The US has 31 active GPS satellites in orbit above the earth. GPS equipped gadgets have become an essential part of our lives –from cars to smartphones.
Today, it has become impossible to get lost, no matter how hard you try. Walking with a smartphone in your pocket, you will have access to a GPS receiver with your exact position, no matter where you are.
Besides helping people reaching the destination safely, there are other uses as well.
This article explores everything you need to know about GPS and even how GPS works in car.
GPS Definition and How GPS Works
GPS, aka Global Positioning System, is a satellite-based navigation system made of a minimum of 24 satellites. These satellites orbit Earth at an altitude of about 12,500 miles (20,000 km).
It works 24*7 across the globe regardless of the weather conditions. There is also no set up charges or subscription fees to use it.
GPS Satellites flying orbital flight around Earth.
Components of GPS
GPS is a three-part system that includes:
a) Satellites – They serve like stars in the constellation.
b) Ground stations – They monitor and control satellites. Ground stations also identify their location.
c) Receivers – Receivers are constantly listening for signals from the satellites. Highly advanced receivers can even identify the exact location within a fraction of an inch.
Interesting GPS Facts
1. The original idea of the Geo Positioning System based on LORAN and Decca Navigation System. Both were used during World War II to help in the ship and plane navigation in a long-range.
2. The 31 GPS satellites are US-owned. Each GPS satellite orbits earth (a full revolution) every 12 hours.
3. GLONASS is the Soviet version and consists of 24 satellites. They are in a faster orbit at 11,900 miles above earth and orbit in 11 hours.
Note: You can actually see satellites orbiting the earth at night if you are in a dark area with no city lights around. Lay flat on your back and look up, give your eyes time to adjust.
They look like tiny stars moving fast through the sky.
3. Doppler Effect is the fundamental principle used in GPS. Change in signal frequency from the GPS satellites help in determining locations and speed.
GPS uses Doppler Effect
The Doppler Effect is critical to GPS functionality and many other systems in our world today, so it bears explaining.
All things are transmitted at a certain speed, i.e. light, sound, etc. So, if someone was running toward you and they threw a ball at you, the speed of the ball coming at you is their speed + the ball speed leaving their hands. If they are running away from you and threw a ball at you, the speed of the ball is ball speed – their speed.
This is the foundation of Einstein’s Special Theory of Relativity, as he proved this with the speed of light.
4. Before GPS arrived, the navy navigation system was in use. Their requirement of the speedy navigation system forced them to think whether the navigation system using satellites is possible.
5. In 1983, the Soviet Union shot down Korean Airlines flight as the flight moved through Soviet airspace. This incident made Ronald Reagan give public access to GPS for free.
6. When the Soviet Union launched Sputnik in 1957, two American physicists started monitoring the signal transmission of the satellite. They realized that they could determine the satellite in its orbit via Doppler effect.
7. Early on, GPS was named Navstar. The first Navstar satellite was launched in 1978. The first completely built satellite unveiled in the year 1989.
8. GPS was introduced in automobiles in 1996.
9. If you thought GPS is only associated with navigation, you were wrong. You can also use it to identify the correct time.
Each satellite possesses time signals and atomic clocks that GPS can use to transmit the right time. This time is critical to the GPS functionality and gives the ground receiving device the ability to calculate its distance and location.
10. Bradford Parkinson, Ivan A., and Roger L. Easton invented a GPS navigation system.
11. A man invented shoes known as ‘No Place Like Home.’ They have a built-in GPS that guides the person to home by clicking heels together three times.
12. The current worldwide market for GPS technology and is approximately over $2 billion. It is expected to increase over $30 billion in the next ten years.
GPS History – How the Global Positioning System Came to Be?
The Global Positioning System has its trace in the Sputnik era, where scientists use the navigation system to track the satellite with shifts in radio signal (Doppler Effect). This satellite was launched into orbit by the Soviet Union in October 1957.
US Navy performed satellite navigation experiments in the mid-1960s to track US submarines.
With 6 satellites orbiting the poles, submarines tracked satellite changes via Doppler and found the exact location of the submarine with few minutes.
The United States government initially innovated GPS for military use. Their need for a global navigation system arose during the cold war. Today the Global Positioning System is owned by the US Government and run by the US Air Force.
