Category: Mobile

When Hurricane Irma closed in on the Tampa Bay area Sunday evening, the power went out at around 7:30, and soon afterward, cellular service became spotty and then disappeared entirely. However, we weren’t cut off from information about Irma because we fell back on a 1930s technology, FM radio, which is built into every smartphone, and accessible on many Android phones (including mine).

In the age of the smartphone, you might think your Android or iPhone can replace a radio receiver as a lifeline during a disaster. After all, while a radio receiver is audio-only and one-way, your smartphone can both send and receive text, audio, picture, video, and location information — but only if the cellular towers nearby are up and running. If the nearby tower is damaged, loses power, or gets overloaded, you’ll be cut off and left with the dreaded “No Service” indicator on your phone.

Consult just about any disaster preparation guide for a checklist of “must-haves”, and one of the items on that checklist will be a battery-powered radio. When phone and internet service fails, you can fall back on radio as long as you have batteries. (Better still, if you have a radio with a hand-crank generator, you don’t even need batteries.)

We have a nearly century-long tradition of radio stations providing vital information during disasters of all kinds. In the case of Irma, they did one better and teamed up with TV newsrooms. During the storm, many radio stations in the Tampa area teamed up with TV stations to provide continuous coverage of and information about the storm, such as where it was, how quickly and in which direction it was moving, and what to do. It was a valuable resource for many people, and it may have even saved a few lives.

You may think that you don’t own a portable FM radio, but chances are that you do. It’s just hidden away in your smartphone.

Just about every mobile phone maker — even the big ones who manufacture their own processor and graphics chips, such as Apple and Samsung — gets their cellular modem chipsets from a single manufacturer: Qualcomm. In fact, Qualcomm pretty much has a monopoly on these chipsets, which in addition to sending and receiving cellular signals, have an FM receiver baked in. You wouldn’t know it in the U.S., as fewer than half the smartphones have the FM receiver enabled, and they’re all Androids.

My Android phone is a Moto G4, and in addition to having an enabled FM receiver, it also comes “out of the box” with the FM Radio app, which simply provides a user interface for the FM radio capability. When the power went out in our part of Tampa on Sunday at around 7:30 p.m. and the cell service disappeared shortly after, I fired up the FM Radio app and we had updates on the storm’s progress all night long. In fact, I also used the phone’s FM radio and all day the next day — and there was still battery power to spare and the end. That’s because FM radio uses considerably less power than just about any smartphone function (and it uses no data at all!).

My iPhone doesn’t expose its FM radio capability, and it was useless as a source of updates until the cellular connectivity improved the next day, well after the storm had passed. I can’t say for certain, but I’ll just blame Apple designer Jony Ive, who’s never met a much-loved traditional feature that he didn’t like to remove. I get the feeling that FM radio is too distastefully old school to include as an iPhone capability, even though it’s already there.

While I experienced the usefulness of FM radio in smartphones during an emergency firsthand for the first time during Irma, it’s been clear to broadcasters and public safety officials — FEMA (the Federal Emergency Management Agency) included (see the video above) — that there are great benefits to unleashing this capability. The National Association of Broadcasters (NAB) has been lobbying to require the FM radio capability to be enabled in smartphones, and even Ajit Pai, chairman of the Federal Communications Commission (FCC) has been advocating for this (but he won’t go beyond advocacy). At an NAB event in February, he said:

“It seems odd that every day we hear about a new smartphone app that lets you do something innovative, yet these modern-day mobile miracles don’t enable a key function offered by a 1982 Sony Walkman.”

In Mexico, where there’s a strong radio culture (and a rise in non-commercial and community radio over the past decade), the Federal Telecommunications Institute (CIRT) approved a new rule in April requiring all smartphone manufacturers to enable the FM receiver. CIRT’s rationale was that in emergencies and disasters, having the FM capability would make it possible for people to get alerts and vital information when cellular networks failed. Mexico is the first country to pass such a law, and it’s hoped that other countries will follow suit.

Find out more

The go-to place for the movement to make the FM radio capability that’s already in our phones, waiting to be unleashed, is FreeRadioOnMyPhone.org. It has the latest info on the movement to enable FM radio on smartphones, including:

• How to get FM radio working on your Android phone
• How to contact Apple to ask them to enable FM radio listening on their phones
• How to contact the FCC and ask them to require FM radio be made available on phones
• The latest new about the movement

You may also find these articles of interest:

• Inside Radio: Emergencies Push FCC To Lobby For Smartphone FM
• Wired: Your phone has an FM chip. So why can’t you listen to the radio?
• NPR: The Hidden FM Radio Inside Your Pocket, And Why You Can’t Use It
• eMarketer: New Rules in Mexico Unlock FM Radio on Smartphones
• Recode: Trump’s FCC chief wants it to be easier to listen to free FM radio on your smartphone
• The Atlantic: Is that an FM radio in your pocket?

And finally, an article that needs to be pointed out because it’s dead wrong (and unsurprisingly, published by 2010-era Business Insider, from the time they were almost stealing content): Mandatory FM Radio: A Dumb Idea For Smart Phones, in which its clueless author says that it’s just a move to prop up the dying terrestrial radio industry.

