Radio frequency arraying method for receivers
First Claim
1. A method for arraying a plurality of receiving systems coupled to one or more antennas for coherent frequency reception, each receiving system having a first IF mixer and a second IF mixer, comprising the steps ofcarrier frequency tracking in one receiving system utilizing a phase-lock loop to control the frequency of a first local oscillator for the first IF mixer thereof, and using the output of said first local oscillator as the local oscillator for the first IF mixer of each of the remaining systems,carrier phase tracking in each of said remaining receiving systems relative to said one receiving system at IF frequency using a constant reference frequency for the second IF mixer in said one receiving system, and in each remaining system using a phase-lock loop to control the frequency of a second local oscillator for the second IF mixer thereof, andsumming of the second IF signals in all of said remaining receiving systems with the second IF signal in said one receiving system.
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Abstract
A method and apparatus for increasing the signal-to-noise ratio of a receiving facility for coherent frequency reception by arraying receiving systems using separate antennas for each, or one antenna for all systems. One system is operated with a carrier tracking loop to provide a first local oscillator frequency for the first and all other systems arrayed, with individual tracking loops in all other systems operated at IF for tracking out any phase differences due to separate group delays using an adjustable phase shifter for a second reference (REF. 2) to compensate for different group delays in the antenna and low-noise amplifier of each of the other systems. The second IF output of all systems are summed into the first system. This technique may also be used when two systems are arrayed to an antenna designed for circular or linear polarization diversity reception to effectively provide the same signal-to-noise ratio for both polarized signal transmission channels that would result from matched polarization. An arrangement adapted to high rate telemetry reception is disclosed. With additional components, the same arrangement is adapted to provide low rate telemetry reception as well.
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Citations
20 Claims
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1. A method for arraying a plurality of receiving systems coupled to one or more antennas for coherent frequency reception, each receiving system having a first IF mixer and a second IF mixer, comprising the steps of
carrier frequency tracking in one receiving system utilizing a phase-lock loop to control the frequency of a first local oscillator for the first IF mixer thereof, and using the output of said first local oscillator as the local oscillator for the first IF mixer of each of the remaining systems, carrier phase tracking in each of said remaining receiving systems relative to said one receiving system at IF frequency using a constant reference frequency for the second IF mixer in said one receiving system, and in each remaining system using a phase-lock loop to control the frequency of a second local oscillator for the second IF mixer thereof, and summing of the second IF signals in all of said remaining receiving systems with the second IF signal in said one receiving system.
- 7. A method for increasing the sensitivity of a receiving facility for coherent radio frequency reception by arraying a plurality of receiving systems which receive a modulated carrier signal from the same or separate antennas, operating one of the arrayed systems as a master with a carrier tracking loop to provide to a first heterodyne mixer in each of said plurality of receiving systems a first local oscillator frequency used to produce a first IF signal in each system, operating each of said plurality of systems except the first with individual tracking loops at the first IF to provide a second local oscillator frequency to a second heterodyne mixer for producing a second IF signal in each system while the master receiving system is operated with a first fixed reference signal to be mixed with the first IF to produce the second IF, and using a separate adjustable phase shifter for adjustment of the second local oscillator frequency in each of the other systems arrayed to compensate for differences in group delay of the received signal through the receiving antenna and preamplifier coupling into the first mixer, thereby to provide second IF signals that are in phase, and summing the second IF signals of all systems with the second IF signal of the first system.
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11. A radio frequency receiving facility moving a plurality of receiving systems coupled to one or more antennas for coherent frequency reception, each receiving system having a first IF mixer and a second IF mixer, comprising:
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means for carrier frequency tracking in one receiving system utilizing a phase-lock loop to control the frequency of a first local oscillator for the first IF mixer thereof, means for using the output of said first local oscillator as the local oscillator for the first IF mixer of each of the remaining systems, means for carrier phase tracking in each of said remaining receiving systems relative to said one receiving system at IF frequency using a constant reference frequency for the second IF mixer in said one receiving system, and in each remaining system using a phase-lock loop to control the frequency of a second local oscillator for the second IF mixer thereof, and means for summing of the second IF signals in all of said remaining receiving systems with the second IF signal in said one receiving system. - View Dependent Claims (12, 13, 14, 15, 16)
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17. In a facility for coherent radio frequency reception, a plurality of receiving systems which receive a modulated carrier signal from the same or separate antennas, apparatus for combining said receiving systems to increase the sensitivity of said facility for coherent radio frequency reception, comprising
a carrier frequency tracking loop in one of said receiving systems to provide to a first heterodyne mixer in each of said plurality of receiving systems a first local oscillator frequency used to produce a first IF signal in each receiving systems, a separate carrier phase tracking loop in each of said one to provide a second local oscillator frequency signal to a second heterodyne mixer for producing a second IF signal in each receiving system in phase with a second IF signal in said one receiving system produced in a second heterodyne mixer thereof by beating with a fixed reference frequency signal, means for separately adjusting the phase of said second local oscillator frequency in each of said receiving systems except said one system to compensate for difference in group delay of the received signal relative to the group delay of the received signal in said one receiving system, and means for summing the second IF signals of all of said receiving systems with the second IF signal in said one receiving system.
Specification