Articles (2020)

Introduction

After too much Type 2 and Type 3 fun, my wife wanted me to be able to call 911, and to stay in touch with her when in the backcountry. I had sent satellite phones with scientists to worldwide locations for more than 10 years, and new devices like the SPOT Satellite GPS Messenger had just reached the market. So I did some market research to fill my needs. At one point, my wife said something like “maybe other people would want this information.” Little did I know how much work lay ahead.

This article is the first in a three part series on two-way satellite communications for lightweight backpacking. This Part 1 is an introduction; briefly describing alternatives, how satellite systems work, and each of the satellite systems you might consider. Part 2 covers satellite phones, and Part 3 covers satellite text-only devices. All the information in this series comes from vendor web sites and online reviews, except for the “Personal experience” sections.

Why?

Why might you want two-way satellite communications while backpacking? Ignoring serious concerns about self-sufficiency and disconnecting from the grid, the most common reasons seem to be:

• You want to get help in an emergency.
• You want to communicate with loved ones; that might be a condition of your trip.
• You want to communicate with work; again, that might be a condition of your trip.
• You want to make re-supply changes from the backcountry, including ordering new or replacement equipment.
• You want near real-time tracking of your position.
• You want Internet access and can accept significant weight or speed penalties.

Two-way communications with first responders, family, or friends can mean the difference between life and death, between Type 2 fun and an unnecessary rescue, between saving your own life and unnecessarily risking the lives of rescuers.

The August 2011 Outside magazine article Panic Button describes the search and rescue problems with one-way devices like PLBs and SPOT.

Let’s briefly review other technologies you might use for wilderness communications.

Cell phones

Many wilderness areas have little or no cell phone coverage, especially where you are furthest away from civilization. You might want to take a smart phone anyway, see Part 3.

BGAN satellite terminals

You may have seen TV journalists sending videos from war zones using portable Broadband Global Area Network (BGAN) satellite terminals. The lightest terminals weigh 1-2 kg and cost over $1,000 new, or you can rent one. You must add a phone to make phone calls, and a laptop, tablet, or smart phone for Internet access. Look into these if you really need medium speed Internet access from the backcountry – “up to” 492 kbps – and you are willing to carry the extra weight.

Ham radios

Ham radios can be light and cheap, with no service charges, but you must pass an exam to get a special license to use one. The range of small, light ham radios can be very limited. You may not use ham radios for commercial purposes.

PLBs

Personal Locator Beacons (PLBs) are good for one thing only: rescue in case of dire emergency. On the other hand, PLBs are relatively light, have no monthly cost, you can’t call home or work, and they can’t call you. Recent PLBs send an emergency signal with GPS coordinates through government-operated satellites, and a homing signal to guide rescuers locally. PLBs should be registered periodically with your contact information, to reduce false alarms. Registration is free in USA. Though sometimes used interchangeably, a PLB is different from an EPIRB, and backpackers should not use an EPIRB.

One-way texting by satellite

Several devices can be used to send one-way text messages, track your trip, and notify emergency services, including your GPS position. One-way devices are often lighter and cheaper than two-way devices.

Many one-way devices can send only three or four pre-defined messages – no good for “send more Pop-Tarts” unless you anticipated that message. And one-way devices cannot provide feedback, like “Stay put, we can’t rescue you until the storm clears”, or “Are you sure you want forty cases of Pop-Tarts delivered to Idyllwild?”

SENDs versus PLBs

Generically, one-way and two-way satellite texting devices can be Satellite Emergency Notification Devices (SENDs), similar to PLBs. PLBs use government satellites, have no recurring fees in USA, and send emergency notices directly to rescue authorities, while SENDs use commercial satellites, with recurring fees, and send emergency notices through commercial monitoring services first.

 Carrier Pigeons

Carrier pigeons can be used for communication up to 1,600 km. Pigeons weigh 300 g to 450 g, and need about 50 g per day of feed, plus a cage. You can use a pigeon just once per backpacking trip, making them impractical for lightweight backpacking. Some commercial photographers routinely send 256 GB SD cards with photos and videos by carrier pigeon. A carrier pigeon with a 4 GB memory stick was faster than DSL in a 2009 race in South Africa. For return messages, you must train another set of pigeons to fly to pre-arranged spots along your trip. You can access the Internet over carrier pigeons, using well-defined standards (see RFCs 1149, 2549, and 6214), but you will have problems with high latency, and high packet loss due to hawks and other raptors. I don’t recommend Skyping over this connection.