This article also appears in The Adventures of Accordion Guy in the 21st Century.

One of the most common uses for smartphones is finding out where you are. According to a Pew report from September 2013, nearly three-quarters of adult smartphone users use their smartphones to get directions or other information based on their location.

At the heart of this functionality is GPS, the Global Positioning System, which is built into every smartphone and those tablets that are equipped to access cellular networks. Chances are that you’ve make some use of it, and we thought you might want to know how it works. In this article, we’ll explain GPS in layperson-friendly terms, and also give you some practical and not-so-practical tips on how to get the most out of it.

GPS constellations

The earth is surrounded by GPS satellites organized into a constellation. The basic design of the GPS system calls for a constellation divided into 6 different orbital planes, with 4 satellites per orbital plane, for a total of 24 satellites arranged the pattern shown below:

This arrangement ensures that no matter where you are on the planet, there will be at least four satellites in the sky above you.

We rely on the GPS system so much that there are more than 24 satellites in orbit; the additional ones provide additional accuracy and can be used as backup in case some satellites fail. At the time of this writing, there are 32 satellites in the GPS constellation, 31 of which are usable. You can find out how many GPS satellites are in the constellation at the moment by visiting the United States Naval Observatory’s Current GPS Constellation page and the constellation’s status with the Daily GPS Constellation Status page.

The GPS system is based on time and math you learned in grade school

The GPS system relies on time to measure distances. GPS satellites have onboard atomic clocks, which are the most accurate known time-keeping devices. Atomic clocks use the radiation emissions of a cesium isotope as a “pendulum” that “swings” about 9.2 billion times a second, providing nanosecond (billionth of a second, or 10^-9 seconds) accuracy. A nanosecond happens so quickly that during its span, even light can’t get very far: just a little over 9 feet (a little under 3 meters).

With such a precise clock, you can use radio transmissions to measure distances using the grade school math formula distance = speed × time:

With the distances between itself and a small number of GPS satellites, your smartphone can quickly figure out your location.

How your smartphone uses its distance from GPS satellites to figure out your location

We’re going to keep the explanations simple, and won’t bog you down with a lot of math. We’ll do this by treating space as having only two dimensions rather than three.

If you know the distance between yourself and a single satellite — let’s call it x — you know that you’re somewhere on a circle of radius x with the satellite in the middle. That narrows down your possible location somewhat, but it’s not enough to figure out where you are:

If you add another satellite to the mix and can get the distance between you and it — let’s call that distance y — you know that you’re also somewhere on a circle with a radius of y with that second satellite in the middle. Since you’re also on the circle of radius x, you must therefore be in one of the two places where both circles intersect. That narrows down the possibilities for your location considerably:

With a third satellite, you can perform trilateration, which narrows down your location to a single spot:

In case you were wondering, trilateration finds a location through the use of three distances. The term you’re probably more familiar with, triangulation, finds a location through the use of three angles.

Often, a fourth satellite is involved, and it serves two purposes:

• It’s needed to act as a reference for when the GPS signal arrived at your smartphone. Remember, in order to determine the distance between your smartphone and a satellite, you need to know the precise time when the signal arrived at your smartphone. Unfortunately, the clock on your smartphone isn’t anywhere as accurate as an atomic clock, so the GPS receiver in your smartphone uses the time broadcast from a fourth satellite as a reference clock to determine when the signals from the other three reached it.
• It increases location accuracy. Remember, in the diagrams above, we treated the earth as two-dimensional — that is, a flat surface — and required three distances to determine our location. In real three-dimensional space, we need four distances, which requires four satellites. However, with a little mathematical trickery that we won’t get into here, a GPS can get an approximate position with only three satellites.

Practical considerations

GPS alone doesn’t cost anything (unless you’re a U.S. taxpayer)

You may have noticed the cellular and internet networking aren’t mentioned in our explanation of how GPS works. Plain old GPS relies solely on the continuous, one-way signals broadcast by satellites and doesn’t need any cellular or internet data. Your smartphone doesn’t even send a request to a satellite to find its location, but simply listens to GPS’ always-on, always-available signals, in the same way you’d look for street signs and landmarks to get your bearings. As a result, using GPS by itself on your smartphone doesn’t eat into your data allotment or cost you any money…unless you’re a U.S. taxpayer.

The GPS system was developed by the United States Air Force, who’ve maintained it for the past 20 years and provide it for free to everyone worldwide. If you pay taxes in the U.S., you’re footing the bill for GPS, and lost people everywhere thank you.

Maps use your data plan unless you use offline maps

The location data that you get from GPS — your latitude and longitude — are meaningless by themselves to most people. Usually, this data is paired with contextual information, such as a map from Google Maps, or a database of nearby locations from apps like Yelp, Starbucks, or GasBuddy. This contextual information comes from the internet, and if you’re getting it through your cellular connection rather than wifi, it’s using your allotted data, and you’re paying for it.

If you use your smartphone as your navigation system and you’re driving long distances, your smartphone will download new map data as needed. If you’re on a limited plan, watch for this — this could be a big consumer of data.

