Ils receiver for aircraft with distortion warning or elimination

Claim 2

In a radio receiver system of the type separably recovering first and second tonal modulations on a received carrier, said tonal modulations comprising different odd harmonics of a basic tone frequency, said receiver comprising means for converting said received carrier to an intermediate frequency and demodulation means receiving said intermediate frequency and recovering therefrom said tonal modulations; means for detecting the presence of signal amplitude limiting in said receiver, said means for detecting comprising frequency selective means receiving the output from said demodulation means and being responsive to pass a predetermined odd harmonic frequency component of said basic tone frequency, including said basic tone frequency and exclusive of said tonal modulation odd harmonics, and annunciating means receiving the output of said frequency selective means and being responsive thereto.

Claim 3

In a radio receiver system of the type separably recovering first and second tonal modulations on a received carrier, said tonal modulations comprising different odd harmonics of a basic tone frequency, said receiver comprising means for converting said received carrier to an intermediate frequency and demodulation means receiving said intermediate frequency and recovering therefrom said tonal modulations; means for detecting the presence of signal amplitude limiting in said receiver, said means for detecting comprising frequency selective means receiving the output from said demodulation means and being responsive to pass a predetermined odd harmonic frequency component of said basic tone frequency, including said basic tone frequency and exclusive of said tonal modulation odd harmonics, and annunciating means receiving the output of said frequency selective means and being responsive thereto.

Claim 4

In a radio receiver system of the type separably recovering first and second tonal modulations on a received carrier, said tonal modulations comprising different odd harmonics of a basic tone frequency, said receiver comprising means for converting said received carrier to an intermediate frequency and demodulation means receiving said intermediate frequency and recovering therefrom said tonal modulations; means for detecting the presence of signal amplitude limiting in said receiver, said means for detecting comprising frequency selective means receiving the output from said demodulation means and being responsive to pass a predetermined odd harmonic frequency component of said basic tone frequency, including said basic tone frequency and exclusive of said tonal modulation odd harmonics, and annunciating means receiving the output of said frequency selective means and being responsive thereto.

Claim 5

A system as defined in claim 1 wherein said demodulating means comprises an amplitude modulation detector, and said frequency selective means comprises a bandpass filter.

Claim 6

A system as defined in claim 1 wherein said demodulating means comprises a synchronous detector including an oscillator, a loop filter, and a phase detector embodied in a phase-locked loop, whereby said oscillator is locked 90* out of phase with said intermediate frequency signal carrier component, and phase detecting means responsive to the in-phase component of said oscillator signal to recover said first and second tonal modulations, said means for detecting the presence of signal limiting receiving the output from said in-phase detecting means.

Claim 7

A system as defined in claim 3 further comprising means connected to the phase detector in said phase-locked loop to detect the presence of quadrature phase tonal modulation signal components, a further frequency selective means responsive to said quadrature signal components, and said annunciating means connected to and being additionally responsive to the output from said further frequency selective means.

Claim 8

A system as defined in claim 1 wherein said means for converting said received carrier signal to an intermediate frequency comprises a local oscillator, mixing means receiving said received signal and the output from said local oscillator, the output from said mixing means comprising said intermediate frequency signal; said system further comprising means for frequenCy modulating said local oscillator by a frequency omega m, further frequency selective means receiving the output from said demodulator means and being responsive to pass at least one of frequency components present in said demodulator means output corresponding to omega m and 2 omega m, and said annunciating means additionally receiving and being responsive to the output from said further frequency selective means.

Claim 9

In a radio receiver system of the type separably recovering first and second tonal modulations on a received carrier, said tonal modulations comprising different odd harmonics of a basic tone frequency, said receiver comprising means for converting said received carrier to an intermediate frequency and demodulation means receiving said intermediate frequency and recovering therefrom said tonal modulations; means for rendering said receiver immune from output signal distortion stemming from symmetrical limiting occurring in said receiver, comprising signal hard limiting means receiving the output from said demodulator means, said signal hard limiting means developing a first polarity output of predetermined magnitude when the magnitude of the signal applied thereto exceeds the mean thereof, said signal hard limiting means developing an opposite polarity output of said predetermined magnitude when the magnitude of the signal applied thereto is less than the mean thereof, first and second frequency selective means receiving the output of said signal hard limiting means and respectively passing signal components as defined by said first and second tonal modulation signals, signal attenuating means receiving the output of that one of said frequency selective means passing the higher order harmonic one of said tonal modulation signals, whereby the amplitudes of the first one and attenuated second one of said tonal modulation signals are insensitive to symmetrical limiting occurring within said receiver.

