Oh Brother, Where Art Thou?

So you think you know where you are? And how did you deduce that seemingly trivial fact, I wonder?

Yes, dear reader, determining your location is no longer an arduous task. But you should quickly remember that for the average Joe or Jolie it’s only been that way for a very short while.

It took the pervasive proliferation of those pocket computers we now all carry around to make it so.

But only by 2016 did global penetration of smartphones cross 50%¹, so you could argue that it’s only been 8 years since the majority of people on this planet have been able to quickly determine their location.

That’s actually a pretty astounding fact.

Yeah, yeah — I know — there was a way to quickly determine your location prior to the dawn of iPhone. You could use your favorite personal navigation device (PND). But that only helped if you were in your car. And global penetration of PNDs never got a smidgeon close to smartphones.

This innate ability to determine your location can take so much stress out of you life. No longer do you have to roll down the window of your car in shame and, most of the time at least, no longer do you have to be so stressed about getting lost when you’re on a leisurely country walk.

For those of you that don’t remember, this is what it used to be like [click to play]:

Yup, that fear of being maced and tasered has receded somewhat.

However, I should also offer the rebuttal to say that easy location determination has substantially increased our stress levels: it’s made possible by all those slimy apps that track your every move. See Map Happenings post: “Location Harvesters, Personal Information Brokers & Assholes“.

Moving on.

What effect has all this easy location determination had on our world? The list is of course somewhat substantial:

• Real-time navigation — by car, by train, by bicycle or on foot
• An explosion of tracking apps for vehicles, shipments, rides, deliveries, aircraft, boats — and let’s not forget tracking birds and animals
• A complete revolution for search & rescue
• A complete revolution for surveying & construction
• Enabling a geo-index of nearly everything (photos anyone?)
• The foundation for self-guided machines — tractors and bulldozers, drones and perhaps one day: cars & trucks

So, it’s pretty easy to make the case that this phenomenon should win a spot on the list of “12 Map Happenings That Rocked Our World”. But how did it all come about? And what remains to be done?

If you’re so inclined I’ll take you though the story of how we got to where we are… and a little bit of where we’re headed. It ain’t all down to GPS.

Determining Your Location: First Things First

A couple of things had to happen:

• Someone had to invent maps (see “12 Map Happenings That Rocked Our World: Part 1: The First Map“)
• Someone had to invent a coordinate system (see”12 Map Happenings That Rocked Our World: Part 2: The Birth of Coordinates“)

Then someone had to invent how to determine your location. Figuring out your latitude (how far north or south you are) was a relative breeze. But by comparison, determining your longitude (how far east or west you are) turned out to be a real stinker of a bitch.

The story of how this problem was solved is an epic tale. TL;DR: the problem was solved by an uneducated carpenter from the north of England in the year 1759. It was all about clocks.

If you’d like to delve deeper may I suggest three options:

• Option 1: if you have 15 minutes: read “12 Map Happenings That Rocked Our World: Part 4: The Epic Quest for Longitude“
• Option 2: for the full story: read Dava Sobel‘s amazing and best-selling book ‘Longitude‘.
• Option 3: if you’re like certain politicians and have difficulty reading: watch the PBS video “Lost at Sea” narrated by Richard Dreyfuss. Actually — even if you can read — watch the video anyway. It’s such a cool story.

Precursors to GPS: Acoustic Locators, Gee & LORAN

Acoustic locators came first. They were used in World War I to determine the location of enemy artillery. The system employed microphones to measure the direction that artillery fire was coming from. With the use of two or more microphones at different known locations it was possible to determine the location of artillery using simple trigonometry.

But these weren’t like your average Shure microphones you use for podcasting. Take a look at this one from 1927:

Or these Japanese ones from before World War II:

Next up: Gee.

Gee, not to be confused with the clarified butter you might find in an Indian deli, was a radio navigation system invented by the Brits during World War II. By measuring the time delay from radio signals emanating from multiple known locations it was possible to measure position using a method called hyperbolic navigation. Gee’s main purpose was to allow bombers returning from a night bombing raid find their landing strips, thereby providing a blind landing system.

The methodology was a follows:

Two transmitting antennas positioned about 10 miles (16 km) apart on either side of a runway. A transmitter midway between the two antennas would send a common signal over transmission lines to the two antennas, which ensured that both antennas would broadcast the signal at the same instant.

A receiver in the aircraft would tune in these signals and send them to an [oscilloscope]-type display… If the aircraft were properly lined up with the runway, both signals would be received at the same instant, and thus be drawn at the same point on the display. If the aircraft were located to one side or the other, one of the signals would be received before the other, forming two distinct peaks on the display. By determining which signal was being received first, pilots would know that they were closer to that antenna, and would be able to recapture the proper direction by turning away from it.