How two-way satellite systems work

Satellite signals must travel in a direct path between your device and a satellite, and between a satellite and a ground station, which is connected to the phone system and the Internet. Satellite signals are even weaker than cell phone signals, blocked by buildings, mountains, canyon walls, trees, and sometimes, heavy rain or snow.

Satellites are expensive: Globalstar, Iridium, and Orbcomm lost many satellites due to launch failures or other problems; the original Iridium system cost an estimated $6 billion; and Globalstar, Iridium, Orbcomm, and Terrestar have gone through bankruptcy. With cell phones covering over 90% of the world’s population, the satellite system market is small. Satellite devices and plans are much more expensive than cell phones, and generally have far fewer features.

Two-way satellite systems have three basic designs:

• Bent pipe
• Space network
• Store and forward

A “bent pipe” satellite immediately retransmits your phone call, text message, or Internet connection, back to a ground station within sight of the satellite. These satellites are relatively simple. Globalstar, Inmarsat, Terrestar, and Thuraya are “bent pipe” systems.

A “space network” system can relay your phone call, text message, and Internet connection between satellites until a ground station is in view. These satellites are much more complex than “bent pipe” satellites, but require fewer ground stations for global coverage. Iridium is the only “space network” system.

In a “store and forward” system, the satellite receives and stores your text message until a ground station is in view, then forwards your message. Messages are delayed for 1 to 100 min each way. You cannot make phone calls or use the Internet over these systems. Orbcomm is a hybrid “bent pipe” and “store and forward” system.

Voice quality and Internet access

The voice quality of most satellite systems is good to just acceptable. Some systems are consistently better than others, though all vary depending on many factors.

Have you ever used dial-up Internet access? That was blazing fast compared to satellite Internet access for lightweight backpackers. You should be rich, extremely patient, and use special setups designed for low speeds and interrupted sessions.

Geostationary Satellites

Commercial communication satellites are placed into two very different kinds of orbits around the Earth: Geostationary orbits (GEO), 35,786 km above the equator, and low earth orbits (LEO), at fixed heights from 772 km to 1,400 km high. If the Earth were the size of an NBA basketball, LEO satellites would be about 4-8 cm away, and GEO satellites would be about 2 m away.

A GEO satellite appears to hover at a fixed position over the equator, more-or-less in the southern sky as viewed from the northern hemisphere. Three GEO satellites can provide virtually worldwide coverage. Each satellite needs just one ground station to connect to the phone system and to the Internet. GEO satellites need large antennas, powerful transmitters, and large solar panels, and they are designed to operate for up to 20 yrs. Satellite TV (e.g. DirecTV, Dish Network), weather forecasting, and missile warning systems use GEO satellites.

What are some of the downsides of GEO satellites?

• If a mountain or forest blocks that spot in the sky, you can’t contact the satellite. You must move to a better position, which might be difficult depending on terrain and injuries.
• As you go further north or south of the equator, the satellite appears lower in the sky and is blocked more easily. In Alaska, the satellite might be barely above the true horizon. GEO satellites are unusable above latitude 70 (Arctic and Antarctic areas).
• GEO satellites are so far away, that the speed of light causes annoying pauses during phone calls.

Low Earth Orbit Satellites

You need 44 to 66 LEO satellites, plus spares, to provide full-time coverage worldwide. LEO satellites are launched into many different orbits 772 km to 1,400 km high, crisscrossing the sky. Each satellite circles the Earth in about 100 min. Any satellite is visible 9 min at a time on average, even less with local obstructions, so longer connections require hand-offs from one satellite to another. “Bent pipe” systems using LEO satellites require dozens of ground stations to provide nearly worldwide coverage – your device must be within about 5,000 km of a ground station. “Space network” and “store and forward” systems can use just one ground station, but usually have several. LEO satellites have smaller antennas, lower power transmitters, and smaller solar panels than GEO satellites. LEO satellites don’t last long due to atmospheric drag – sometimes less than 10 yrs. The International Space Station, Hubble Space Telescope, and Google Earth photo satellites are in LEO orbits.

What are some of the downsides of LEO satellites?

• You need an unobstructed view of most of the sky to contact a satellite, and to keep the connection running for more than a few minutes.
• A LEO system with missing or malfunctioning satellites suffers from constantly shifting coverage gaps, with much higher rates of dropped calls or missed messages.

