible distress signal such as a signal mirror, whistle or strobe light to help catch search and rescue's attention when they get close. Many PLBs include a built-in LED signal light for this purpose.

How Long Will a PLB Transmit?

A PLB comes equipped with a long-lasting lithium battery. This battery remains dormant until you flip the switch to activate the PLB.

By COSPAS-SARSAT regulations:

  • A class 1 heavy-duty battery must be able to transmit at -40°F (-40°C) for 24 hours.
  • A class 2 battery must be able to transmit at -20°F (-28.9°C) for 24 hours.

Cold temperatures will shorten a battery's operating time, and the situations above represent worst-case scenarios. For example, at a temperature of 70°F, these batteries will operate for approximately twice as long as they will at very cold temperatures.

REI currently carries PLB models from ACR Electronics.

No Subscription Fees

Unlike with satellite messengers, you do not have to pay any recurring fees in order to use a PLB. Keep in mind, however, that rescues generally come with significant pricetags.

Satellite Messengers


Much like PLBs, satellite messengers are handheld transmitting devices that are useful in backcountry areas far from reliable cell phone coverage. These user-friendly devices allow you to communicate short text messages and/or your location coordinateswith friends or family back home so you can report on your trip’s status or, in an emergency, send calls for help.

While a handy tool for casual hikers and backpackers, satellite messengers transmit signals that are much less powerful than a PLB signal. They are not intended for serious mountaineering use.

How a Satellite Messenger Works

Satellite messengers are GPS-based devices that rely on either of 2 commercial satellite networks—Iridium or Globalstar—rather than the military network used by PLBs. Emergency calls using either network are routed to the privately run GEOS International Emergency Response Coordination Center headquartered near Houston, Texas.

A subscription fee is required to use a satellite messenger. Each manufacturer offers a variety of usage plan options, usually including duration (yearly, seasonally or monthly) and GPS tracking frequency (with intervals ranging from hours down to a few minutes).

What are the differences between the satellite networks?


  • Used by DeLorme devices.
  • Offers 100% planetary coverage via a 66-satellite network.
  • Uses 2 ground-based gateways (rather than satellites) process and switch messages.


  • Used by SPOT devices.
  • Covers most of Earth’s land masses (except polar regions and sub-Saharan Africa) via a 48-satellite network.
  • Uses 24 ground-based gateways to process and switch messages.

Note: Satellite messenger devices are considerably less powerful than PLBs and virtually always require an open view of the sky to transmit successfully.

Each satellite network has its share of fans and detractors relating to their ability to deliver messages 100% of the time. At this point, the jury is still out.


I use both a SPOT and PLB which in mandatory for WaterTribe events that I enter. 

The SPOT is solely used for tracking purpose so that my loved ones know where I’m at when out on camping trips.  It also has a SPOT Adventures webpage that I use to post some of my trips (http://www.findmespot.com/spotadventures/index.php/public_profile?profileid=73828 ).  I know that many SPOT users have reported dropped messages and worst case dropped Help messages.  This is why I will not rely on SPOT as a safety device. You have a onetime fee for the device plus a yearly subscription is $ 178.05 that includes optional tracking.

Have had my SPOT since 2011 with not issues.  I keep mine in a small clear waterproof bag with some dessicant packets.

I also carry an Ocean Signal PLB which is the smallest PLB on the market today.  When you registered with NOAA you get your own user account that you can change/update your info on.  This comes in handy when you don’t use the same vessel for all your trips.     This will be my go to device if sh*t hits the fan while in the Glades.  Anything can go wrong but a PLB brings peace of mind. 

SPOT currently has a 50% off deal.


Just looked at my EPIRB/PLB and realized that the battery expiration date has passed. NOAA requires new batteries every 5 years.

Went online to get the battery. Not so easy my friend...

Can't do it yourself, you have to send to to a service center. $160 +shipping both ways...

Probably cheaper to buy a new one!

So basically when you look at the price of a PLB, amortize it over a 5 year life!

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