The guy that invented Gee, one Robert Dippy, later went on to help the Americans develop a longer range version, called LORAN — short for LOng RAnge Navigation.

How did LORAN Work? Well here’s a short 2 minute video courtesy of the Smithsonian Institution:

LORAN evolved over the years. It first went live in June 1942 and was declared operational in early 1943. The original system begat LORAN-B (which was a failure), but that begat LORAN-C. The US LORAN-C transmitters became operational in 1958 and were managed by the US Coast Guard. The original LORAN-A systems remained operational until about 1985. LORAN-C was opened to civilian use in 1974 and the US transmitters were finally shut down on 8 February 2010.

Has it all been replaced by GPS? Well as a matter of fact just like vinyl records, it is getting a revival. With the potential vulnerability of today’s satellite positioning systems due to GPS interference a new version of LORAN is being explored and selectively deployed. Called Enhanced LORAN or ‘eLORAN’ it is under consideration by a number of nations. Other countries continue to operate LORAN transmitters around the world.

GPS and its Catalyst

I think pretty much everyone has at least heard the term ‘GPS’. It of course stands for Global Positioning System. And, surprise, surprise, it has its origins in the US military. The GPS system is owned by the US government and is now operated by the US Space Force.

The catalyst for developing GPS all started after the USSR launched the first man made satellite, Sputnik 1, way back on 4 October 1957. Within hours of its launch two enterprising chaps, William Guier and George Weiffenbach, who were physicists at the Johns Hopkins Applied Physics Laboratory (APL) realized they could determine the satellite’s position by monitoring the radio signals and measuring the changes in frequency of the signals at known locations on the earth due to the doppler effect.

It wasn’t long before the laboratory’s deputy director, Frank McClure, asked them to invert the problem: could they pinpoint a user’s location given a known position of the satellite’s?

And why was this so interesting? Well it all comes down to the fact that the US needed more effective ways to blow up the planet and one of them was by putting nuclear warheads on submarines. But a missile fired from a submarine couldn’t turn Moscow into a blob of molten glass unless you knew the exact position of the submarine relative to Moscow, preferably within a few hundred feet.

It turns out we can pinpoint the exact date on which the whole idea for satellite navigation was birthed. Guier and Weiffenbach’s recount the story in their 1998 paper:

From here on, we were in for the adventure of our lives. On Monday, 17 March 1958, Frank McClure called us to his office and asked us to close the door. He asked us if anything new suggested that we had exaggerated our claim that we could find an approximate orbit from a single pass of Doppler data. When we replied that nothing had really changed, “Mac” asked if we could invert the solution, i.e., determine the station position while assuming the orbit is known.

This all led to the development of something called the Transit Navigation System. The first attempt to launch a prototype satellite for Transit was in September 1959 and the whole thing became fully operational in 1964. It was used primarily by the US Navy to provide accurate location to its fleet of Polaris ballistic missile submarines. Transit had a long history and didn’t cease its navigation service until 1996 by which time it was made obsolete by GPS.

If you want to dig deeper into the technical methodology behind Transit then I’d suggest reading Wikipedia’s page.

What of GPS?

Although groundbreaking the Transit system was deemed too slow and too intermittent to keep up with the speed of airplanes. A more accurate and reliable system was needed.

Fortunately Transit was not alone and in the 1950s and 60s several other systems were developed in parallel. All of them had one goal in mind: getting an accurate fix of land or sea based missile launchers before they launched nuclear armageddon. These other systems included:

• MOSAIC (1950-61): ‘MOSCAIC’ was developed by the Missile Division of Raytheon and stood for “MObile System for Accurate ICBM Control” It was essentially a 3D LORAN.
• Project 621B (1963-73): Developed by the Aerospace Corporation (1960-present) this proof of concept project had over 1400 scientists and engineers on staff. Aerospace had been commissioned by the US Air Force to continue work on determining navigation coordinates from satellite signals and in particular meeting an accuracy requirement of 15 meters. Through its fundamental research Project 621B laid many of the foundations for GPS. By the late 1960s Aerospace recommended a design that used 20 satellites placed in geosynchronous orbit.
• The Timation Satellites (1964-74): these proved the feasibility of orbiting accurate clocks in space, a necessary requirement for GPS. In essence this was a 20th century version of John Harrison’s H4 chronometer from 1759 (see “12 Map Happenings That Rocked Our World: Part 4: The Epic Quest for Longitude“). The pièce de résistance was the July 1974 launch of the third Timation satellite which was the first to fly an atomic clock.

By the late 1960s it was clear that a solution to meet all the requirements was going to need a boat load of coordination and a boat load of money. So in 1968 the US Army, Navy and Air Force combined forces to form NAVSEG (Navigation Satellite Executive Group).