Theoretical coverage versus Service

Theoretically, each satellite system can cover the entire Earth, or a major portion of the Earth. In practice, satellite systems restrict coverage for technical, economic, or legal reasons. Most satellites use “spot beams” to focus power on limited areas, and they can determine your position close enough to allow or deny service as desired. Iridium and Globalstar do not work in several countries for legal reasons. Terrestar could cover most of North and South America, but limits coverage to most of the United States. Be sure to check the latest coverage maps and local laws before you choose a device, or take a device into a new area.

Factors affecting signal strength

A weak satellite signal will degrade phone call voice quality, reduce data speeds, or stop connections entirely. Some of the factors that affect signal strength are:

• Obstructions: Satellite signals can’t go around or through obstacles like mountains, canyon walls, trees, and buildings. You should be OK inside a tent or under a tarp – but if you are having trouble, move outside. Human bodies are very good at blocking most satellite signals; satellite phone antennas should be above your head, and tracking devices should be placed on top of your pack.
• Operating frequency: Lower frequency signals penetrate leaves and branches better, but require larger antennas. Most systems operate at 1.5 GHz to 2.5 GHz, except Orbcomm at 137 MHz to 150 MHz.
• Distance: GEO satellites are much farther away than LEO satellites. A LEO satellite near the horizon is about 2,500 km farther away than one directly overhead.
• Elevation above horizon: If a satellite is low on the horizon, the signal must punch through about 10 times more atmosphere. LEO satellites can be low on the horizon for one pass, high overhead on the next.
• Satellite speed: Satellites zipping by in LEO orbits require more power and special processing at both ends to compensate for the Doppler effect. All satellite systems have this problem if you are moving faster than hiking speeds. Some devices won’t work well in a car at highway speeds.
• Effective satellite power: Effective power is a combination of satellite signal power and satellite antenna design. Most satellites use spot beams that concentrate power on a smaller patch of Earth.
• Device power: Most handheld devices transmit about 1 watt of radio power (not much) – to a satellite 772 to 40,479 km away. Battery life, health-and-safety regulations, and other regulations, limit device power.
• Device antenna design: Bigger antennas generally provide a stronger signal, but big antennas are not practical for handheld devices.
• Device antenna orientation: All devices show dramatic changes in signal strength and quality with small changes in antenna orientation. Sometimes a step or two, or a slight twist, makes all the difference – we see that with cell phones, too. Most antennas are designed to point straight into the sky; some don’t work at all if horizontal.

You can avoid obstructions and orient your antenna correctly; all the other factors are determined by your device, satellite system, time, and location.

Devices locked to one system

Satellite phones and text-only devices are locked to one satellite system by patents, technology, and physics. For example, you cannot switch an Iridium phone to call using Globalstar satellites. When you buy a device, you are locked into one system, with very limited choices on plans and prices. Choose wisely.

Satellite Systems

Globalstar

Globalstar covers most of the world with phone, text, and low-speed Internet services, using 48 “bent pipe” satellites in LEO orbits 1,400 km high. Several phones use Globalstar, but Globalstar is better known for providing service to SPOT devices.

Some Globalstar satellites have problems affecting phone calls, two-way text, and Internet services, resulting in spotty coverage and dropped connections. Globalstar provides a web site that predicts coverage times for any location. You should prepare tables of locations and times just before heading into the backcountry; predictions go out only 3-4 days.

Predictions for my home town from calltimes.globalstar.com over a 3.75 day period in January 2013 showed 148 interruptions, 84% time coverage, 1 min to 107 min coverage windows, and 30 min average coverage window.

In February 2013, Globalstar launched the last six replacement satellites needed to fix these problems. Globalstar expects to put these satellites into service by summer of 2013. Check www.globalstar.com for the latest news.

One-way messages from SPOT devices are not affected by these problems.

 

Inmarsat

Inmarsat covers most of the world between latitudes 70 S and 70 N, with phone, text, and Internet services, using three “bent pipe” satellites in GEO orbits. Inmarsat works with just one handheld satellite phone – the IsatPhone Pro. Inmarsat does not support any text-only devices. Inmarsat also supports BGAN terminals.

 

Iridium

Iridium covers virtually the entire world, with phone, text, and Internet services, using 66 “space network” satellites in LEO orbits 780 km high. Iridium works with several handheld satellite phones and text-only devices. The US Department of Defense is a major user of Iridium, owning and operating their own ground station in Hawaii. Iridium is prohibited by US laws from operating in Taliban controlled Afghanistan, Cuba, Iran, North Korea, Syria and Sudan.