Claim 10

In a radio receiver system of the type separably recovering first and second tonal modulations on a received carrier, said tonal modulations comprising different odd harmonics of a basic tone frequency, said receiver comprising means for converting said received carrier to an intermediate frequency and demodulation means receiving said intermediate frequency and recovering therefrom said tonal modulations; means for rendering said receiver immune from output signal distortion stemming from symmetrical limiting occurring in said receiver, comprising signal hard limiting means receiving the output from said demodulator means, said signal hard limiting means developing a first polarity output of predetermined magnitude when the magnitude of the signal applied thereto exceeds the mean thereof, said signal hard limiting means developing an opposite polarity output of said predetermined magnitude when the magnitude of the signal applied thereto is less than the mean thereof, first and second frequency selective means receiving the output of said signal hard limiting means and respectively passing signal components as defined by said first and second tonal modulation signals, signal attenuating means receiving the output of that one of said frequency selective means passing the higher order harmonic one of said tonal modulation signals, whereby the amplitudes of the first one and attenuated second one of said tonal modulation signals are insensitive to symmetrical limiting occurring within said receiver.

Claim 11

A system as defined in claim 6 comprising further frequency selective means receiving the output of said signal hard limiting means and passing a signal component present therein corresponding to a predetermined harmonic of said basic tone frequency including said basic tone frequency and exclusive of said first and second tonal modulation harmonics thereof, and annunciating means receiving the output of said further frequency selected means and being activated thereby.

Claim 12

A system as defined in claim 7 wherein said means for converting said received signal to an intermediate frequency comprises a local oscillator, mixing means receiving said received signal and the output from said local oscillator, the output from said mixing means comprising said intermediate frequency signal; said system further comprising means for frequency modulating said local oscillator by a frequency omega m, further frequency selective means receiving the output from said signal hard limiting means and being responsive to pass at least one of frequency components present in said signal hard limiting means output corresponding to omega m and 2 omega m, respectively, said annunciating means additionally receiving and being responsive to the output from said further frequency selective means.

Claim 13

A system as defined in claim 7 further comprising a synchronous detector receiving said intermediate frequency signal, said synchronous detector including an oscillator, a loop filter and a phase detector embodied in a phase-locked loop whereby said oscillator is locked 90* out of phase with said intermediate frequency signal carrier component, and means connected to the phase detector in said phase-locked loop to detect the presence of quadrature-phase tonal modulation signal components, further frequency selected means responsive to said quadrature signal components, and said annunciating means being connected to and additionally responsive to the output from said further frequency selective means.

Claim 14

A system as defined in claim 6 fuRther comprising a synchronous detector receiving said intermediate frequency signal, said synchronous detector including an oscillator, a loop filter and a phase detector embodied in a phase-locked loop whereby said oscillator is locked 90* out of phase with said intermediate frequency signal carrier component, and means connected to the phase detector in said phase-locked loop to detect the presence of quadrature-phase tonal modulation signal components, further frequency selected means responsive to said quadrature signal components, and said annunciating means being connected to and additionally responsive to the output from said further frequency selective means.

Claim 15

A system as defined in claim 6 wherein said means for converting said received carrier signal to an intermediate frequency comprises a local oscillator, mixing means receiving said received signal and the output from said local oscillator, the output from said mixing means comprising said intermediate frequency signal; said system further comprising means for frequency modulating said local oscillator by a frequency omega m, further frequency selective means receiving the output from said signal hard limiting means and being responsive to pass at least one of frequency components present in said signal hard limiting means output corresponding to omega m and 2 omega m, and annunciating means receiving the output from said further frequency selective means and being responsive thereto.

Claim 16

In a radio receiving system of the type separably recovering first and second tonal modulations on a received carrier, said tonal modulations comprising different odd harmonics of a basic tone frequency, said receiver comprising means for converting said received carrier to an intermediate frequency and amplitude detection means receiving said intermediate frequency and recovering therefrom said tonal modulations; means for rendering said receiver immune from output signal distortions stemming from signal amplitude limiting occurring in said receiver, comprising a bistable trigger circuit receiving the output from said amplitude modulation detector, said trigger circuit developing a first polarity output of predetermined magnitude when the magnitude of the signal applied thereto exceeds the mean thereof, said trigger circuit developing an opposite polarity output of said predetermined magnitude when the magnitude of the signal applied thereto is less than the mean thereof, control means for adjusting the switching level of said trigger circuit to the zero mean of the original undistorted input signal which would have been applied to said trigger circuit in the absence of any distortion, first and second frequency selective means receiving the output of said trigger circuit and passing signal components present therein corresponding respectively to said first and second tonal modulation signals, signal attenuating means receiving the output of that one of said frequency selective means passing the higher order harmonic one of said tonal modulation signals, whereby the amplitude of the first one and attenuated second one of said tonal modulation signals are insensitive to both symmetrical and asymmetrical limiting occurring within said receiver.

Claim 17

In a radio receiving system of the type separably recovering first and second tonal modulations on a received carrier, said tonal modulations comprising different odd harmonics of a basic tone frequency, said receiver comprising means for converting said received carrier to an intermediate frequency and amplitude detection means receiving said intermediate frequency and recovering therefrom said tonal modulations; means for rendering said receiver immune from output signal distortions stemming from signal amplitude limiting occurring in said receiver, comprising a bistable trigger circuit receiving the output from said amplitude modulation detector, said trigger circuit developing a first polarity output of predetermined magnitude when the magnitude of the signal applied thereto exceeds the mean thereof, said trigger circuit developing an opposite polarity output of said predetermined magnitude when the magnitude of the signal applied thereto is less than the mean thereof, control means for adjusting the switching level of said trigger circuit to the zero mean of the original undistorted input signal which would have been applied to said trigger circuit in the absence of any distortion, first and second frequency selective means receiving the output of said trigger circuit and passing signal components present therein corresponding respectively to said first and second tonal modulation signals, signal attenuating means receiving the output of that one of said frequency selective means passing the higher order harmonic one of said tonal modulation signals, whereby the amplitude of the first one and attenuated second one of said tonal modulation signals are insensitive to both symmetrical and asymmetrical limiting occurring within said receiver.

