Master-slave, tuned channels for simultaneous tracking of plural signals of different frequencies

Claim 2

In a communication system, the combination comprising: first and second phase-lock loops, each loop including a superheterodyne receiver having a local oscillator input and having an output; a reference oscillator having an output signal of a constant frequency having an output; a phase detector having one input connected from said reference oscillator output and another input connected from said receiver output, said phase detector having an output; a variable frequency oscillator for providing an output signal in accordance with the magnitude of an input signal thereto, said variable frequency oscillator having an input and an output; first means connected from the output of said variable frequency oscillator to said receiver local oscillator input; second means connected from said phase detector output to said variable frequency oscillator input for changing the frequency of the output signal of said variable frequency oscillator in a direction tending to reduce the output signal of said phase detector to zero; and third means actuated to change the frequency of the output signal of said second loop variable frequency oscillator in accordance with the frequency of the output signal of said first loop variable frequency oscillator.

Claim 3

The invention as defined in claim 1, wherein said third means includes comparator means to produce an output signal in accordance with the difference between the output signal frequencies of said variable frequency oscillators, and sensitivity means to reduce the gain of said second loop drive means when said comparator means output signal falls below a predetermined threshold value.

Claim 4

In a communication system, the combination comprising: first and second phase-lock loops, each loop including a superheterodyne receiver having a local oscillator input and having an output; a reference oscillator having an output signal of a constant frequency having an output; a phase detector having one input connected from said reference oscillator output and another input connected from said receiver output, said phase detector having an output; a variable frequency oscillator for providing an output signal in accordance with the magnitude of an input signal thereto, said variable frequency oscillator having an input and an output; control means connected from the output of said variable frequency oscillator to said receiver local oscillator input; drive means connected from said phase detector output to said variable frequency oscillator input for changing the frequency of the output signal of said variable frequency oscillator in a direction tending to reduce the output signal of said phase detector to zero; first means for producing a first loop acquisition signal at the output thereof when the difference between the frequencies of the output signals of said first loop receiver and said first loop reference oscillator falls below a predetermined threshold level; second means for producing a second loop acquisition signal when the difference between the frequencies of the output signals of said second loop receiver and said second loop reference oscillator falls below a predetermined threshold level; comparator means to produce a slaving signal at the output thereof in accordance with the difference between the frequencies of the output signals of said variable frequency oscillators; first and second circuits for connecting the output of said comparator means to said first loop drive means and to said second loop drive means, respectively, said first circuit being actuable through said first loop drive means to change the output signal frequency of said first loop variable frequency oscillator in a direction to reduce the difference between the output signal frequencies of said variable frequency oscillators toward zero, said second circuit being actuable through said second loop drive means to change the output signal frequency of said second loop variable frequency oscillator in a direction to reduce the difference between the output signal frequencies of said variable frequency oscillators toward zero; variable means connected to both of said drive means to produce a tuning output signal for tuning said variable frequency oscillators; a first mode control actuable when said first loop acquisition signal is produced to interrupt said tuning signal to said first loop drive means, and to interrupt said tuning signal to said second loop drive means while passing said slaving signal thereto; a second mode control actuable when said second loop acquisition signal is produced to interrupt said tuning signal to said second loop drive means, and to interrupt said tuning signal to said first loop drive means while passing said slaving signal thereto, said first control, when actuated, interrupting the slaving signal provided by said second control to said first loop drive means, said second control, when actuated, interrupting said slaving signal provided by said first control to said second loop drive means.

Claim 5

In a communication system, the combination comprising: first and second phase-lock loops, each loop including a superheterodyne receiver having a local oscillator input and having an output; a reference oscillator having an output signal of a constant frequency having an output; a phase detector having one input connected from said reference oscillator output and another input connected from said receiver output, said phase detector having an output; a variable frequency oscillator for providing an output signal in accordance with the magnitude of an input signal thereto, said variable frequency oscillator having an input and an output; control means connected from the output of said variable frequency oscillator to said receiver local oscillator input; drive means connected from said phase detector output to said variable frequency oscillator input for changing the frequency of the output signal of said variable frequency oscillator in a direction tending to reduce the output signal of said phase detector to zero; first means for producing a first loop acquisition signal at the output thereof when the difference between the frequencies of the output signals of said first loop receiver and said first loop reference oscillator falls below a predetermined threshold level; second means for producing a second loop acquisition signal when the difference between the frequencies of the output signals of said second loop receiver and said second loop reference oscillator falls below a predetermined threshold level; comparator means to produce a slaving signal at the output thereof in accordance with the difference between the frequencies of the output signals of said variable frequency oscillators; first and second circuits for connecting the output of said comparator means to said first loop drive means and to said second loop drive means, respectively, said first circuit being actuable through said first loop drive means to change the output signal frequency of said first loop variable frequency oscillator in a direction to reduce the difference between the output signal frequencies of said variable frequency oscillators toward zero, said second circuit being actuable through said second loop drive means to change the output signal frequency of said second loop variable frequency oscillator in a direction to reduce the difference between the output signal frequencies of said variable frequency oscillators toward zero; variable means connected to both of said drive means to produce a tuning output signal for tuning said variable frequency oscillators; a first mode control actuable when said first loop acquisition signal is produced to interrupt said tuning signal to said first loop drive means, and to interrupt said tuning signal to said second loop drive means while passing said slaving signal thereto; a second mode control actuable when said second loop acquisition signal is produced to interrupt said tuning signal to said second loop drive means, and to interrupt said tuning signal to said first loop drive means while passing said slaving signal thereto, said first control, when actuated, interrupting the slaving signal provided by said second control to said first loop drive means, said second control, when actuated, interrupting said slaving signal provided by said first control to said second loop drive means.

