Diversity receiver suitable for large scale integration

Claim 2

In a diversity receiver having a plurality of branches a diversity branch circuit comprising: means for receiving a signal containing transmitted information common to all branches and phase information distinctive to the individual branch, means for producing a pilot signal containing the distinctive phase information and being free of the transmitted information, means for temporarily combining with the received signal on each branch an acquisition signal common to all branches, means for slot filtering the pilot signal, the slot frequency being determined by the acquisition signal, and means for mixing a portion of the received signal with the slot filtered pilot signal to produce an output signal at a frequency common to and in-phase with the output signals of all of the other branches.

Claim 3

A diversity branch circuit as claimed in claim 1 wherein said means for slot filtering is a phase-locked loop and the acquisition signal swamps the input of the phase-locked loop to cause it to lock onto the determined slot frequency.

Claim 4

A diversity receiver comprising: a plurality of antenna elements, a plurality of branch circuits each having a branch signal derived from the reception of an exclusive one of the elements, each of said branch signals containing transmitted intelligence information received in common by all elements and a phase indication received exclusively by said one element, each branch circuit including mixing means for generating from the branch signal an intelligence-free signal containing the phase indication exclusive to said one element, means for narrowband filtering the intelligence-free signal, cophasing means for combining the branch signal and the filtered intelligence-free signal to yield an output signal at a prescribed output frequency common to all branches which is free of the phase indication, and means for temporarily swamping the branch signal in each branch with a relatively strong unmodulated signal common to all branches, said unmodulated signal being selected so that said means for narrowband filtering locks on to the intelligence-free signal, and means for linearly combining the output signal of all branches.

Claim 5

A diversity receiver comprising: a plurality of antenna elements, a plurality of branch circuits each having a branch signal derived from the reception of an exclusive one of the elements, each of said branch signals containing transmitted intelligence information received in common by all elements and a phase indication received exclusively by said one element, each branch circuit including mixing means for generating from the branch signal an intelligence-free signal containing the phase indication exclusive to said one element, means for narrowband filtering the intelligence-free signal, cophasing means for combining the branch signal and the filtered intelligence-free signal to yield an output signal at a prescribed output frequency common to all branches which is free of the phase indication, and means for temporarily swamping the branch signal in each branch with a relatively strong unmodulated signal common to all branches, said unmodulated signal being selected so that said means for narrowband filtering locks on to the intelligence-free signal, and means for linearly combining the output signal of all branches.

Claim 6

A diversity receiver as claimed in claim 3 wherein said filtering means includes a phase-locked loop which acts as a slot filter and wherein the means for temporarily swamping the branch signal causes the phase-locked loop to lock on to and pass a narrowband signal having a frequency at the difference between the branch signal frequency and the prescribed output frequency.

Claim 7

A diversity receiver as claimed in claim 4 wherein the phase-locked loop of each branch includes a loop mixer, lowpass filter and voltage-controlled oscillator connected in series, and a feedback path from the output of the voltage controlled oscillator to the input of the loop mixer, and wherein the inputs of the voltage controlled oscillator in each branch are interconnected by a dc path and ac isolated from each other.

Claim 8

A diversity receiver as claimed in claim 4 wherein each of said branch circuits is composed entirely of integrated circuitry.

Claim 9

A diversity receiver as claimed in claim 4 wherein each of said branch circuits includes feedback means for feeding back a signal at the prescribed output frequency from the output of the linear combining means to the input of the phase-locked loop.

Claim 10

A diversity receiver as claimed in claim 7 wherein said receiver further includes an acquisition oscillator common to all branches aNd wherein said means for temporarily swamping the input signal includes conductive means for temporarily connecting said oscillator output to the input of the phase-locked loop in lieu of said feedback signal.

Claim 11

A diversity receiver as claimed in claim 4 wherein said receiver further includes an acquisition oscillator common to all branches and wherein said means for temporarily swamping the branch signal includes conductive means for connecting said oscillator to the branch signal path, said conductive means including switching means for open circuiting the connection after acquisition of lock-on.