Alas, the group had no power to enforce any decisions it made. So in 1969 the president of Aerospace, Ivan Getting, asked president Nixon’s science advisor for help. Rather than advocating for a presidential commission the advice was to continue to push the ideas through the military customers. It turned out to be an astute move.

The main customer ended up being a chap called Air Force Colonel Bradford Parkinson. Put in charge of Project 621B in 1972 he concluded that some elements of Project 621B, Timation and Transit were all needed if satellite navigation were to be truly successful.

On April 17, 1973 the US Department of Defense authorized the creation of the GPS Join Program Office with Parkinson as its lead. Over large meeting held over the Labor Day weekend in 1973, Parkinson was able to convince his cohorts in the military on a design for a system. The decisions about the system made at that meeting still prevail today.

Approval was given to start work on 22 December 1973. Initially called “Navstar” and later “Navstar/GPS” and then simply “GPS” it was given a starting budget of US$150 million. It eventually cost around US$12 billion to build and deploy. Today the operational costs of GPS are about US$2 million per day.

Over the next 15 years GPS development proceeded apace. Between 1977 and 1979 more than 700 different tests were conducted and various test satellites were launched.

Well after midnight on 19 July 1977, a Rockwell Collins engineer named David Van Dusseldorp sat on the rooftop of a company building in Cedar Rapids, Iowa, adjusting an antenna every five minutes to receive a signal from the world’s first Global Positioning System (GPS) satellite, known as NTS-2.

His GPS receiver was a little more cumbersome than one you might be used to using today:

Over the subsequent years more and more satellites were deployed. It took until 1985 before the production and development stage began. The first “Block II” operational satellite was launched in February 1989:

GPS got its first test in 1990 following the Iraqi invasion of Kuwait where the system provided invaluable navigational information to all branches of the allied forces. Media’s coverage of GPS’s use in the war helped increase awareness of the system and helped stimulate commercial interest.

By the time GPS was fully operational its future success was virtually guaranteed.

Getting to Where We Are Today

Initially the US Department of Defense kept GPS just for themselves. There was no access for commercial or consumer use.

But everything changed on September 1, 1983 when a Korean Airlines 747 jumbo jet en route from Anchorage to Seoul strayed into Soviet airspace and was shot down by a Sukhoi Su-15 interceptor. All 269 passengers and crew on board perished.

As a result of the incident president Ronald Reagan issued a directive making GPS freely available for civilian use.

But Reagan’s directive wasn’t sufficient to support consumer navigation as we know it today. The US government had implemented a filter called ‘Selective Availability’ which degraded the accuracy of the GPS signal for civilian use. It added intentional time varying errors of up to 100 meters (>300 feet) to prevent enemies of the US using civilian receivers for weapons guidance. So… no sat-nav systems yet suckers!

But there was a workaround. Because Selective Availability affected every GPS receiver in a given area almost equally, a fixed station with a known position could transmit the error to other receivers in the area. This methodology got a name: Differential GPS or DGPS.

DGPS became so effective that it essentially overcame the original intent of Selective Availability. Eventually common sense prevailed and president Clinton ordered Selective Availability to be switched off on 1 May 2000.

What of nefarious groups using GPS? Well the US military developed a new system that provided them the capability to deny GPS to hostile forces in a specific area of crisis.

Of course with the advent of GPS other nations around the world were suddenly at a serious disadvantage. Friendly nations were beholden to the US. Enemies of the US were suddenly in deep, deep yoghurt. So of course other systems sprung up:

Of note: you’ll see all these systems listed in the location specs for iPhone.

Now Don’t Go Thinking GPS is Infallible…

So when you open up you favorite mapping app you’ll see that little blue dot magically zooming to your current location.

So you might think all the app is doing is simply taking a GPS reading and plotting it on the map.

Ha, sucker. It turns out it ain’t that simple.

First: it’s common that you aren’t going to get any GPS signal when you have a roof over your head.

Second: if you’re in a city with tall buildings those GPS signals are going to bounce of the side of the buildings like a ping pong ball and as a result give you all kinds of false readings.

Third: it helps to stay still. If you’re moving you’re going to get a less accurate GPS reading. The faster you move the worse it gets.

The iPhone specs give you a clue that it takes more than GPS to get that nice blue dot:

Notice “Wi-Fi” and “Cellular”? Those two in particular play a big role in keeping your blue dot roughly correct.

In lieu of GPS a rough position of your phone can be determined by looking at which cell phone towers your device is seeing and triangulating a position from that:

It works, but only roughly (typically in the region of a few hundred meters).

Wi-Fi positioning works using a harvested database of known Wi-Fi router (a.k.a. Wi-Fi access point) locations. Similar to the idea behind cell phone tower triangulation where you know the location of the cell phone towers, this methodology works in roughly the same way.

