Transmitter-receiver system

Claim 2

A modulated carrier system, comprising in combination, a transmitter and a receiver, said transmitter comprising output circuit means, means to develop a first frequency carrier in said output circuit means, means to develop a modulation frequency, and means connecting said modulation frequency developing means to said output circuit means to establish a carrier wave output from the transmitter influenced at said modulation frequency rate for a first time period and to terminate said modulation frequency thereafter; said receiver comprising a main load, first means responsive to said first frequency to pass a signal toward said main load, disabling means having an output connected to said main load, means responsive to said modulation frequency, a conductor common to said disabling means and to said modulation frequency responsive means, means establishing said modulation frequency on said conductor, means establishing a disabling voltage from said disabling means on said conductor and operative in the absence of a received signal containing said modulation frequency to disable the signal from actuating said main load, and said means responsive to said modulation frequency having an output connected to terminate said disabling means output for at least a second time period to enable said receiver.

Claim 3

A modulated carrier system as set forth in claim 1, wherein said modulation frequency responsive means establishes said second time period overlapping said first time period.

Claim 4

A modulated carrier system as set forth in claim 1, wherein said modulation frequency developing means develops second and third frequencies, and said connecting means includes separable connections for said third frequency developing means.

Claim 5

A modulated carrier system as set forth in claim 3, wherein said modulation frequency responsive means is responsive to said second and third frequencies, means permanently connecting said second frequency responsive means into said receiver to supply a signal to said main load in response to the proper first and second frequencies, and means establishing said third frequency responsive means selectively disconnectable and connectable to the said receiver to establish said receiver operative to pass a signal to said main load upon the presence of a received signal containing said first, second and third frequencies and subsequently said first and second frequencies.

Claim 6

A modulated carrier system as set forth in claim 3, wherein said modulation frequency responsive means is responsive to said second and third frequencies.

Claim 7

A modulated carrier system as set forth in claim 1, including means establishing at least part of said modulation frequency developing means selectively connectable with said transmitter.

Claim 8

A modulated carrier system as set forth in claim 1, including means establishing at least part of said modulation frequency responsive means selectively connectable with said receiver.

Claim 9

A modulated carrier system as set forth in claim 1, wherein said modulation frequency developing means develops second and third modulation frequencies, means permanently wiring said second frequency developing means into said transmitter to establish a modulated frequency output from said output circuit means, and means establishing plug-in connection of said third frequency developing means to permit operation of said transmitter with only two frequencies or selectively with three frequencies.

Claim 10

A modulated carrier system, comprising in combination, a transmitter and a receiver; said transmitter comprising output circuit means, means to develop a first frequency carrier in said output circuit means, and modulation frequency developing means selectively connectable to said output circuit means to establish a modulated carrier wave output from the transmitter for a first time period and to terminate said modulation frequency thereafter; said receiver comprising a main load, first means responsive to said first frequency to pass a signal toward said main load, modulation frequency responsive means and disabling means selectively connectable to said main load with said disabling means operative in the absence of a received signal containing said modulation frequency to disable the signal from actuating said main load, a first connector as a part of said selectively connectable means, means establishing said modulation frequency on said first connector, means establishing a disabling voltage from said disabling means on said first connector to disable the signal from actuating said main load, and said modulation frequency responsive means having an output connected to terminate said disabling means output for at least a second time period to enable said receiver to thus pass current to said main load upon the presence of a received signal containing said carrier and modulation frequencies.

Claim 11

A modulated carrier system, comprising in combination, a transmitter and a receiver; said transmitter comprising output circuit means, means to develop a first frequency carrier in said output circuit means, and modulation frequency developing means selectively connectable to said output circuit means to establish a modulated carrier wave output from the transmitter for a first time period and to terminate said modulation frequency thereafter; said receiver comprising a main load, first means responsive to said first frequency to pass a signal toward said main load, modulation frequency responsive means and disabling means selectively connectable to said main load with said disabling means operative in the absence of a received signal containing said modulation frequency to disable the signal from actuating said main load, a first connector as a part of said selectively connectable means, means establishing said modulation frequency on said first connector, means establishing a disabling voltage from said disabling means on said first connector to disable the signal from actuating said main load, and said modulation frequency responsive means having an output connected to terminate said disabling means output for at least a second time period to enable said receiver to thus pass current to said main load upon the presence of a received signal containing said carrier and modulation frequencies.

Claim 12

A modulated carrier system as set forth in claim 9, including means supplying an operating voltage from said receiver to said selectively connectable modulation frequency responsive means and disabling means.

Claim 13

A modulated carrier system as set forth in claim 9, including means supplying operating voltages from said transmitter to said selectively connectable modulation frequency developing means.

Claim 14

A modulated carrier system as set forth in claim 9, wherein said modulation frequency responsive means terminates said disabling voltage on said first connector to enable said receiver during said second time period.

Claim 15

A modulated carrier system, comprising in combination, a transmitter and a receiver; said transmitter comprising output circuit means, means to develop a first frequency carrier in said output circuit means, means to develop in said output circuit means a second frequency modulating said carrier frequency, and third frequency developing means selectively connectable to said output circuit means to establish a second frequency modulated carrier wave output from the transmitter influenced at said third frequency rate for a first time period and to terminate said third frequency thereafter; said receiver comprising a main load, first means responsive to said first frequency to pass a signal toward said main load, second means responsive to said second frequency to pass a signal toward said main load, third frequency responsive means and disabling means having an output and selectively connectable to said main load with said disabling means operative to disable said main load in the absence of a received signal containing said third frequency, and said third frequency responsive means having an output connected to terminate said disabling means output for at least a second time period to enable said receiver to thus pass current to said main load upon the presence of a received signal containing said first, second and third frequencies and subsequently said first and second frequencies.

Claim 16

A modulated carrier system, comprising in combination, a transmitter and a receiver; said transmitter comprising output circuit means, means to develop a first frequency carrier in said output circuit means, means to develop in said output circuit means a second frequency modulating said carrier frequency, and third frequency developing means selectively connectable to said output circuit means to establish a second frequency modulated carrier wave output from the transmitter influenced at said third frequency rate for a first time period and to terminate said third frequency thereafter; said receiver comprising a main load, first means responsive to said first frequency to pass a signal toward said main load, second means responsive to said second frequency to pass a signal toward said main load, third frequency responsive means and disabling means having an output and selectively connectable to said main load with said disabling means operative to disable said main load in the absence of a received signal containing said third frequency, and said third frequency responsive means having an output connected to terminate said disabling means output for at least a second time period to enable said receiver to thus pass current to said main load upon the presence of a received signal containing said first, second and third frequencies and subsequently said first and second frequencies.

Claim 17

A modulated carrier system as set forth in claim 13, wherein said third frequency developing means includes a bridge T filter tuned to said third frequency.

Claim 18

A modulated carrier system as set forth in claim 13, wherein said third frequency developing means includes a mechanically vibratable tuning fork.

Claim 19

A modulated carrier system as set forth in claim 13, wherein said third frequency responsive means includes a parallel resonant circuit resonant to said third frequency.

Claim 20

A modulated carrier system as set forth in claim 13, wherein said third frequency responsive means includes a mechanically vibratable tuning fork.