How GPS and GNSS receivers work

You’re not alone if you’re wondering how GPS and GNSS receivers work. The GPS and GNSS satellite constellations orbit the Earth, and here’s a quick overview of their constellation, frequency, and holdover period. Learn more about GPS satellites in this article! Also, find out which one is best for you. Once you have a basic understanding of these systems, you can get a good GPS or GNSS receiver.

PS and GNSS receiver works by calculating your location based on signals from several satellites. 

The global navigation satellite system (GNSS) consists of a network of artificial satellites. These satellites broadcast timing and orbital information to aid navigation and positioning measurements. The receivers use these signals to determine and report your location. These satellites perform trilateration calculations to determine your location based on your position in relation to four satellites. This method is used by GPS and GNSS receivers and can be used for both terrestrial navigation and marine navigation.

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Each satellite transmits an ephemeris that includes orbital data.

Several augmentation systems of the GPS and GNSS systems are used to improve the accuracy and reliability of the navigation data. 

Each satellite transmits an ephemeris that includes orbital data. This data contains a rough almanac for all the satellites in the constellation and a precise ephemeris for that particular satellite. These data messages are encoded in code and transmitted to the receiver. The atomic clocks in the satellites keep synchronization with each other. To determine a user’s position, the receiver compares the transmission time from three or four satellites.

GNSS receivers must receive a navigation message from a GNSS satellite.

GNSS receivers must receive a navigation message from a GNSS satellite to determine your location. The navigation message consists of four main parts: GPS time, satellite health, ephemeris, and almanac. GNSS signals help determine your position and velocity and provide accurate time. It is also used in cellular systems, power grids, and financial networks.

Receivers with four GNSS constellations can track a subset of satellites that have the highest signal quality. It increases the accuracy of velocity and position measurements.

The receiver uses the carrier phase observable to determine the correct location of the satellite

The fundamental process in how a GPS and GNSS receiver works is to track the satellite signal. The process involves receiving a signal from a satellite, mixing it with a replica carrier, and stripping codes from the incoming carrier. 

GNSS receivers use the same satellites to determine their position, and they can also provide incredibly accurate time. Their precision is so high that it is used in cellular systems, the internet, and financial networks. Ultimately, it is used for geodesy and synchronization. GPS is more than just a timepiece – it’s also a computer!

The time server will gain an error if it is unable to determine an accurate time and frequency

A reliable time source is essential for synchronizing the network. In case of a GNSS signal failure, a time server can use its internal resources to calculate an accurate time and frequency. Depending on the signal propagation conditions, a time server may also use a time source with a longer holdover period to reduce the impact of GNSS signals.

During a location acquisition, the internal oscillator in a receiver may drift, affecting the calculation of distance and arrival times. While TCXO can alleviate this drift, it increases the time needed to recalculate time and location. Using multiple satellites can help avoid such problems. GNSS receivers should be used with a backup plan, such as a GPS.

The receiver must also receive signals from up to four other GNSS satellites to compensate for errors

Modern GNSS and GPS receivers can improve satellite positioning accuracy by as much as three meters. While the three visible GPS satellites are enough to determine a person’s location, the receiver must also receive signals from four other GNSS satellites to compensate for errors. A modern GNSS receiver will typically have enough tracking channels to follow several GNSS providers, such as Galileo and Navstar. Furthermore, receivers with more receive channels will generally increase overall accuracy, reduce power consumption, and improve the cold start time of the device.