32.3 DIFFERENTIAL GPS

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32.3 DIFFERENTIAL GPS

As shown in Figure 32.3, in differential GPS (DGPS), there is a reference station (a surveyed location with exactly known longitude, latitude, and altitude). This reference station has a GPS receiver as well as an FM transmitter. This station receives the GPS signals and computes its location parameters. These parameters are compared with its own known location parameters to calculate the error of the GPS receiver. The error correction to be applied to the results of the GPS signals is thus calculated, and this information is broadcast to all the GPS receivers around the reference station using the FM transmitter.

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Figure 32.3: Differential GPS system.

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The differential GPS receiver consists of a GPS receiver that gets the signals from the GPS satellites and an FM receiver that gets the signals from the FM transmitter located at the DGPS base station. Based on these two signals, the DGPS receiver calculates its position parameters accurately.

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The DGPS receivers of all users are fitted with FM receivers in addition to the GPS receivers. The DGPS receiver obtains the location parameters from the GPS data and then applies the correction based on the information received on the FM channel. This results in obtaining more accurate location parameters.

Using differential GPS, location accuracy up to one meter can be achieved. For applications that require high accuracy, such as surveying or defense applications, differential GPS needs to be used as instead of normal GPS.

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Using differential GPS, one meter accuracy can be obtained. Such high accuracy is required for applications such as surveying and missile guidance.

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Principles of Digital Communication Systems and Computer Networks
Principles Digital Communication System & Computer Networks (Charles River Media Computer Engineering)
ISBN: 1584503297
EAN: 2147483647
Year: 2003
Pages: 313
Authors: K V Prasad

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