250
14 Pseudo-Ranging Radio Navigation Systems
is, in latitude and longitude; VDOP—(Vertical DOP)—characterizes the accuracy of
determining the height. By analogy, the concept of TDOP (Time DOP) is introduced
to characterize the accuracy of time determination by an onboard receiver.
It should be remembered that all types of DOPs characterize an accuracy in relative
values, that is, they are dimensionless. If the mean-square error of measuring the
pseudo-range σ D was known precisely under these specific conditions, then it would
be possible to quantitatively determine in absolute values (in meters) the root meansquare error in determining the coordinates σ R .
σ R = DOPσ d .
(14.7)
Depending on what kind of error you need to determine (the spatial position of
the aircraft, in the horizontal plane or in height), PDOP, HDOP VDOP should be
used as DOP in this formula.
Most navigation receivers indicate the current DOP value, which allows the user
to judge the accuracy of the navigation definitions. This is especially important for
navigation in areas where certain requirements for its accuracy are established.
Interference. The operating experience of the SRNS shows that the signals emitted
by the NSV are subject to various types of interference. Unintentional man-made
interference includes emissions from radio transmitters that can generate signals
with unwanted L-band power levels. Artificial unintentional interference is created
by radio lines, harmonics of television channels, request signals of short-range navigation systems, harmonics of existing VHF radio stations, the Globalstar satellite
communication system, radar stations of air traffic control systems. Portable electronic devices used by passengers on board an AV (computers, mobile phones) can
also interfere with the SRNS, as well as other onboard radio navigation systems.
Another factor leading to errors in pseudo-range measurement is the noises of the
object onboard receiver itself.
We have examined only the main factors affecting the SRNS measurements accuracy. Modern equipment of SRNS users is multichannel and uses methods of optimal
signal processing. As shown by experimental studies and the practice of using the
SRNS, the global navigation of objects of sea and air transport can be provided with
maximum errors in determining the spatial coordinates of an object of 30–60 m on
a plane and 50–100 m in height.
SRNS are constantly being upgraded in order to provide higher accuracy. In
addition, various options for functional updates to the SRNS are being developed,
which will be discussed below.
14.3 Satellite Radio Navigation Systems
SRNS are autonomous medium-orbit satellite systems that allow with a high accuracy
to determine the spatial coordinates of moving and stationary objects on the Earth’s
surface and in near-earth space, as well as to carry out accurate time coordination. The
14 Pseudo-Ranging Radio Navigation Systems
is, in latitude and longitude; VDOP—(Vertical DOP)—characterizes the accuracy of
determining the height. By analogy, the concept of TDOP (Time DOP) is introduced
to characterize the accuracy of time determination by an onboard receiver.
It should be remembered that all types of DOPs characterize an accuracy in relative
values, that is, they are dimensionless. If the mean-square error of measuring the
pseudo-range σ D was known precisely under these specific conditions, then it would
be possible to quantitatively determine in absolute values (in meters) the root meansquare error in determining the coordinates σ R .
σ R = DOPσ d .
(14.7)
Depending on what kind of error you need to determine (the spatial position of
the aircraft, in the horizontal plane or in height), PDOP, HDOP VDOP should be
used as DOP in this formula.
Most navigation receivers indicate the current DOP value, which allows the user
to judge the accuracy of the navigation definitions. This is especially important for
navigation in areas where certain requirements for its accuracy are established.
Interference. The operating experience of the SRNS shows that the signals emitted
by the NSV are subject to various types of interference. Unintentional man-made
interference includes emissions from radio transmitters that can generate signals
with unwanted L-band power levels. Artificial unintentional interference is created
by radio lines, harmonics of television channels, request signals of short-range navigation systems, harmonics of existing VHF radio stations, the Globalstar satellite
communication system, radar stations of air traffic control systems. Portable electronic devices used by passengers on board an AV (computers, mobile phones) can
also interfere with the SRNS, as well as other onboard radio navigation systems.
Another factor leading to errors in pseudo-range measurement is the noises of the
object onboard receiver itself.
We have examined only the main factors affecting the SRNS measurements accuracy. Modern equipment of SRNS users is multichannel and uses methods of optimal
signal processing. As shown by experimental studies and the practice of using the
SRNS, the global navigation of objects of sea and air transport can be provided with
maximum errors in determining the spatial coordinates of an object of 30–60 m on
a plane and 50–100 m in height.
SRNS are constantly being upgraded in order to provide higher accuracy. In
addition, various options for functional updates to the SRNS are being developed,
which will be discussed below.
14.3 Satellite Radio Navigation Systems
SRNS are autonomous medium-orbit satellite systems that allow with a high accuracy
to determine the spatial coordinates of moving and stationary objects on the Earth’s
surface and in near-earth space, as well as to carry out accurate time coordination. The