Correcting errors in crossfeed radar systems
AssigneeSiemens-Albis Aktiengesellschaft
InventorAlbert Schenkel
Life of this patent
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Abstract
A method for correction errors in radar systems that operate using a crossfeed principle (CFR), in which echo signals are directly received from flying objects, such as an aircraft. In particular, the present invention is used in connection with low-flying objects, in which radar signals are indirectly reflected from the surface of the earth to an antenna of the radar system. Correction terms are determined and weighted, using correction factors, so as to improve the capability of the crossfeed radar system to accurately determine the exact elevation of the flying object. The correction factors that are used to improve the accuracy of the radar system are based upon sea state numbers, or Beaufort numbers, which vary in relation to the shape and/or structure of the reflecting surface.
Claims26
A method for improving the accuracy of radar equipment operating in accordance with a crossfeed principle, in which echo signals are directly received from flying objects and indirectly received from reflections from a surface of the earth, comprising the steps of:
- weighting a first correction term with a first correction factor;
- and
- weighting a second correction term with a second correction factor, in which the second correction factor corresponds with a value selected for the first correction factor.
A method for improving the accuracy of radar equipment operating in accordance with a crossfeed principle, in which echo signals are directly received from flying objects and indirectly received from reflections from a surface of the earth, comprising the step of:
- weighting a correction term with a correction factor that is a function of a characteristic of the reflecting surface of the earth, comprising the steps of:
- weighting a first correction term with a first correction factor;
- and
- weighting a second correction term with a second correction factor by setting the second correction factor to correspond with a value selected for the first correction factor.
A method for improving the accuracy of radar equipment operating in accordance with a crossfeed principle, comprising the steps of:
- receiving echo signals that are directly reflected from a flying object;
- receiving echo signals that are indirectly reflected from a surface of the earth;
- and
- calculating a corrected elevation angle error signal F.sub.Ekorr according to the following equation:
- R.sub.Ekorr (W.sub.eE)=EEP+k1.multidot.FD1+k2.multidot.FD2
- where w.sub.dE comprises an angle axis of an antenna of the radar equipment;
- EEP comprises an in-phase portion of a signal associated with the radar equipment;
- k1 comprises a first correction factor that weights a first correction term FD1;
- and k2 comprises a second correction factor that weights a second correction term FD2, the second correction factor being selected to correspond with a value selected for the first correction factor.
A method for use with a crossfeed radar system for accurately determining an elevation of a flying object, comprising the steps of:
- obtaining a plurality of indirectly reflected echo signals that bounce off of an irregular surface of a body towards an antenna of the radar system;
- determining an in-phase portion of a signal associated with the radar system;
- and
- modifying the in-phase signal portion with first and second correction factor values that weighted by respective first and second correction terms so as to determine a corrected elevation angle between the flying object and an antenna axis of the radar system, the value of the first and second correction factors being dependent upon the irregularity of the surface, the value of the second correction factor being selected to correspond to a value of the first correction factor.
A method for use with a crossfeed radar system for accurately determining an elevation of a flying object, comprising the steps of:
- obtaining a plurality of indirectly reflected echo signals that bounce off of an irregular surface of a body towards an antenna of the radar system;
- determining an in-phase portion of a signal associated with the radar system;
- and
- modifying the in-phase signal portion with a sea state number so as to determine a corrected elevation angle between the flying object and an antenna axis of the radar system, the value of the sea state number being dependent upon the irregularity of the surface according to the equation:
- E.sub.Ekorr (W.sub.eD)=EEP+k1.multidot.FD1+k2.multidot.FD2
- where F.sub.Ekorr comprises a corrected elevation angle error signal;
- w.sub.dE comprises an angle axis of an antenna of the radar equipment;
- EEP comprises the in-phase signal portion;
- k1 comprises a first correction factor that weights a first correction term FD1;
- and k2 comprises a second correction factor that weights a second correction term FD2 by setting the second correction factor to be equal to 0 when the second correction term is to be disregarded, and setting the second correction factor to correspond with a value selected for the first correction factor when the second correction term is used.
A method for use with a crossfeed radar system for accurately determining an elevation of a flying object, comprising the steps of:
- obtaining a plurality of indirectly reflected echo signals that bounce off of an irregular surface of a body towards an antenna of the radar system;
- determining an in-phase portion of a signal associated with the radar system;
- and
- modifying the in-phase signal portion with a correction factor value so as to determine a corrected elevation angle between the flying object and an antenna axis of the radar system, the value of the correction factor being dependent upon the irregularity of the surface according to the invention:
- E.sub.Ekorr (w.sub.dE)=EEP+k1.multidot.FD1+k2.multidot.FD2
- where F.sub.Ekorr comprises a corrected elevation angle error signal;
- w.sub.dE comprises an angle axis of an antenna of the radar equipment;
- EEP comprises the in-phase signal portion;
- k1 comprises a first correction factor that weights a first correction term FD1;
- and k2 comprises a second correction factor that weights a second correction term FD2 by setting the second correction factor to be equal to 0 when the second correction term is to be disregarded, and setting the second correction factor to correspond with a value selected for the first correction factor when the second correction term is used.
A method for improving the accuracy of monopulse radar equipment that operates in accordance with a crossfeed principle, in which echo signals are directly received from flying objects and indirectly received from reflections from a surface of the earth, comprising the steps of:
- weighting a first correction term with a first correction factor that is a function of a characteristic of the reflecting surface of the earth;
- and
- weighting a second correction term with a second correction factor, wherein the step of weighting the second correction term with a second correction factor comprises the step of setting the second correction factor to correspond with a value selected for the first correction factor.
Dependencies are inferred from the claim text.