Claim 18

A system as defined in claim 12 wherein said control means for adjusting the switching level of said trigger circuit as the zero mean of the undistorted signal which would be applied thereto in the absence of distortion comprises a voltage controlled reference voltage source, a phase detector, further frequency selective means passing a predetermined even harmonic frequency component of the output of said trigger circuit, a first frequency multiplying means multiplying the output from said even harmonic frequency selective means, a second frequency multiplying means receiving the output from one of said first and second frequency selective means and multiplying the output therefrom, said first and second multiplying means being adapted to multiply the respective input signals thereto by predetermined factors to produce common frequency output signals, the outputs from said frequency multipliers being applied as respective inputs to said phase detector, the output of said phase detector being applied to and controlling the output level of said voltage controlled reference voltage source, and the output from said voltage controlled reference source being applied to and adjusting the trigger level of said trigger circuit.

Claim 19

A system as defined in claim 13 wherein said means for converting said received carrier to an intermediate frequency comprises a local oscillator, mixing means receiving said received signal and the output from said local oscillator, the output from said mixing means comprising said intermediate frequency signal; said system further comprising means for frequency modulating said local oscillator by a frequency omega m, further frequency selective means receiving the output from said trigger circuit band being responsive to pass at least one of frequency components present in said trigger circuit output corresponding to omega m and 2 omega m, and annunciating means receiving the output from said further frequency selective means and being activated thereby.

Claim 20

A system as defined in claim 13 further comprising a synchronous detector receiving said intermediate frequency signal, said synchronous detector including an oscillator, a loop filter and a phase detector embodied in a phase-locked loop whereby said oscillator is locked 90* out of phase with said intermediate frequency signal carrier component, means connected to the phase detector in said phase-locked loop to detect the presence of quadrature-phase tonal modulation signal components, further frequency selective means responsive to said quadrature signal components, and said annunciator means being connected to and responsive to the output from said further frequency selective means.

Claim 21

A system as defined in claim 12 further comprising a synchronous detector receiving said intermediate frequency signal, said synchronous detector including an oscillator, a loop filter and a phase detector embodied in a phase-locked loop whereby said oscillator is locked 90* out of phase with said intermediate frequency signal carrier component, means connected to the phase detector in said phase-locked loop to detect the presence of quadrature-phase tonal modulation signal components, further frequency selective means responsive to said quadrature signal components, and said annunciator means being connected to and responsive to the output from said further frequency selective means.

Claim 22

A system as defined in claim 12 wherein said means for converting said received carrier to an intermediate frequency comprises a local oscillator, mixing means receiving said received signal and the output from said local oscillator, the output from said mixing means comprising said intermediate frequency signal; said system further comprising means for frequency modulating said local oscillator by a frequency omega m, further frequency selective means receiving the output from said trigger circuit and being responsive to pass at least one of frequency components present in said trigger circuit output corresponding to omega m and 2 omega m, and annunciating means receiving the output from said further frequency selective means and being activated thereby.

Claim 23

In a radio receiver system of the type separably recovering first and second tonal modulations on a received carrier, said tonal modulations comprising different ones of odd harmonics of a basic tone frequency, said receiver comprising a local oscillator, signal mixing means, said signal mixing means receiving the output from said local oscillator and said received signal and developing an intermediate frequency, output signal demodulator means receiving said intermediate frequency and recovering therefrom said tonal modulations; means for detecting the pResence of non-linear signal amplification as a function of frequency in said receiver, said means for detecting comprising means for frequency modulating said local oscillator by a frequency omega m, frequency selective means receiving the output from said demodulator means and being responsive to pass at least one of frequency components present in said demodulator means output corresponding to omega m and 2 omega m, and annunciating means connected to the output of said frequency selective means and being activated in response thereto.

Claim 24

In a radio receiver system of the type separably recovering first and second tonal modulations on a received carrier, said tonal modulations comprising different ones of odd harmonics of a basic tone frequency, said receiver comprising a local oscillator, signal mixing means, said signal mixing means receiving the output from said local oscillator and said received signal and developing an intermediate frequency, output signal demodulator means receiving said intermediate frequency and recovering therefrom said tonal modulations; means for detecting the pResence of non-linear signal amplification as a function of frequency in said receiver, said means for detecting comprising means for frequency modulating said local oscillator by a frequency omega m, frequency selective means receiving the output from said demodulator means and being responsive to pass at least one of frequency components present in said demodulator means output corresponding to omega m and 2 omega m, and annunciating means connected to the output of said frequency selective means and being activated in response thereto.