Frequency detector

Claim 2

In combination for detecting at a particular frequency an input signal having a variable frequency, means for providing a control signal at the particular frequency, means responsive to the control signal for converting such signal into a plurality of signals each having a displaced phase relationship to the other signals, a plurality of switching means each responsive to an individual one of the phase-displaced control signals and to the input signal for providing an output signal in accordance with the frequency and phase relationships between the individual one of the phase-displaced control signals and the input signal, and an ''''or'''' network connected to the switching means in the plurality to pass the signals passing through the switching means in the plurality, the ''''or'''' network including a plurality of unidirectional means each associated with an individual one of the switching means and having characteristics of passing signals of only one polarity from the associated switching means and having an output common with the outputs of the other unidirectional means.

Claim 3

The combination set forth in claim 1, including a plurality of means each associated with a different one of the switching means for providing a particular time constant to control the passage of signals through the switching means and each connected to the associated one of the unidirectional means for introducing to the unidirectional means the signals passing through the associated switching means.

Claim 4

In combination for detecting at a particular frequency an input signal having a variable frequency, means for providing a control signal having the particular frequency, means responsive to the input signal for providing a plurality of control signals each having a quadrature phase relationship to the other control signals in the plurality, a plurality of switching means each connected to receive an individual one of the phase-displaced control signals and the input signal to produce a signal having an output in accordance with a particular relationship of frequency and phase between the individual ones of the control signals and the input signal, an ''''or'''' network having a plurality of members each connected to an individual one of the switching means and having a common output with the other members and having characteristics of passing only signals of one polarity to indicate the maximum amplitude of all of the signals passing through the switching means, and means responsive to the signals passing through the common output of the ''''or'''' network to provide an indication, through the amplitude of the signals passing through the ''''or'''' network, that the input signals has the particular frequency.

Claim 5

In combination for detecting at a particular frequency an input signal having a variable frequency, means for providing a control signal having the particular frequency, means responsive to the input signal for providing a plurality of control signals each having a quadrature phase relationship to the other control signals in the plurality, a plurality of switching means each connected to receive an individual one of the phase-displaced control signals and the input signal to produce a signal having an output in accordance with a particular relationship of frequency and phase between the individual ones of the control signals and the input signal, an ''''or'''' network having a plurality of members each connected to an individual one of the switching means and having a common output with the other members and having characteristics of passing only signals of one polarity to indicate the maximum amplitude of all of the signals passing through the switching means, and means responsive to the signals passing through the common output of the ''''or'''' network to provide an indication, through the amplitude of the signals passing through the ''''or'''' network, that the input signals has the particular frequency.

Claim 6

The combination set forth in claim 3, including a plurality of means each connected to an individual one of the switching means to provide a timing constant for the associated switching means to control the passage of signals through the switching means.

Claim 7

The combination set forth in claim 2 wherein each of the switching means includes an FET junction transistor and wherein the means providing a timing constant for each FET junction transistor includes a resistance and a capacitor connected in series with the FET junction transistor.

Claim 8

In combination for detecting at a particular frequency an input signal having a variable frequency, means for providing a control signal having the particular frequency, means responsive to the input signal for providing a plurality of control signals each having a particular displaced relationship in phase to the other signals in the plurality, a plurality of means for individually comparing the frequency and phase of each of the control signals with the frequency and phase of the input signal to produce a signal when the frequency and phase of the individual ones of the control signals correspond to the frequency and phase of the input signal, and output means operatively coupled to the comprising means and having a common output for providing an output indication at the common output when the comparing means produces at least one signal with at least a particular amplitude, the output means including a plurality of members each operatively coupled to an individual one of the comparing means and having characteristics for passing the signals from the associated one of the comparing means only when the signals have a particular polarity.

Claim 9

In combination for detecting at a particular frequency an input signal having a variable frequency, means for providing a control signal having the particular frequency, means responsive to the input signal for providing a plurality of control signals each having a particular displaced relationship in phase to the other signals in the plurality, a plurality of means for individually comparing the frequency and phase of each of the control signals with the frequency and phase of the input signal to produce a signal when the frequency and phase of the individual ones of the control signals correspond to the frequency and phase of the input signal, and output means operatively coupled to the comprising means and having a common output for providing an output indication at the common output when the comparing means produces at least one signal with at least a particular amplitude, the output means including a plurality of members each operatively coupled to an individual one of the comparing means and having characteristics for passing the signals from the associated one of the comparing means only when the signals have a particular polarity.

Claim 10

The combination set forth in claim 6 wherein the comprising means constitute switching means each connected to receive an individual one of the control signals and the input signal.

Claim 11

The combination set forth in claim 6 wherein the comparing means individually include a resistance and a capacitance in series and provided with a particular time constant to pass signals only when the frequency and phase of the individual ones of the control signals correspond to the frequency and phase of the input signal.

Claim 12

The combination set forth in claim 8 wherein the comparing means constitute FET junction transistors and wherein a resistance and a capacitance are in series with the FET junction transistor and wherein the FET junction transistor becomes conductive when the phase of the individual one of the control signals corresponds to the phase of the control signal.