Communications: directive radio wave systems and devices (e.g. – Directive – Including a satellite
Patent
1996-10-09
1998-11-03
Blum, Theodore M.
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a satellite
H04B 7185, G01S 502
Patent
active
058315756
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the priority of German applications P 44 12 336.1 filed Apr. 2, 1994 and 195 08 208.7 filed Mar. 8, 1995.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a satellite navigation method as defined in the preamble to claim 1.
The invention can be used particularly in the navigation of aircraft during landing.
The evaluation of suitable satellite signals is possible for navigation, particularly three-dimensional navigation. Such satellites are combined to form GPS (Global Positioning System) and GLONASS (GLobal Orbiting NAvigation Satellite System) navigation systems. GPS and GLONASS form GNSS (the Global Satellite Navigation System). The signals emitted by these satellites can be evaluated in different ways as a function of the required precision. One type of satellite navigation employs the evaluation of the code-phase or carrier-phase measurements of a GNSS user receiver that is installed on board a vehicle, for example an aircraft, whose position is supposed to be determined. The differential function (DGNSS) of GNSS is used to increase the navigation precision. In this instance, a second receiver, called reference receiver, is used at a known position in addition to the user receiver. The reference receiver determines measuring errors based on the known antenna position, and corrects the measurements of the user receiver.
In high-precision types of navigation, for example automatic aircraft landings, for safety reasons precision must be within the meter or even decimeter range. For example, from the microwave landing system (MLS), the has derived precision requirements (95%) for navigation sensors for precision landings using GNSS under the CAT I/II/III visual conditions of the International Civil Aviation Organisation (ICAO); these requirements are shown below in Table 1.
______________________________________ Horizontal Vertical
DH PFE CMN PFE CMN
______________________________________
CAT I 200 ft .+-.5.1 m
.+-.4.1 m
.+-.2.4 m
.+-.1.2 m
CAT II 100 ft .+-.4.4 m
.+-.3.5 m
.+-.1.2 m
.+-.0.6 m
CAT III 50 ft .+-.4.0 m
.+-.3.2 m
.+-.1.2 m
.+-.0.6 m
______________________________________
Feet (ft) are the standard unit of measurement in air travel; the abbreviations stand for the following:
In the DGNSS method (or DGPS method for GPS), errors that occur during measurements made with GNSS receivers, for example satellite clock errors, satellite path model errors, atmospheric errors and the influence of the earth's rotation, can be reduced by the differential function. Other errors, however, such as noise, influences of multiple-path propagation and dynamic influences, are uncorrelated between measurements by user receivers and reference receivers. These errors cannot be reduced by forming a difference.
In code measurements, the interfering influences of noise and dynamics on the determination of position are typically within the meter range. The interfering influences of multiple paths in code measurements can even cause a navigation error greater than 100 m when strong multiple-path reflections take place. The uncorrelated errors in the carrier-phase measurements, in contrast, range only from millimeters and centimeters, and are significantly smaller in comparison to corresponding errors in code measurements. In contrast to code measurement, however, carrier-phase measurement initially has an ambiguity that is associated with the number of wavelengths on the path of the signal transmission from a satellite to a (user and or reference) receiver.
2. Description of the Related Art
A known method that combines the complementary procedures of code measurement and phase measurement under the name "carrier-smoothed code" Proceedings:
Third International Symposium on Satellite Doppler Positioning, Las Cruces, February 1982, Volume 2, pages 1213-1231! can reduce the influence of code noise on the navigation error to the centimeter range. In this method, the receiver dynamics are determin
REFERENCES:
patent: 5072227 (1991-12-01), Hatch
patent: 5359332 (1994-10-01), Allison et al.
patent: 5477458 (1995-12-01), Loomis
B. W. Remondi: "Global Position System carrier phase: description and use"; In: Bulletin Geodesique, 1985, France, vol. 59, No. 4, pp. 361-377.
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G.L. Mader: "Dynamic Positioning Using GPS Carrier Phase Measurements", manuscripta geodaetica, Springer-Verlag 1986, pp. 272-277.
X. Gu: "DGPS Positioning Using Carrier Phase for Precision Navigation". IEEE 1994--Symposium Las Vegas/Nevada, Apr. 11-15, 1994, pp. 410-417.
H.Z. Abidin: "On-the-Fly Ambiguity Resolution". GPS World, Apr. 1994, pp. 40-50.
B. Remondi: "Pseudo-kinematic GPS Results Using the Ambiguity Function Method". In: Navigation: Journal of the Institute of Navigation, vol. 38, No. 1, Spring 1991, pp. 17-36.
Blum Theodore M.
NFS-Navigations- und Flugfuehrungs-Systeme GmbH
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