In the early 1970s, the US Department of Defense wanted to create a strong and reliable satellite navigation system. So using past ideas from navy scientists, they decided to use satellites to support the proposed navigation system.
DoD then launched its first navigation system, ‘NAVSTAR,’ in 1978. This system became completely operational in 1993.
At present, GPS offers two levels of service:
a) Standard Positioning Service
b) Precise Positioning Service
PPS use is limited to United States federal companies, Armed Forces, and governments. SPS is available to any person for use without any charge with GPS receiver. There are more GPS receivers for civilians than military use.
However, early civilian GPS systems were bulky and big. But they were not that accurate.
To prevent intruders from using the navigation details, the US government used dithering. These global positioning systems were made available to common people for use in the year 2000s.
GPS Satellite Functionality
Each GPS satellite sends a unique signal to allow a GPS enabled device/receiver to decode and calculate the exact location of the satellite. The signals move at the speed of light, the receiver knows this, and this helps in the mathematical calculation to determine its position.
The GPS receiver uses this data to calculate the location of the user and show it on the electronic device using a process known as ‘Trilateration.’ It works by measuring the distance to each satellite by the total time it takes to receive a transmitted signal.
To compute the 2D position and track movement, the GPS receiver unit must lock on to the radio signal of a minimum of three satellites. Remember, four or more satellites allows the receiver to identify 3D positions.
Typically, a GPS receiver can track eight or more satellites, but this depends on your location on Earth and the time of the day.
GPS Satellites and Signal Data
To complete the mathematical calculation; the GPS receiver uses the correct position of at least four satellites. The distance to each satellite estimates four crucial values:
Once GPS identifies the user position, it can calculate other metrics based on your next position and subtracting time and distance, such as:
Distance to destination
Sunrise, and sunset time
GPS Transmitted Signals
GPS satellites transmit at least two low-power radio signals. These signals are packed with three types of data:
GPS Location from Trilateration
a) Pseudorandom Code
Each satellite has a unique pseudorandom code that identifies which satellite is transmitting data. It is a complicated code that contains a sequence of 1s and 0s.
Signal is so complex that it appears like random electrical noise. That is why, sometimes, it is known as pseudo-random.
b) Ephemeris Data
GPS satellites transmit details about the current time, location, and health through ephemeris data. Then use this data to estimate position relative to other satellites.
c) Almanac Data
GPS almanac data is the data that GPS satellite transmits throughout the day. It includes details like data in every satellite and state of the whole GPS satellite constellation. This data helps the device locate an area of eligible satellites and get a “fix” much quicker.
Some Uses of GPS
GPS Technology offers a lot of advantages:
Locating the position of the person in real-time and getting instant notifications is one of the biggest uses of GPS. It is a perfect tool for adventure lovers.
This is because the Global Positioning System helps them arrive at their destination safely and on time by displaying the best route available. This makes this tracking device one of the safest systems on the market.
Support in Emergency
Did you know approximately 2,000 people get lost in the woods every year?
So whether you get stuck in an isolated region or have an accident, features such as real-time tracking, route history, geofence zones, and alerts allow you to call emergency numbers on your smartphone.
The bonus point is that it works even if you forget to share your location details with the emergency crew.
Prevent Car Theft
GPS can serve as a great anti-theft device. By installing it in your vehicle, you can track and locate it in case of theft.
Many companies use GPS in surveying and mapping projects to save money and time. These projects include crops, soil types, highways, etc. The point of GPS application is that surveyors can position it at a single point and set a reference marker.
Moreover, the valuable information obtained from the app can be transferred quickly into the software, allowing for a detailed chart.
Did you know Caracas, Venezuela is on top when it comes to crime?
Law enforcement, investigators, and police officials also use a GPS to catch criminals. They do this by adding a small GPS device on the vehicle of the suspect to track the location. It also helps them collect other valuable details too.
Find Lost Pets Quickly
Are you an avid pet lover? If yes, add a small GPS tracking device to their body. If your pet is lost, you can use it to locate them quickly.
