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16 Hyperbolic Radio Navigation Systems
a phase difference ϕ = 2π into (16.8) formula, we obtain a maximum value of
unambiguous (single-valued) measured difference of distances:
D amb = λ 0 .
(16.10)
Readings of phase discriminator each time after achieving of distances difference,
equals D amb , will be repeated. Position lines, for which phase difference between
signals of two ground-based stations equals to 2π value (or, put it in another way,
equals to zero), discriminate the system operating area into zones of single-valued
read out, so-called tracks. With distance from the system base, the track width
increases. At the base, it has a minimum width. Within one track, phase measurements
turn to be single-valued.
Read-out ambiguity elimination in phased HRNS is carried out via reading of
full cycles of phase difference increment of received oscillations, or by creating of
additional grids of position lines at use of auxiliary pattern (comparison) frequency.
Stations operate at different frequencies, and phase difference measurement is carried
out at reduced comparison frequency. This is caused by the fact that at HRNS operation on one frequency, the interference of fields takes place, creating a disturbed sum
signal at receiving point.
Use of advantages of pulsed and phased HRNS has lead to development of pulsephase HRNS. The relative radio signal delay in pulse-phase HRNS is defined based
on information on simultaneously measured navigational parameters. t and ϕ.
To this date, several types of HRNS, relating to phased and pulse-phase HRNS,
are still in service.
The phased HRNS are introduced by the Russian “Marshrut” HRNS-20 system.
“Marshrut” phased HRNS (another system designation is “Alfa”) has been developed
simultaneously with the US Omega-phased HRNS (withdrawn from service in 1997)
and brought into service in 1972. The system operational range is up to 10,000 km
from a master station. Position finding accuracy is 2.5…7 km. The system has been
updated by 1999 at position finding accuracy level of not worse than 1.2…1.5 km.
Nowadays, the pulse-phase HRNS are represented by the Russian “Chaika” and
the US “Loran-C.”
HRNS “Chaika” (another designation is “Tropik”) includes several chains of
ground-based station of HRNS-3, HRNS-4, HRNS-5, HRNS-10 types (mobile
version). Total area of operating zones of all “Chaika” HRNS chains is about
20 million of square kilometers. The system operational range is up to 20,000 km,
determination accuracy of an object hyperbolic coordinates comprises about 700 m.
Stations’ operating frequency of the system is 100 kHz. Nowadays, “Chaika” pulsephase HRNS is considered as an effective supplement for GLONASS SRNS, ensuring
an increase of access and integrity of the system in favor of commercial customers.
HRNS “Loran-C” (LOng RAnge Navigation)—is the US-developed groundbased radio navigation system introduced into service by the end of 1950. Loran-C
system operates at 100 kHz frequency. Estimated accuracy of the system comprises
150–200 km at distance up to 1500 km. The system operational range is up to
16 Hyperbolic Radio Navigation Systems
a phase difference ϕ = 2π into (16.8) formula, we obtain a maximum value of
unambiguous (single-valued) measured difference of distances:
D amb = λ 0 .
(16.10)
Readings of phase discriminator each time after achieving of distances difference,
equals D amb , will be repeated. Position lines, for which phase difference between
signals of two ground-based stations equals to 2π value (or, put it in another way,
equals to zero), discriminate the system operating area into zones of single-valued
read out, so-called tracks. With distance from the system base, the track width
increases. At the base, it has a minimum width. Within one track, phase measurements
turn to be single-valued.
Read-out ambiguity elimination in phased HRNS is carried out via reading of
full cycles of phase difference increment of received oscillations, or by creating of
additional grids of position lines at use of auxiliary pattern (comparison) frequency.
Stations operate at different frequencies, and phase difference measurement is carried
out at reduced comparison frequency. This is caused by the fact that at HRNS operation on one frequency, the interference of fields takes place, creating a disturbed sum
signal at receiving point.
Use of advantages of pulsed and phased HRNS has lead to development of pulsephase HRNS. The relative radio signal delay in pulse-phase HRNS is defined based
on information on simultaneously measured navigational parameters. t and ϕ.
To this date, several types of HRNS, relating to phased and pulse-phase HRNS,
are still in service.
The phased HRNS are introduced by the Russian “Marshrut” HRNS-20 system.
“Marshrut” phased HRNS (another system designation is “Alfa”) has been developed
simultaneously with the US Omega-phased HRNS (withdrawn from service in 1997)
and brought into service in 1972. The system operational range is up to 10,000 km
from a master station. Position finding accuracy is 2.5…7 km. The system has been
updated by 1999 at position finding accuracy level of not worse than 1.2…1.5 km.
Nowadays, the pulse-phase HRNS are represented by the Russian “Chaika” and
the US “Loran-C.”
HRNS “Chaika” (another designation is “Tropik”) includes several chains of
ground-based station of HRNS-3, HRNS-4, HRNS-5, HRNS-10 types (mobile
version). Total area of operating zones of all “Chaika” HRNS chains is about
20 million of square kilometers. The system operational range is up to 20,000 km,
determination accuracy of an object hyperbolic coordinates comprises about 700 m.
Stations’ operating frequency of the system is 100 kHz. Nowadays, “Chaika” pulsephase HRNS is considered as an effective supplement for GLONASS SRNS, ensuring
an increase of access and integrity of the system in favor of commercial customers.
HRNS “Loran-C” (LOng RAnge Navigation)—is the US-developed groundbased radio navigation system introduced into service by the end of 1950. Loran-C
system operates at 100 kHz frequency. Estimated accuracy of the system comprises
150–200 km at distance up to 1500 km. The system operational range is up to