But you need to build up a database of Wi-Fi router locations to make it work. Google got into a shit load of trouble for harvesting this data secretly back in 2008-10. How did Apple get access to similar information? Frankly, I’m not sure, but I’m guessing it was harvested from those billions of iOS devices that have a habit of wondering around.

Another way to keep the location accurate is to use location history. If at one point you know you’re at a specific location and then your phone’s compass and movement sensors see you heading in a particular direction at a particular speed then you can deduce your position at a later point in time. This methodology is called ‘Dead Reckoning‘. It has its limitations, but it stops the blue dot from jumping around too much.

Another method is to use known information about your current method of traveling. If you’re in navigation mode in your car, then hopefully it’s quite likely that you’re actually driving on a road. So the app can ‘snap’ the blue dot to the road.

As I’ve already opined there is a need for an accurate location across many, many applications and industries. As such much effort, time and money is being spent to improve location accuracy.

One method is called RTK (Real Time Kinematic) and was invented in the early 1990s. Basically it’s an evolution of the Differential GPS methodology that was used as a workaround for Selective Availability. It relies on a group of geographically distributed basestations on the ground that are at known locations.

In the last few years the big boys have introduced yet another way of determining your location. It’s called ‘Visual Localization’ and matches what your phone’s camera sees to a known database of 3D buildings. Apple Maps introduced this capability three years ago:

Indoor Positioning

Getting your position inside a building is a tough cookie. Several approaches have been tried and one of the most common “solutions” has been to push the idea of triangulation using Bluetooth beacons. Little do people know that in order to make it work you have to carpet bomb buildings with hundreds (if not thousands) of beacons. And then you have to replace the batteries in them every few months. Net/net: it doesn’t scale baby.

Another approach, used by Apple, is to employ a method called Wi-Fi fingerprinting. Apple’s Indoor Positioning system relies on this method by recording the interference patterns of the Wi-Fi radio signals inside a building. It’s also not infallible but at least you don’t have to install huge mountains of beacons.

The topic of indoor positioning is worthy a whole separate Map Happenings post. There are just so many misconceptions about so called “solutions”.

Underground Positioning

Have you ever wondered how two tunnel boring machines can start burrowing a tunnel many miles apart and miraculously end up meeting in near perfect alignment? It’s always fascinated me anyway. Particularly when these machines weigh thousands of tonnes and, well, have a tendency to sink.

GPS, Wi-Fi and Cellular methods are obviously not suitable. So how do they do it? The answer is using laser guidance. One of the leading companies to provide a solution in this space is a German company called VMT. Here’s a short video from their web site [click to play]:

Where Next?

With recent scary stories like the one about the Russians equipping their satellites with nuclear weapons, nations around the world are naturally nervous about the vulnerability of their satellite positioning systems. For example, GPS relies only on 24 active satellites to make it all work. You only have to knock a few out and GPS is pretty much kaput.

As a result the US Space Force is eyeing smaller, cheaper satellites to augment the GPS constellation. This would not only reduce the costs of the overall system but it could additionally reduce its vulnerability.

And it also sounds like everyone’s BFF, Elon Musk, could be considering a commercial positioning system.

But I’ll leave you with one more positioning technique that is currently being researched by Hiroyuki Tanaka at the Earthquake Research Institute of The University of Tokyo. Here’s his paper in published in the esteemed journal, Nature, and a subsequent one published in Cell.com.

The concept is to utilize the relativistic and penetrative nature of cosmic-ray muons, thereby developing a completely new wireless navigation technique called wireless muometric navigation system (MuWNS). To quote the paper’s authors:

This paper shows the results of the world’s first physical demonstration of MuWNS used on the basement floor inside a building to navigate (a person) in an area where global navigation satellite system (GNSS)/ global positioning system (GPS) signals cannot reach. The resultant navigation accuracy was comparable or better than the positioning accuracy attainable with single-point GNSS/GPS positioning in urban areas

Yes, dear reader. Muons.

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Footnotes:

1. Source: Frederica Lariccia at Statistica: Number of smartphones sold to end users worldwide from 2007 to 2023 ↩︎

References and Acknowledgements:

• Steven R. Strom: “Charting a Course Toward Global Navigation“. Steven is the corporate archivist for Aerospace Corporation
• Aerospace Corporation: “The History of Aerospace“
• The Institute of Navigation (ION): Navigation Museum
• Galileo GNSS: “First GPS signal received 40 years ago“
• Mark Burdon and Alissa McKillip: “The Google Street View Wi-Fi Scandal and its Repercussions for Privacy Regulation“
• Wikimedia for Wikipedia. Where would we be without you?
• VMT GmbH