Orbcomm

Orbcomm covers selected areas of the world for short message service only, primarily for tracking trucks, ships, and shipping containers. Orbcomm has 29 hybrid “bent pipe” and “store and forward” satellites in LEO orbits 774 km high; 29 satellites are not enough for full-time coverage. Recent Orbcomm devices switch between satellite service and cell phone service automatically. No currently manufactured Orbcomm devices are suitable for lightweight backpacking, though the Magellan GSC-100 was an interesting early device still available on the used market (see Part 3).

Terrestar

Terrestar covers most of USA except parts of Alaska, with phone, text, and Internet services, using one “bent pipe” satellite in GEO orbit. Terrestar works with just one satellite phone – the Terrestar Genus. Terrestar does not support any text-only devices. Terrestar service is supplied by a combination of DISH Network and AT&T, so you can switch a Terrestar Genus phone between satellite service and AT&T cell phone service.

Thuraya

Thuraya covers Europe, most of Asia, most of Africa, and Australia with phone, text, and Internet services, using two “bent pipe” satellites in GEO orbits. Thuraya has a variety of small, light phones, and good airtime prices – useful if you are traveling in their coverage area. Thuraya also supports a BGAN-like satellite terminal.

Important Satellite System Features

1. Globalstar phones can receive 35-character text messages, but not send them. SPOT devices can send text messages, but not receive them.
2. Orbcomm satellites “store and forward” short 200-character messages, and use “bent pipe” for longer 2000-character messages.
3. I cannot find Terrestar Internet speed on any official Terrestar web site, including terrestar.com, dish.com, att.com or amazon.com. Unconfirmed reports list speeds as either 64 kbps, or 160 kbps down, 30 kbps up.

Recommended systems for satellite phone or text

The performance of any satellite system is strongly dependent on the devices you use, how you use them, and where you use them. Reviews really compare devices and use cases, not systems. Still, we can compare satellite systems based on design, operations, and available devices.

So in my not-so-humble opinion …

Best: Iridium

• Iridium’s “space network” design and continuous, nearly global coverage, is more comprehensive and reliable than all other systems.

OK: Inmarsat, Terrestar

• Inmarsat and Terrestar use GEO satellites, so you must have an unobstructed view of specific satellite locations to use them. Inmarsat provides coverage over most of the Earth; Terrestar is limited to most of USA, but you can switch between satellite and AT&T cell phone systems.

Marginal: Globalstar

• Until Globalstar replaces all their malfunctioning satellites, phone coverage is intermittent and difficult to predict in the backcountry. One-way messages from SPOT devices are not affected by these problems. Globalstar could rate “OK” after satellite replacement scheduled for summer 2013.

Non-players: Orbcomm, Thuraya

• Thuraya doesn’t cover USA (rates “OK” in coverage area), and Orbcomm doesn’t support any devices suitable for lightweight backpacking.

Recommendations for satellite Internet access

OK: Terrestar

• Terrestar might have the fastest handheld satellite Internet access in USA – only in USA and if you can see the satellite. If you have AT&T cell coverage, you have 3G Internet access speeds, too.

Marginal: Inmarsat, Iridium

• You can access the Internet at very low speed over an Inmarsat or Iridium phone. Don’t try to do it yourself with a direct connection. Get an Iridium AxcessPoint Wi-Fi hotspot, or a Humanedgetech.com expedition package. See Part 2 for details.

Alternative: BGAN terminal with Wi-Fi Internet device

• BGAN terminals provide medium-speed Internet access, but weigh 1-2 kg plus Internet access device. Some BGAN terminals include Wi-Fi, and will work with most smart phones, tablets, and laptops.

Not recommended: Globalstar

• Until Globalstar replaces all their malfunctioning satellites, Internet connections are intermittent and subject to unexpected drops. After satellite replacement scheduled for summer 2013, Globalstar could rise to “Marginal.”

Non-players: Orbcomm, Thuraya

• Thuraya doesn’t cover USA (rates “OK” in coverage area), and Orbcomm doesn’t support Internet access.

Next up – Part 2: Satellite Phones for Backpacking

About the author

Rex Sanders has been backpacking off and on since the 1960s, and guiding whitewater rafts since 1987. In his day job, he supplied globetrotting scientists with Globalstar and Iridium phones from 2000-2011. But he never got to go on those adventures. He does not own any of these devices, and does not have any relationship with the companies mentioned here.