GPS receiver module basics

This page covers GPS receiver module basics.It mentions GPS receiver module application note and GPS module manufacturers.

As we know the GPS device will have GPS receiver which obtains the position information from GPS satellite. The position contains latitude, longitude and height co-ordinates.

LNB (Low Noise Block Converter) and other modules/subsystems are needed as shown in the figure below in order to recover S/N above the threshold. This is needed to recover error free data informations from the received C/N.

GPS receiver application note

Refer GPS transmitter part which is nothing but GPS satellites rotating in the the space segment.

To recover the baseband information from the received GPS signal from the GPS satellite, costas loop is used with phase synchronized LO otherwise signal can not be detected. The needed PN code is locally generated to detect the chip of spread spectrum of received signal. The number of correlators here depend on number of visible GPS satellites in the sky. Most of the GPS receivers will have 12 correlators.

LNB stands for Low Noise Block Converter which is combination of both LNA and RF converter. Software ported on CPU is used to calculate X,Y,Z co-ordinates which in turn helps in calculating latitude, longitude and altitude.

GPS receiver perform two measurements using received GPS signals.

• Compare received C/A code or P code with the code generated locally using look up table. This will help determine delay between GPS satellite and GPS receiver. This measurement is called pseudo range.

• The other method is used to obtain phase difference between received carrier signal and signal generated locally at the receiver at same frequency. This technique provides measurement with millimeter precision. This is not accurate method as it is assumed here that received and local carriers are locked and some prior information of phase is known at the receiver which is not true.

GPS module manufacturers

Following are the manufacturers of GPS module, GPS receivers and so on.
• Broadcom
• Futurlec
• Furuno Electric Co.
• Sparkfun Electronics
• Maxim integrated
• Navsync
• Skyworks Solutions, Inc.
• Central Electronics Ltd.
• SkyTraq Technology, Inc. Taiwan

GPS RELATED LINKS

What is Difference between

RF and Wireless Terminologies