4.5 Radio Navigation System
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In addition, there are also three hyperbolic navigation systems, including the
British Gee, the Soviet (later Russian) Alpha and Chayka, and the Chinese Changhe2. The Gee was a pulse timing radio navigation system similar to LORAN-A, and
began to provide service for the British Royal Air Force in 1942, with the positioning
accuracy on the order of a few hundred meters within a range of 560 km. The Alpha
(also known as RSDN-20), a hyperbolic navigation system similar to the Omega, was
developed by the Soviet Union in 1962, and later evolved into the Russian terrestrial
radio navigation and timing system similar to the LORAN-C, called Chayka, using
a working frequency of around 100 kHz. The Chayka is available across the entire
western portion of Russiaincluding Moscow, the Baltic Sea and Black Sea, as well
as in the eastern portion of the country including the Seaof Okhotskand the northern
portion of the Sea of Japan. The Changhe-2, a terrestrial medium and long-range
radio navigation and timing system, was independently developed by China, with
the signal coverage of the China’s coastal and related sea areas. In 1990, it was
officially opened to a variety of users.
4.5.3 Doppler Navigation System
The Doppler navigation system is a radio navigation system which based on the
principle of Doppler shift generated by radio signals takes the distance change rates
of the movable objects relative to the signal transmitting stations as the observables,
to determine the positions of the movable objects. The typical Doppler navigation
system can be divided into two types: one is Doppler radar navigation and another
is Doppler counting navigation.
The Doppler radar navigation belongs to an autonomous dead reckoning system,
mainly used for aircraft navigation. The aircraft’s velocity information is measured
with the Doppler radar, and its course and attitude are provided by the special attitude
reference system, so as to obtain the velocity vector of the aircraft relative to the
ground coordinate system. And thus, by integrating the velocity about time once, the
position coordinates of the aircraft can be gotten eventually. In 1945, the Doppler
radar for measuring speed had occurred. In 1955, the military aircrafts began to
use the Doppler radar navigation, crossing through the development stages from
electronic tube to transistor, combination and integration. At present, the Doppler
radar navigation is a quite mature technique and has become the general navigation
equipment for all kinds of aircrafts.
The Doppler counting navigation is mainly used for satellite’s orbit determination. Generally, in order to improve the accuracy of measuring Doppler shift,
the Doppler shift at an epoch is not measured directly, but the cumulative value
of the Doppler shift within a given time interval is measured indirectly, which is
called Doppler counts. The measurement equations can be established by using
the Doppler counts from multiple time intervals, and then by combining the system
state equations, the navigation parameters of the movable objects can be estimated
with the Kalman filtering. Doppler Orbitography and Radiopositioning Integrated by
221
In addition, there are also three hyperbolic navigation systems, including the
British Gee, the Soviet (later Russian) Alpha and Chayka, and the Chinese Changhe2. The Gee was a pulse timing radio navigation system similar to LORAN-A, and
began to provide service for the British Royal Air Force in 1942, with the positioning
accuracy on the order of a few hundred meters within a range of 560 km. The Alpha
(also known as RSDN-20), a hyperbolic navigation system similar to the Omega, was
developed by the Soviet Union in 1962, and later evolved into the Russian terrestrial
radio navigation and timing system similar to the LORAN-C, called Chayka, using
a working frequency of around 100 kHz. The Chayka is available across the entire
western portion of Russiaincluding Moscow, the Baltic Sea and Black Sea, as well
as in the eastern portion of the country including the Seaof Okhotskand the northern
portion of the Sea of Japan. The Changhe-2, a terrestrial medium and long-range
radio navigation and timing system, was independently developed by China, with
the signal coverage of the China’s coastal and related sea areas. In 1990, it was
officially opened to a variety of users.
4.5.3 Doppler Navigation System
The Doppler navigation system is a radio navigation system which based on the
principle of Doppler shift generated by radio signals takes the distance change rates
of the movable objects relative to the signal transmitting stations as the observables,
to determine the positions of the movable objects. The typical Doppler navigation
system can be divided into two types: one is Doppler radar navigation and another
is Doppler counting navigation.
The Doppler radar navigation belongs to an autonomous dead reckoning system,
mainly used for aircraft navigation. The aircraft’s velocity information is measured
with the Doppler radar, and its course and attitude are provided by the special attitude
reference system, so as to obtain the velocity vector of the aircraft relative to the
ground coordinate system. And thus, by integrating the velocity about time once, the
position coordinates of the aircraft can be gotten eventually. In 1945, the Doppler
radar for measuring speed had occurred. In 1955, the military aircrafts began to
use the Doppler radar navigation, crossing through the development stages from
electronic tube to transistor, combination and integration. At present, the Doppler
radar navigation is a quite mature technique and has become the general navigation
equipment for all kinds of aircrafts.
The Doppler counting navigation is mainly used for satellite’s orbit determination. Generally, in order to improve the accuracy of measuring Doppler shift,
the Doppler shift at an epoch is not measured directly, but the cumulative value
of the Doppler shift within a given time interval is measured indirectly, which is
called Doppler counts. The measurement equations can be established by using
the Doppler counts from multiple time intervals, and then by combining the system
state equations, the navigation parameters of the movable objects can be estimated
with the Kalman filtering. Doppler Orbitography and Radiopositioning Integrated by