Keep an Eye on Seniors or Disabled People
Another big benefit of GPS technology is you can use it to keep an eye on the elderly or disabled loved ones. There is a small button on these devices that seniors can press to make emergency calls for immediate medical help. SOS alarm notifies you when your loved one pressed it.
Did you know 5% of people in America ages 65 to 75 have Alzheimer’s disease? It is also ranked as the sixth leading cause of death in the United States.
In fact, statisticians also predict that in the next thirty years, 13.8 million people may be facing Alzheimer’s if researchers are not able to prevent or find a cure.
So if you have a loved one in your home that needs special care, you can use a GPS Tracker for peace of mind.
Today there are tons of GPS enabled devices you can add into the clothes or footwear of the elderly to track them.
Protect Costly Artistic Pieces
Owners of valuable paintings and artwork protect their assets by installing a small GPS device in them. The moment it moves away from their location, it sends an email or text message to the owner to trace the location and get the artistic piece back.
Technology geeks also use Global Positioning System to see treasure hidden on sites.
GPS saves lives and ensures speedy recovery of victims in case of global disaster. Location information coupled with automation effectively lowers delay in dispatch of emergency services and supplies. In fact, it operates in any kind of weather, anytime and anywhere.
Meteorologists use this modern technology for the prediction of storm and flood. They use GPS to assess water vapor content by analyzing data transmissions via the atmosphere.
Another benefit of GPS is a real-time tracking and live streaming video recording.
Easy Linking to Tablet, PC or Mobile
You can even link your vehicle tracking system to your tablet, mobile, or PC to monitor location in real-time.
GPS App in the Car
GPS Satellite Navigation
Satellite navigation (or Satnav) means the use of a portable radio receiver that picks up the GPS signals from orbiting satellites. It is usually more accurate than other forms of navigation.
Since it’s a broadcast system, so any number of people can use it. Navstar Global Positioning System is the popular Satnav system that uses 31 active satellites.
A GPS Tracker is a system used to track the precise position of any person or vehicle in a real-time scenario. It updates location using GPS Satellites, Bluetooth, and Wi-Fi.
It must be in direct line of sight to at least three different satellites to triangulate the exact position. That is why most of the GPS trackers use Wi-Fi routers for the massively dense regions and indoor tracking.
However, to obtain a precise location from the Wi-Fi router, you require a Wi-Fi chipset in the tracker. These Wi-Fi routers work in the same way as satellites. However, it’s not as accurate as getting the location from satellites due to the fact that the router has an approximate address and not a precise location.
How GPS Works in Car
Cars can contain many products that have GPS inside them. For example, Car Navigation and GPS Trackers will use the same GPS described above to get your location.
So, even if the car is moving fast, as long as these devices can receive GPS signals, they will work fine.
There are things that will prevent the GPS signals from being received in a car, like bad weather, and clouds can block GPS signals.
A poor install location, like, in the trunk, may block the signals, also.
There are 3 Types of GPS Tracking Devices:
a) Data Pushers
Data pushers are GPS tracking units that are used for tracking any vehicle, person, or asset. In asset and personal tracking, the location of a particular person or vehicle is sent to the server over short time intervals.
However, in-vehicle tracking, GPS tracking unit doesn’t just send vehicle position to the server but also analyze the speed and other data needed.
b) Data Pullers
Data Pullers track location the same as data pushers. However, the main difference is that data pushers do not send any data to the server. Instead, it requests to send the information.
On the other hand, data pullers are always switched on and can be used to extract information at any time.
c) Data Loggers
Data Loggers store the position of vehicle, speed, and heading in its internal memory. However, it does not send any data to the central server but can do so when retrieved by the user/owner.
GPS Tracking System
GPS Tracking systems also use GPS receivers as described above.
However, instead of displaying the current location on-screen on the equipment, it will transmit it to the server using the worldwide GSM cellular network or other radio signals.
The server hosts a platform that end-users can access and see current and past speed, historical path, and other information.
All the data is transmitted using the web and shown on the device of end-user utilizing a smartphone, or desktop application.
GPS Works in a Car or Truck
In case GPS satellite signals get blocked, the GPS tracker looks for cell tower signals to estimate the location. Thus, the tracker tracks the device location and roughly calculates the distance between cell phone towers and adjacent towers.
