System of directional antennas with means for reducing flutter
First Claim
Patent Images
1. A method of reducing flutter in received radio frequency signal transmissions comprising the steps of:
- a. providing first and second antenna devices having selectable directional receiving patterns;
b. fixing the receiving pattern of one of the directional receiving antennas to receive a selected signal while sweeping the receiving pattern of the other directional receiving antenna to produce a second signal;
c. selecting the antenna pattern that is fixed at any particular time as the one producing the stronger signal; and
d. combining the received signals to produce an output.
1 Assignment
0 Petitions
Accused Products
Abstract
Flutter in received radio signals at and above 150 MHz is reduced by a system having a plurality of directional antennas with receiving patterns that can be caused to rotate to sweep in azimuth. The antenna that receives the strongest signal is stopped from sweeping until another antenna receives a stronger signal, at which time it is stopped from sweeping and the antenna that was stopped is swept. Signals from all antennas are combined in a maximal-ratio diversity receiver to provide a combination of the signals that is additive regardless of their relative phase.
32 Citations
17 Claims
-
1. A method of reducing flutter in received radio frequency signal transmissions comprising the steps of:
-
a. providing first and second antenna devices having selectable directional receiving patterns; b. fixing the receiving pattern of one of the directional receiving antennas to receive a selected signal while sweeping the receiving pattern of the other directional receiving antenna to produce a second signal; c. selecting the antenna pattern that is fixed at any particular time as the one producing the stronger signal; and d. combining the received signals to produce an output. - View Dependent Claims (2, 3, 4)
-
-
5. A method of reducing flutter in received radio frequency signal transmissions comprising the steps of:
-
a. providing first and second antenna devices having selectable directional receiving patterns; b. fixing the receiving pattern of one of the directional receiving antennas to receive a selected signal while sweeping the receiving pattern of the other directional receiving antenna to produce a second signal; c. selecting the antenna pattern that is fixed at any particular time as the one producing the stronger IF signal; d. mixing each of the received signals from the antennas with a signal from a common local oscillator to produce first and second IF signals; and e. combining the first and second IF signals to produce an output. - View Dependent Claims (6, 7, 8)
-
-
9. A method of reducing flutter in received radio transmissions comprising the steps of:
-
a. sweeping a receiving pattern of a first directional receiving antenna in azimuth to receive a first signal; b. fixing a receiving pattern of a second directional receiving antenna on a second signal that is stronger than the first signal; c. selecting the stronger of the first and second signals; d. fixing the receiving pattern of the directional receiving antenna that produces the stronger signal; e. sweeping the receiving pattern of the receiving antenna that produces a weaker signal; f. mixing the first signal with a signal from a local oscillator to produce a first IF signal; g. mixing the second signal with the signal from the local oscillator to produce a second IF signal; and h. combining the first and second IF signals at a maximal-ratio diversity receiver to produce an output. - View Dependent Claims (10)
-
-
11. A method of reducing flutter in received radio transmissions comprising the steps of:
-
a. sweeping a receiving pattern of a first directional receiving antenna in azimuth to receive a first signal; b. fixing a receiving pattern of a second directional receiving antenna on a second signal that is stronger than the first signal; c. mixing the first signal from the first antenna with a signal from a local oscillator to produce a first IF signal; d. mixing the second signal from the second antenna with the signal from the local oscillator to produce a second IF signal; e. selecting the stronger of the first and second IF signals; f. fixing the receiving pattern of the directional receiving antenna that produces the stronger IF signal; g. sweeping the receiving pattern of the receiving antenna that produces a weaker IF signal; h. applying the first and second signals to a maximal-ratio diversity receiver to produce an output; i. detecting the output of the maximal-ratio diversity receiver to extract a modulating signal; and j. converting the modulating signal to usable form.
-
-
12. An apparatus for minimizing flutter in receiving radio signals, the apparatus comprising:
-
a. a first directional receiving antenna having a steerable receiving pattern; b. first means connected to the first antenna for rotating in azimuth the steerable receiving pattern of the first antenna; c. a second directional receiving antenna having a steerable receiving pattern; d. second steering means connected to the second antenna for rotating in azimuth the steerable receiving pattern of the second antenna; e. a scan controller connected to the first and second steering means to control steering of the first and second steering antennas; f. a maximal-ratio diversity receiver connected to the first and second antennas to receive and combine the signals from the first and second antennas and produce a diversity output signal; and g. a detector and amplifier connected to the maximal-ratio diversity receiver to receive the diversity signal and generate from it a usable signal. - View Dependent Claims (13, 14, 15, 17)
-
-
16. An apparatus for minimizing flutter in receiving radio signals, the apparatus comprising:
-
a. a first directional receiving antenna having a steerable receiving pattern; b. first means connected to the first antenna for rotating in azimuth the steerable receiving pattern of the first antenna; c. a first front end including a first mixer, connected to the first antenna to receive an RF radio signal therefrom; d. a second directional receiving antenna having a steerable receiving pattern; e. second steering means connected to the second antenna for rotating the steerable receiving pattern; f. a second front end including a second mixer connected to the second receiving antenna to receive an RF signal therefrom; g. a local oscillator connected to the first and second front end to produce respectively a first and a second IF signal therefrom; h. a first IF amplifier connected to the first front end to amplify the first IF signal therefrom; i. a second IF amplifier connected to the second front end to amplify the second IF signal therefrom; j. a scan controller connected to the first and second IF amplifiers and to the first and second steering means to receive IF signals from the first and second IF amplifiers and control steering of the first and second steering means; k. a maximal-ratio diversity receiver connected to the first and second IF amplifiers to receive and combine the first and second IF signals and produce a diversity output signal; l. a detector and audio amplifier connected to the maximal-ratio diversity receiver to receive the diversity signal and generate from it an audio signal; and m. means for converting the audio signal to usable form.
-
Specification