GPS receivers are categorized into different types by its purposes, frequency
and channel.
A. By Purposes
1. Aviation GPS receiver: It is mainly used in aviation of moving carriers.
It tells locations and speed of the moving carrier in real time. Measured
psychologically with C/A number, so its single positioning is less precise which
is about -25 MM. If affected by SA, the differences can be -100 MM. The kind
of GPS receivers is less expensive and widely used in various industries.
2. Ground GPS receiver: It is mainly used in precise ground and engineering
measurement. It uses the value of carrier phase to measure the relative
position, so the result is precise. The receiver is built complicatedly, so the
price is highers.
3. Time transfer GPS receiver: It transfer time by highly precise satellite.
It is usually used in the the observatory and wireless communication.
B. By Frequency
1. Single-channel GPS receiver: It only receives signal of L1 carrier wave
and positions by value of carrier phase. It can't eliminate the affect of
ionosphere delay, so it is only applicable for precision position of ultra short
base line less than 15 KM.
2. Double-channel GPS receiver: It can receive carrier signals of both L1 and
L2. With its differences to ionosphere delays, the delay of electromagnetic wave
signal caused by ionosphere can be eliminated. Therefore, it can be used in
precision position for thousands of kilometers.
C. By Channels: GPS receivers can receives signals transmitted from multiple
GPS satellites at the same time. It uses antenna singal channel to separate the
signals received and track, handle and measure individual satellite. The
channels are divided into multi-channel receiver, serial channel receiver and
multi-channel receiver.