Types of GPS Receivers
GPS Personal Trackers
Personal trackers track people or even pets. They work via their own devices such as a bracelet or pocket chip. They are pocket-sized and can be added to the pet collar or backpack of a person for easy tracking. But you need to activate them to locate and follow the device remotely.
GPS Asset Trackers
Asset trackers are used to track non-vehicular things, like boxes, crates, etc. GPS Tracking can be used in conjunction with RFID chips and satellite tags.
GPS Vehicle Trackers
As mentioned in the previous section, How GPS Works in Car, GPS is perfectly suited for use in a car.
GPS Car Trackers use cell-based racking. Cell-based trackers are most common. They collect data from a vehicle using the internet and then send it using cell towers.
See our article on Choosing a GPS Tracker.
Remoter users can access tracking information using a secure web connection or smartphone application.
Plug-In GPS Trackers
Plug-in GPS trackers are easy to install into the port of a car. The port offers power and information to GPS trackers. They alert the owner of the vehicle is turned on or off. They are ideal for both business and personal use.
Hardwired GPS Trackers
Hardwired GPS Trackers have a wire that fits into the vehicle. They offer more flexibility than a plug-in model. Since they are not attached to the port, they can be installed anywhere under the dashboard or other parts of the vehicle.
Battery Powered Trackers
Battery Powered GPS Trackers are independent of the power system of the vehicle. They have long battery life and broadcast to monitors. They report to the network after sensing motion or at specified intervals.
GPS hidden in a package
Fitness GPS Trackers
Fitness GPS trackers are ideal for those who want to line an active and healthy lifestyle. These wristwatch-like trackers measure calories burned, number of steps, pacing, and distance covered.
Marine GPS Trackers
Marine GPS trackers are the most advanced trackers. They feature a marine database and identity buoys and sound signals used in navigation.
How to Choose GPS Tracker?
When picking GPS trackers, consumers to decide if they need a passive or real-time tracker.
Passive trackers do not allow users to follow every motion of an object or person. Users need to gather and download the data into a computer. These trackers are usually cost-effective as they do not have any charges.
Active trackers processes and offers information in real-time using GSM transceiver or SIM. Dispatchers get the data via GSM cellular network. If consumers choose these services, they need to pay monthly fees.
To learn more about choosing a GPS Tracker, see our article here.
How Accurate is GPS?
GPS receivers available today are very accurate. Thanks to the parallel multi-channel design. When switched on, they quickly lock onto satellites and they maintain a tracking lock even in urban settings or regions with highly dense trees.
Factors that can Affect GPS Accuracy
Here are some of the factors that can directly affect GPS signal accuracy:
a) Quality of the GPS Receiver
Remember, the receiver with the clock is not as accurate as an atomic clock in the satellite.
b) Position of the Satellites
Satellite positions at the time the data recorded can also affect GPS accuracy. For example, poor satellite geometry occurs when they are in tight groups or a line. Satellite signals are correct when located at wide angles to each other.
c) The Characteristics of Surroundings
Multi-path effects happen when radio signals get bounced around when coming in contact with buildings, valleys, tree cover, etc. The increase in the travel time causes room for errors.
Use a narrow collector method to identify the long delay of signals.
There are also specially-built antennas that you can use to measure accurate data signals that get slightly deviated or delayed.
Try modern high-sensitivity GPS receivers to track signals when under tree-cover or inside buildings.
d) Weather Conditions
Any change in the atmosphere can affect GPS radio signals. Both the ionosphere and troposphere can leave a minimum or massive impact on the speed of radio signals.
Tips: Take into account dual-frequency measurement to lower flaws. It will also identify the precise location of the receiver.
e) Artificial Degradation of Signal
US Department of Defense has restricted the public to use some accurate GPS signals. Their main aim is to stop any misuse. Due to this, some intentional errors may come, such as transmitting wrong orbital information, noise in the satellite clock, etc.
But the government turned off selective availability (SA) in May 2000 to enhance the accuracy of GPS receivers for civilian use.
f) Number of Satellites Visible
More satellites a GPS receiver can spot, the better is the accuracy. When the signal gets hindered, you may get position errors or no position at all. Remember, GPS units do not work underground or underwater.