US 10,591,591 B1 · Adaptive discovery and correction of phase alignment errors in monopulse antenna systems

Abstract

A mainlobe detection process can include a number of tests that are performed to define when the monopulse antenna system will transition from open loop scanning to closed loop scanning and then to tracking. A hybrid tracking technique is also provided which adaptively discovers and corrects for phase alignment error. Magnitude-only tracking can be performed initially to locate the nulls in the azimuth and elevation ratios and to identify the magnitudes of these ratios at these nulls. Phase tracking can be then performed. During phase tracking, phase corrections can be repeatedly applied to the azimuth and elevation difference channels to correct any phase error that may exist. During this process, the magnitudes of the ratios can be used to determine how the phase corrections should be adjusted. Once the hybrid tracking process is complete, the monopulse antenna system is properly phase-aligned and phase tracking will be correctly employed.

Claims21

Dependent claims

A method for performing tracking in a monopulse antenna system that provides tracking in one of an azimuth axis or an elevation axis or in both the azimuth axis and the elevation axis, the method comprising:

performing magnitude-only tracking;
during magnitude-only tracking, storing one or both of a first azimuth magnitude parameter that represents a magnitude of the azimuth ratio over a number of magnitude steering iterations or a first elevation magnitude parameter that represents a magnitude of the elevation ratio over the number of magnitude steering iterations, and also storing one or both of an azimuth direction indicator that represents a phase of the azimuth ratio over the number of magnitude steering iterations or an elevation direction indicator that represents a phase of the elevation ratio over the number of magnitude steering iterations;
after magnitude-only tracking has been performed for the number of magnitude steering iterations, comparing one or both of the azimuth direction indicator or the elevation direction indicator to a defined threshold;
and
upon determining that one or both of the azimuth direction indicator or the elevation direction indicator is below the defined threshold, commencing phase tracking.

2 more elements

A monopulse antenna system comprising:

a monopulse antenna comprising a number of monopulse antenna elements;
a comparator network that generates a sum channel, an azimuth difference channel, and an elevation difference channel from a signal received at the monopulse antenna;
and
a monopulse detector assembly that receives the sum channel, the azimuth difference channel, and the elevation difference channel from the comparator network and generates an azimuth ratio and an elevation ratio from the channels;
the monopulse detector assembly being configured to perform hybrid tracking by:
while performing magnitude-only tracking, storing a first azimuth magnitude parameter that represents a magnitude of the azimuth ratio over a number of magnitude steering iterations and a first elevation magnitude parameter that represents a magnitude of the elevation ratio over the number of magnitude steering iterations, and also storing an azimuth direction indicator that represents a phase of the azimuth ratio over the number of magnitude steering iterations and an elevation direction indicator that represents a phase of the elevation ratio over the number of magnitude steering iterations;
after magnitude-only tracking has been performed for the number of magnitude steering iterations, comparing the azimuth direction indicator and the elevation direction indicator to a defined threshold;
and
upon determining that the azimuth direction indicator and the elevation direction indicator are below the defined threshold, commencing phase tracking.

6 more elements

A method for detecting the mainlobe in a monopulse antenna system and then tracking on the mainlobe, the method comprising:

during open loop scanning, performing an initial power-level test to identify when a lobe has been located;
in response to the initial power-level test passing, commencing closed loop scanning;
during closed loop scanning, performing a track-lock test to identify when the mainlobe has been located;
and
in response to the track-lock test passing, commencing hybrid tracking in which magnitude-only tracking is initially performed and then phase tracking is performed, the hybrid tracking comprising:
commencing magnitude-only tracking;
during magnitude-only tracking, storing a first azimuth magnitude parameter that represents a magnitude of the azimuth ratio over a number of magnitude steering iterations and a first elevation magnitude parameter that represents a magnitude of the elevation ratio over the number of magnitude steering iterations, and also storing an azimuth direction indicator that represents a phase of the azimuth ratio over the number of magnitude steering iterations and an elevation direction indicator that represents a phase of the elevation ratio over the number of magnitude steering iterations;
after magnitude-only tracking has been performed for the number of magnitude steering iterations, comparing the azimuth phase parameter and the elevation phase parameter to a defined threshold;
and
upon determining that the azimuth direction indicator and the elevation direction indicator are below the defined threshold, commencing phase tracking.

7 more elements

Dependencies are inferred from the claim text.

Adaptive discovery and correction of phase alignment errors in monopulse antenna systems

Life of this patent

Adaptive discovery and correction of phase alignment errors in monopulse antenna systems

Life of this patent

Abstract

Claims21