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4 Navigations from Ground to Space
inclinations of 90° and the periods of 106 min, and each satellite transmits navigation signals at two central frequencies of 400 MHz and 150 MHz, respectively.
The control segment is a ground network of tracking, measuring and controlling the
satellites, composed of the ground stations with known position coordinates. Its tasks
are to track each Transit satellite and measure its Doppler shift counts, estimate and
predict the satellite’s orbit and time parameters, and inject navigation message to
each satellite twice a day with the uplinks. The user segment consists of a variety of
the Doppler receivers, each of which measures the Transit satellite Doppler counts
in a given time interval and establishes the measurement equations, and then the
location coordinates of user receivers can be estimated by using the method of least
squares. The orbits of the Transit satellites were designed to pass over the North and
South Poles of the Earth, and evenly distributed on the equator. One Transit satellite
at least can always be observed at any site in the world for a given time, and the site’s
coordinates can be determined. The time interval between twice positioning is several
hours near the equator, 1−2 h in the middle latitude and less than 1 h in the polar
regions of the Earth. The goal of building the Transit system is to regularly calibrate
the inertial navigation system on board of the Polaris submarine, so the positioning
interval, even with several hours, can also meet the system-built requirements. In
other words, the Transit system is not applied to the real-time navigation for highly
dynamic users. At any site, by measuring the Doppler shift counts of a single pass
of a Transit satellite and using the dual-frequency signals to weaken the ionosphere
delays, the navigation parameters can be obtained with the positioning accuracy of
200 m and the timing accuracy of 50 microseconds [8].
In 1960s, the Soviet Union began to develop the navigation satellite system, called
Tsiklon, in order to provide the Soviet ballistic missile submarines with accurate
position fixed. As early as 1962, the draft project for a Tsiklon experiment satellite
was completed, using the Doppler navigation method, and the satellite would be
placed in 800−1000 km altitude orbits, but its development was prolonged due to
software problems and lack of accurate geodetic data. Until May 1967, the first
Tsiklon satellite Cosmos-158 with a weight of 750 kg was launched into the orbit,
with an apogee of 812 km, a perigee of 731 km and an inclination of 74 degrees to
carry out the flight tests. Subsequently, the first positioning test was conducted with a
Project-680 vessel of the Black Sea fleets, demonstrating a position error of 3 km, an
intolerable test result. In 1969, after improving the models of predicting the satellite’s
ephemerides and incorporating new information on the gravitational anomalies and
geoids of the Earth, an average position error reached 100 m over a 5-day period. On
the basis of further improving a mapping of the Earth’s gravitational anomalies, the
Tsiklon system’s tests had continued, and until 1972, the system was finally accepted
by the Soviet Naval Forces for service as an interim measure, to pend deployment
of the improved Tsiklon-B system, known as Parus. Between 1967 and 1978, there
were a total of 29 Tsiklon satellites launched for test and application, preliminarily
building the Soviet first generation of navigation satellite system.
Using the basic KAUR-1 bus (which was a drum covered with solar cells, with a
weighted mast on top for gravity-gradient stabilization, and an antenna hung off one
side near the bottom), the Parus satellite was a 2.0-m-diameter cylindrical spacecraft
4 Navigations from Ground to Space
inclinations of 90° and the periods of 106 min, and each satellite transmits navigation signals at two central frequencies of 400 MHz and 150 MHz, respectively.
The control segment is a ground network of tracking, measuring and controlling the
satellites, composed of the ground stations with known position coordinates. Its tasks
are to track each Transit satellite and measure its Doppler shift counts, estimate and
predict the satellite’s orbit and time parameters, and inject navigation message to
each satellite twice a day with the uplinks. The user segment consists of a variety of
the Doppler receivers, each of which measures the Transit satellite Doppler counts
in a given time interval and establishes the measurement equations, and then the
location coordinates of user receivers can be estimated by using the method of least
squares. The orbits of the Transit satellites were designed to pass over the North and
South Poles of the Earth, and evenly distributed on the equator. One Transit satellite
at least can always be observed at any site in the world for a given time, and the site’s
coordinates can be determined. The time interval between twice positioning is several
hours near the equator, 1−2 h in the middle latitude and less than 1 h in the polar
regions of the Earth. The goal of building the Transit system is to regularly calibrate
the inertial navigation system on board of the Polaris submarine, so the positioning
interval, even with several hours, can also meet the system-built requirements. In
other words, the Transit system is not applied to the real-time navigation for highly
dynamic users. At any site, by measuring the Doppler shift counts of a single pass
of a Transit satellite and using the dual-frequency signals to weaken the ionosphere
delays, the navigation parameters can be obtained with the positioning accuracy of
200 m and the timing accuracy of 50 microseconds [8].
In 1960s, the Soviet Union began to develop the navigation satellite system, called
Tsiklon, in order to provide the Soviet ballistic missile submarines with accurate
position fixed. As early as 1962, the draft project for a Tsiklon experiment satellite
was completed, using the Doppler navigation method, and the satellite would be
placed in 800−1000 km altitude orbits, but its development was prolonged due to
software problems and lack of accurate geodetic data. Until May 1967, the first
Tsiklon satellite Cosmos-158 with a weight of 750 kg was launched into the orbit,
with an apogee of 812 km, a perigee of 731 km and an inclination of 74 degrees to
carry out the flight tests. Subsequently, the first positioning test was conducted with a
Project-680 vessel of the Black Sea fleets, demonstrating a position error of 3 km, an
intolerable test result. In 1969, after improving the models of predicting the satellite’s
ephemerides and incorporating new information on the gravitational anomalies and
geoids of the Earth, an average position error reached 100 m over a 5-day period. On
the basis of further improving a mapping of the Earth’s gravitational anomalies, the
Tsiklon system’s tests had continued, and until 1972, the system was finally accepted
by the Soviet Naval Forces for service as an interim measure, to pend deployment
of the improved Tsiklon-B system, known as Parus. Between 1967 and 1978, there
were a total of 29 Tsiklon satellites launched for test and application, preliminarily
building the Soviet first generation of navigation satellite system.
Using the basic KAUR-1 bus (which was a drum covered with solar cells, with a
weighted mast on top for gravity-gradient stabilization, and an antenna hung off one
side near the bottom), the Parus satellite was a 2.0-m-diameter cylindrical spacecraft