Claim 12

A diversity receiver as claimed in claim 9 wherein said switching means provides isolation between the branch circuits under open circuit conditions.

Claim 13

A diversity receiver as claimed in claim 9 wherein each of said branch circuits includes an IF mixer which converts the reception of said one element to a branch signal at an intermediate frequency and wherein said conductive means applies said oscillator output to the intermediate frequency signal.

Claim 14

A diversity receiver as claimed in claim 9 wherein each of said branch circuits includes an IF mixer which converts the reception of said one element to a branch signal at an intermediate frequency and wherein said conductive means connects said oscillator and said IF mixer.

Claim 15

A diversity receiver comprising, a plurality of branch circuits, an oscillator for producing a signal at a preselected frequency, switching means for temporarily connecting the preselected signal to each of the branches, and means for combining the outputs from all of said branches, each of said branches including cophasing means for producing in-phase outputs from all branches, a phase-locked loop for maintaining the frequency of the in-phase outputs within a fixed frequency range, and means for establishing the fixed range in response to the preselected frequency signal.

Claim 16

A diversity receiver comprising, a plurality of branch circuits, an oscillator for producing a signal at a preselected frequency, switching means for temporarily connecting the preselected signal to each of the branches, and means for combining the outputs from all of said branches, each of said branches including cophasing means for producing in-phase outputs from all branches, a phase-locked loop for maintaining the frequency of the in-phase outputs within a fixed frequency range, and means for establishing the fixed range in response to the preselected frequency signal.

Claim 17

A diversity receiver comprising: a plurality of antenna elements for receiving on each element a signal containing transmitted intelligence information common to all elements and a phase indication exclusive to each element, a plurality of branch circuits each associated exclusively with one of said antenna elements, each branch circuit including means for generating from the reception of said one element an intelligence-free signal containing the phase indication exclusive to said one element, means for narrowband filtering the intelligence-free signal, cophasing means for combining the reception and the filtered intelligence-free signal to yield an output signal at an output frequency common to all branches and in-phase with all other output signals, and means for linearly combining the output signals of all branches, characterized in that said receiver further includes means for temporarily swamping the reception in each branch with a relatively strong unmodulated signal common to all branches to cause the filtering means to lock on to the frequency of the intelligence-free signal.

Claim 18

A diversity receiver comprising: a plurality of antenna elements for receiving on each element a signal containing transmitted intelligence information common to all elements and a phase indication exclusive to each element, a plurality of branch circuits each associated exclusively with one of said antenna elements, each branch circuit including means for generating from the reception of said one element an intelligence-free signal containing the phase indication exclusive to said one element, means for narrowband filtering the intelligence-free signal, cophasing means for combining the reception and the filtered intelligence-free signal to yield an output signal at an output frequency common to all branches and in-phase with all other output signals, and means for linearly combining the output signals of all branches, characterized in that said receiver further includes means for temporarily swamping the reception in each branch with a relatively strong unmodulated signal common to all branches to cause the filtering means to lock on to the frequency of the intelligence-free signal.

Claim 19

A diversity receiver as claimed in claim 14 wherein each of said branch circuits is composed entirely of integrated circuitry.

Claim 20

A circuit comprising a phase-locked loop, means for applying an input signal to the phase-locked loop, an acquisition oscillator for producing an unmodulated acquisition signal, switching means for applying the acquisition signal to said phase-locked loop, said acquisition signal having a frequency and amplitude selected to cause the phase-locked loop to lock on to a prescribed frequency independent of the input signal, and said switching means being operable to remove said acquisition signal upon acquisition of lock-on to said prescribed frequency.

Claim 21

A circuit comprising a phase-locked loop, means for applying an input signal to the phase-locked loop, an acquisition oscillator for producing an unmodulated acquisition signal, switching means for applying the acquisition signal to said phase-locked loop, said acquisition signal having a frequency and amplitude selected to cause the phase-locked loop to lock on to a prescribed frequency independent of the input signal, and said switching means being operable to remove said acquisition signal upon acquisition of lock-on to said prescribed frequency.