Method and apparatus for reducing multipath distortion in a television signal
View Patent ↗The disadvantages associated with the prior art are overcome by a method and apparatus for reducing multipath distortion in a television signal. Specifically, a plurality of antenna elements receive spatially unique replicas of a desired television signal. The spatially unique replicas are coupled to an adaptive combiner, which generates a spatially combined signal to be coupled to a television receiver. The adaptive combiner forms a weighted summation of the spatially unique replicas, which effectively places spatial nulls in the direction of the multipath interference. The weighting information is provided by an adaptive controller that uses intelligence from a multipath processor located within the apparatus. The intelligence may take the form of a figure of merit derived from the combiner output, or from processing preformed on the input signals themselves.
1. An apparatus for reducing multipath distortion in a television signal, which comprises:
a plurality of antenna elements for receiving the television signal, wherein each of said plurality of antenna elements receives a respective one of a plurality of spatially unique signals, each of said plurality of spatially unique signals being a different replica of the television signal;
an adaptive combiner, coupled to said plurality of antenna elements, for generating a weighted spatially combined signal; and
a receiver, coupled to said adaptive combiner, for demodulating said weighted spatially combined signal.
2. The apparatus of claim 1 wherein said plurality of antenna elements comprises a loop antenna having a plurality of feed ports, each of said plurality of feed ports being disposed around the perimeter of said loop antenna so as to receive a respective one of said plurality of spatially unique signals.
3. The apparatus of claim 1 wherein said adaptive combiner comprises:
a plurality of tuning modules, each of said tuning modules having a tuner and a weight for selecting a respective one of said plurality of spatially unique signals and generating a weighted spatially unique signal;
a summer, coupled to said weight of each of said plurality of tuning modules, for combining each weighted spatially unique signal to generate said spatially combined signal;
a multipath processor, coupled to said summer, for generating a figure of merit; and
an adaptive controller, coupled to said multi path processor and said weight of each of said plurality of tuning modules, wherein said adaptive controller controls the value of each weight using an adaptive algorithm having said figure of merit as input.
4. The apparatus of claim 3 wherein said adaptive algorithm comprises a cross-correlation algorithm.
5. The method of claim 3 wherein said adaptive controller uses a manual user selection, stored in a memory.
6. A loop antenna comprising:
a plurality of conductive strips arranged in a circular pattern, where each strip comprises at least one narrowed portion;
a feed point connected to said at least one narrowed portion of each strip;
a signal coupler for connecting adjacent feed points and thereby coupling signals from said plurality of conductive strips.
7. The loop antenna of claim 6 wherein said signal coupler comprises:
a coaxial cable having a shield coupled to a first conductive strip and a center conductor spanning the gap and coupled to a dummy coaxial cable formed on a second conductive strip.
8. The loop antenna of claim 6 wherein said signal coupler comprises:
a impedance matching transformer.
9. The loop antenna of claim 6 wherein said plurality of conductive strips are formed upon a circular substrate.
10. The loop antenna of claim 6 wherein each of said conductive strips in said plurality of conductive strips forms a Vivaldi antenna element.