220
4 Navigations from Ground to Space
time differences between two pulse signals, but also the phase differences
between both carrier waves, and then obtains the distance differences.
For the hyperbolic navigation system, the number of users is unlimited, the user
equipment is simple and the navigation parameters can be determined without the
need of the signal transmitting devices and high-precision timing devices on movable
objects, so it has been widely used in marine navigation.
The LORAN, short for Long-Range Navigation, began to be developed in the
United States during the Second World War, and operated at lower frequencies to
provide an improved navigation range up to 2415 km, with an accuracy of tens
of kilometers. There were four LORAN series developed sequentially, including
LORAN-A, LORAN-B, LORAN-C and LORAN-D. In 1943, the LORAN-A system
was first equipped with ship navigation, and used the pulse hyperbolic positioning
way, with the working frequency of 1.75−1.95 MHz. The LORAN-B system was
originally designed by using the mid-wave pulse and phase hyperbolic positioning
way, but its development was terminated due to the technical difficulties of identifying the integer number of cycles of phase. In 1957, the LORAN-C system was
successfully developed, which used the pulse and phase hyperbolic positioning way
with the working frequency of 90−110 MHz. In the LORAN-C system, the problem
of integer cycle phase ambiguity was solved completely, and the new techniques like
the phase comparison and multi-pulse code correlation detection were then introduced, so that it had become a general navigation system for sea, land and air. In
1968, the LORAN-D system was developed, which inherited the technology of the
LORAN-C system and added the mobility of the ground signal transmitting station,
so as to become an ideal military tactical navigation system.
The Decca navigator system was a hyperbolic navigation system which used
the phase comparison of two low-frequency signals between 70 and 129 kHz to
determine the positions of ships or aircrafts. In 1930s, the Decca’s concept was
originally proposed in the United States, but later developed into an operational
system by Decca Radio and Television Company Limited of London, the United
Kingdom. In 1943, the Decca system began to be equipped with the British Royal
Navy. In 1946, the first commercial chain of the Decca’s stations was established in
southeast England. In the middle 1950s, the problem of the Decca’s phase ambiguity
was completely removed by introducing the multi-pulse technique. By the 1960s, the
Decca system was adopted by the ICAO as the standard airborne navaid in preference
of the VOR/DME.
The Omega navigation system was a very low-frequency, continuous wave and
phase hyperbolic navigation system, which had the capability of global-range navigation, with the working frequency of 10−14 kHz. It was successfully developed in
1967, and operated around 1971 by the United Statesin cooperation with six partner
countries. In the Omega system, a radio beacon network with eight fixed terrestrial
stations was deployed around the world, so that the aircrafts and ships anywhere could
receive the signals from five terrestrial stations at least, of which three stations were
selected for positioning calculation, with the positioning accuracy of two nautical
miles. Until 1997, the Omega system was shut down in favor of the GPS.
4 Navigations from Ground to Space
time differences between two pulse signals, but also the phase differences
between both carrier waves, and then obtains the distance differences.
For the hyperbolic navigation system, the number of users is unlimited, the user
equipment is simple and the navigation parameters can be determined without the
need of the signal transmitting devices and high-precision timing devices on movable
objects, so it has been widely used in marine navigation.
The LORAN, short for Long-Range Navigation, began to be developed in the
United States during the Second World War, and operated at lower frequencies to
provide an improved navigation range up to 2415 km, with an accuracy of tens
of kilometers. There were four LORAN series developed sequentially, including
LORAN-A, LORAN-B, LORAN-C and LORAN-D. In 1943, the LORAN-A system
was first equipped with ship navigation, and used the pulse hyperbolic positioning
way, with the working frequency of 1.75−1.95 MHz. The LORAN-B system was
originally designed by using the mid-wave pulse and phase hyperbolic positioning
way, but its development was terminated due to the technical difficulties of identifying the integer number of cycles of phase. In 1957, the LORAN-C system was
successfully developed, which used the pulse and phase hyperbolic positioning way
with the working frequency of 90−110 MHz. In the LORAN-C system, the problem
of integer cycle phase ambiguity was solved completely, and the new techniques like
the phase comparison and multi-pulse code correlation detection were then introduced, so that it had become a general navigation system for sea, land and air. In
1968, the LORAN-D system was developed, which inherited the technology of the
LORAN-C system and added the mobility of the ground signal transmitting station,
so as to become an ideal military tactical navigation system.
The Decca navigator system was a hyperbolic navigation system which used
the phase comparison of two low-frequency signals between 70 and 129 kHz to
determine the positions of ships or aircrafts. In 1930s, the Decca’s concept was
originally proposed in the United States, but later developed into an operational
system by Decca Radio and Television Company Limited of London, the United
Kingdom. In 1943, the Decca system began to be equipped with the British Royal
Navy. In 1946, the first commercial chain of the Decca’s stations was established in
southeast England. In the middle 1950s, the problem of the Decca’s phase ambiguity
was completely removed by introducing the multi-pulse technique. By the 1960s, the
Decca system was adopted by the ICAO as the standard airborne navaid in preference
of the VOR/DME.
The Omega navigation system was a very low-frequency, continuous wave and
phase hyperbolic navigation system, which had the capability of global-range navigation, with the working frequency of 10−14 kHz. It was successfully developed in
1967, and operated around 1971 by the United Statesin cooperation with six partner
countries. In the Omega system, a radio beacon network with eight fixed terrestrial
stations was deployed around the world, so that the aircrafts and ships anywhere could
receive the signals from five terrestrial stations at least, of which three stations were
selected for positioning calculation, with the positioning accuracy of two nautical
miles. Until 1997, the Omega system was shut down in favor of the GPS.