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How Pressure Sensors Can Improve GPS Accuracy

GPS is Everywhere

Chances are that you are carrying a GPS device with you right now. What was once limited to military and commercial applications expanded to automobiles and dedicated GPS devices for consumers. Today, most portable electronic devices, such as smartphones and tablets, have a built-in GPS receiver with various mapping applications that can be used to pinpoint your location or provide directions to another locale.

How GPS Works

GPS receivers communicate with satellites to determine three values:

  1. Latitude of the GPS receiver: latitude specifies the device’s location distance north or south of the equator.
  2. Longitude of the GPS receiver: longitude specifies the device’s location distance east or west from an imaginary line connecting the North and South Poles, called the Prime Meridian.
  3. Elevation of the GPS receiver: elevation specifies the device’s distance above (or below) sea level.

These three values become a three-dimensional geographic coordinate system that determines a location on Earth. Latitude and Longitude are measured in decimal degrees, while elevation is typically measured in inches (for precise needs) or meters.

Mapping software takes these coordinates as input value to plot the device’s position on a map. As the device moves, the three-dimensional coordinates are constantly updated, and the software updates the plot on the map.

Pressure Sensors Improve 3-Dimensional GPS Accuracy

GPS signals can be impacted by structures. In urban areas, buildings, tunnels and other covered areas can obscure and degrade the signal the GPS receiver gets from satellites. This can impact all three coordinates: latitude, longitude and elevation.

Of the three coordinates, pressure sensors can help a GPS application more accurately determine the elevation of the device. Specifically, a barometric pressure sensor can be used to augment the GPS signal in determining the device’s height above sea level.

There are many instances when knowing the accurate altitude of a position is important. For example, there are many indoor applications where GPS is valuable. Whether it be an office building, shopping mall, multi-story parking structure, stadium, airport, etc., looking for someone or something is a lot easier if you know which level you need to go to.

Another indoor application for GPS is tracking valuable assets. Asset tracking, knowing the exact location of an item, is important in many commercial and industrial applications. Knowing where something is located in a large, multi-story complex is difficult if you cannot determine its what floor it is on.

Barometric pressure sensor makes accurate indoor navigation a possibility, and are built-in in many electronic devices, including most of the newer smartphones. Apple has been integrated barometric sensors since the iPhone 6. Many of the leading Android smartphones from Samsung, OnePlus and others also include barometric pressure sensors.

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Figure 1 – Using GPS in a shopping mall

NimbleSense Architecture Improves GPS Elevation Measurement

Having an extremely low noise floor, the NimbleSense architecture is ideal for the precise indoor elevation measurements that GPS solutions require to maximize their accuracy and performance. Not being impacted by external interference and noise, Superior’s barometric and absolute pressure sensors provide more accurate readings typically within ±6 inches that greatly reduce potential calculation errors. This is extremely beneficial in many IIOT (Industrial IOT) applications in factories, distribution centers, and large facilities such as airports and parking structures. In many of these use cases, this higher level of accuracy can directly lead to improvements in factory output or distribution center efficiency.

Warehouse sketch
Figure 2 – Warehouse with packages at multiple elevations

However, the NimbleSense advantages extend beyond the low noise floor as the architecture’s advanced digital filtering provides additional benefits. Industrial and other devices with embedded GPS are subject to external sounds, vibrations and rapid movements, all of which can impact the accuracy of pressure sensors. Utilizing our integrated advanced digital filtering technology, Superior’s pressure sensors eliminate the noise created by these factors before they can impact product performance. Thus, the noise is eliminated before it becomes an error signal that can lead to inaccurate readings.

Conclusion

GPS receivers are with us almost all the time. In addition to mapping X,Y coordinates, they are being used more often indoors. In order to accurately measure indoor locations (thus expanding from X,Y to X,Y,Z), barometric pressure sensors are used to determine the altitude of the device (the Z coordinate). Barometric and absolute pressure sensors provide an easy, cost-effective solution. Superior Sensor Technology’s pressure sensors offer the highest levels of accuracy due to the NimbleSense architecture that has the industry’s lowest noise floor and advanced digital filtering.

To learn more about the NimbleSense architecture, please visit our technology page. If you have a GPS project you would like to discuss, please contact us.

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