Claim 6

In a communication system, the combination comprising: first and second phase-lock loops, each loop including a superheterodyne receiver having a local oscillator input and having an output; a reference oscillator having an output signal of a constant frequency having an output; a phase detector having one input connected from said receiver output, said phase detector having an output; a variable frequency oscillator for providing an output signal in accordance with the magnitude of an input signal thereto, said variable frequency oscillator having an input and an output; control means connected from the output of said variable frequency oscillator to said receiver local oscillator input; drive means connected from said phase detector output to said variable frequency oscillator input for changing the frequency of the output signal of said variable frequency oscillator in a direction tending to reduce the output signal of said phase detector to zero; first means for producing a first loop acquisition signal at the output thereof when the difference between the frequencies of the output signals of said first loop receiver and said first loop reference oscillator falls below a predetermined threshold level; second means for producing a second loop acquisition signal when the difference between the frequencies of the output signals of said second loop receiver and said second loop reference oscillator falls below a predetermined threshold level; comparator means to produce a slaving signal at the output thereof in accordance with the difference between the frequencies of the output signals of said variable frequency oscillators; a tuning control having an output; first and second slaving relays, each of said first and second slaving relays being adapted to operate at least one single-pole, double-throw switch, said switch including a movable pole, a normally closed contact, and a normally open contact, said tuning control output being connected to each slaving relay normally closed contact, said comparator means output being connected to each slaving relay normally open contact; and first and second override relays each having a pair of normally closed contacts connected in series between said first and second slaving relay poles, respectively, to said first and second loop drive means, respectively, said first means being adapted to energize said first override relay and said second slaving relay when said first loop acquisition signal is produced, said second means being adapted to energize said second override relay and said first slaving relay when said second loop acquisition signal is produced.

Claim 7

In a communication system, the combination comprising: first and second phase-lock loops, each loop including a superheterodyne receiver having a local oscillator input and having an output; a reference oscillator having an output signal of a constant frequency having an output; a phase detector having one input connected from said receiver output, said phase detector having an output; a variable frequency oscillator for providing an output signal in accordance with the magnitude of an input signal thereto, said variable frequency oscillator having an input and an output; control means connected from the output of said variable frequency oscillator to said receiver local oscillator input; drive means connected from said phase detector output to said variable frequency oscillator input for changing the frequency of the output signal of said variable frequency oscillator in a direction tending to reduce the output signal of said phase detector to zero; first means for producing a first loop acquisition signal at the output thereof when the difference between the frequencies of the output signals of said first loop receiver and said first loop reference oscillator falls below a predetermined threshold level; second means for producing a second loop acquisition signal when the difference between the frequencies of the output signals of said second loop receiver and said second loop reference oscillator falls below a predetermined threshold level; comparator means to produce a slaving signal at the output thereof in accordance with the difference between the frequencies of the output signals of said variable frequency oscillators; a tuning control having an output; first and second slaving relays, each of said first and second slaving relays being adapted to operate at least one single-pole, double-throw switch, said switch including a movable pole, a normally closed contact, and a normally open contact, said tuning control output being connected to each slaving relay normally closed contact, said comparator means output being connected to each slaving relay normally open contact; and first and second override relays each having a pair of normally closed contacts connected in series between said first and second slaving relay poles, respectively, to said first and second loop drive means, respectively, said first means being adapted to energize said first override relay and said second slaving relay when said first loop acquisition signal is produced, said second means being adapted to energize said second override relay and said first slaving relay when said second loop acquisition signal is produced.

Claim 8

The invention as defined in claim 4, wherein each said control means includes a frequency multiplier.

Claim 9

The invention as defined in claim 4, wherein said comparator means includes a phase detector.

Claim 10

The invention as defined in claim 4, including gain control means responsive to the output of said comparator means for reducing the gain of said drive means when the difference between the frequencies of the output signals of said variable frequency oscillators falls below a predetermined threshold level.

Claim 11

The invention as defined in claim 7, wherein said gain control means includes resistors connected to said drive means, a control relay having normally closed contacts to shunt said resistors, and a low-pass filter and rectifier connected from said comparator means to energize said control relay.

Claim 12

The invention as defined in claim 1, wherein said third means includes comparator means to produce an output signal proportional to the difference between the frequencies of the output signals of said variable frequency oscillators, and means for impressing an input signal on said second loop drive means proportional to said comparator means output signal.

Claim 13

The invention as defined in claim 9, wherein said comparator means includes a phase detector.

Claim 14

The invention as defined in claim 1, wherein each said first means includes a frequency multiplier.