If you use GPS often and are worried that your map use is eating into your data allotment, or if you’re using GPS while roaming, you should consider using offline maps. These are maps that are stored on your device, which means that it doesn’t have to use the internet to get them. As a result, you’re only using GPS to navigate, and not using any cellular data. Here are a couple of offline map options:

• The Google Maps app (free, available on the iOS App Store and Google Play) allows you to download and save maps for areas as large as 31 miles by 31 miles (50 km by 50 km). Here are the iOS instructions, and here are the Android instructions.
• MAPS.ME (free for the “lite” version) runs on iOS, Android, and BlackBerry. There’s a “lite” version that provides the basics for getting around, and a paid “pro” version that lets you search and bookmark locations.
• Galileo (free, available on the iOS App Store) is a good choice for iPhone and iPad users looking for a free offline map app.
• If you want a more full-featured map app, you should consider looking at paid apps. Wired recently reviewed a few of them: Sygic, Navmii, CoPilot, and Navigon.

GPS works better with cellular and wifi networking turned on

Since GPS uses radio waves from satellites to measure distances, it works best when the straight-line path between your device and the satellite isn’t impeded. Getting clear line-of-sight to the satellites above isn’t always possible in urban or tree-lined areas, and it’s impossible when you’re indoors. Luckily, there’s WPS (Wifi Positioning System), which is used to augment GPS by making use of the known locations of wifi base stations.

WPS works by using one or more databases containing the locations of wifi base stations based on their “fingerprints”, which are based on their SSIDs (their “names”) and MAC addresses (the unique identifier attached to every networked device) and their signal strength. These databases contain information on up to hundreds of millions of wifi base stations gathered from various sources. Quite often, these sources are everyone’s smartphones, which continually scan for wifi base stations and transmit their “fingerprints” and locations back to Apple, Google, or Microsoft, depending on your phone’s operating system. The keepers of these databases assure us that they’re protecting our privacy by anonymizing the data (take this statement with an appropriately-sized grain of salt).

There’s also aGPS — assisted GPS — which uses cellular networking to help your smartphone get the necessary information to more quickly acquire the satellite signals.

If you turn on cellular and wifi networking  on your phone, it works in combination with GPS to provide you more accurate location information in more places, even in places where satellite signals aren’t as accessible. Wifi-only devices, such iPads without cellular data capability, use WPS to determine their location.

GPS is a power hog

Listening for an extended time to a handful of radio signals from satellites in space transmitting at a very slow rate — 50 bits (three characters on a web page) per second — eats battery power. Since your smartphone has to listen for these signals for extended periods, using GPS causes it to override its very clever and aggressive power-management system, which normally keeps power consumption to a minimum. Mapping applications, which are often used in conjunction with GPS, are processor-intensive, which increases the power drain.

When you’re using GPS on your phone while unplugged, use it sparingly. If you’re using GPS on your phone on a long drive, plug it in. You should keep a spare USB charging cable in your car, and if it doesn’t have a USB charging port, you should also keep a cigarette lighter USB power adapter (pictured above and to the right) handy.

Not-so-practical (but fun) considerations

On newer smartphones and operating systems, GPS stays on even in airplane mode

If you’re using iOS 8.3 or later (you can check by going to Settings → General → About and then look for Version) or a number of newer Android phones (including Samsung Galaxy S4 or later), the GPS remains on even in “Airplane Mode”.

This is probably due to the fact that GPS is a receive-only technology; it doesn’t send out signals and therefore is less likely to interfere with the airplane’s electronics and navigation systems. Now that a number of flights have wifi, it’s now possible to see a map showing your current location in mid-flight. If you zoom in closely enough, you can see how quickly you’re zipping over city streets, which is an oddly mesmerizing experience.

GPS, Interstellar, and Einstein can turn you into a science genius

And finally, here’s an interesting fact concerning GPS that will give you some serious science cred at your social gathering. Let’s take a little detour by way of this scene from the 2014 film Interstellar:

In the scene pictured above, a team of astronauts led by Matthew McConaughey lands on a water-covered planet orbiting giant black hole. The black hole’s gravity is so strong that it slows down time in its general vicinity: for every hour they spend on the planet, seven years pass for outside observers.

The idea of gravity slowing down time wasn’t something dreamed up by the film’s authors. Instead, it was dreamed up by Albert Einstein, when he came up with the Theory of Relativity. We’ll simply summarize Einstein’s greatest work with these two practical consequences:

While the effects of gravity on the GPS system aren’t anywhere as dramatic as in Interstellar, they’re still important enough to be accounted for.

GPS satellites orbit the earth at an altitude of 12,500 miles (20,000 km), which means that the force of gravity on them is much lower. While in orbit, they move at 8,700 mph (14,000 km/h). Both these factors have measurable effects on time:

Since the GPS system relies on precise timekeeping, it introduces a time correction to account for the different speeds at which time moves on earth and on the satellites. The fact that this correction is needed is a practical, everyday application of Einstein’s Theory of Relativity and the seemingly sci-fi concept of warping time.