Dual-channel logarithmic amplifier

Claim 2

A dual-channel amplifier arrangement comprising first and second amplifier means having respective inputs and outputs and at least one of said first and second amplifier means comprising a logarithmic amplifier; band pass filter means; means connecting the input of said second amplifier means to a source of signals around said band pass filter means; means connecting the input of said first amplifier means to the source of signals through said band pass filter means; and feedback means coupled between the output of said second amplifier means and the input of said first amplifier means to apply the output of said second amplifier means to the input of said first amplifier means for reducing the input gain to said first amplifier means when there are high magnitude components in said wide band but outside of said narrow band at the same time that there are components in said narrow band to thereby prevent said first amplifier means from being saturated by said high magnitude components, whereby said first amplifier means is made readily responsive to the selected frequency components of said input signal despite the simultaneous existence of said high magnitude components.

Claim 3

An amplifier arrangement as defined in claim 1, wherein said first and second amplifier means each comprise a plurality of intermediate-frequency amplification stages connected to a detector means.

Claim 4

An amplifier arrangement defined in claim 2, wherein each said first and second amplifier means further comprise a differential amplification stage connected between said detector means and said respective output.

Claim 5

Apparatus for detecting and amplifying selected components of an input signal comprising a source of a frequency modulated input signal which includes a carrier signal, information containing components in a narrow band width, and components with frequencies adjacent those of the information containing components of the input signal; filter means for receiving and passing the narrow band width portion of said input signal; a first amplifier means comprising a first amplifier section for amplifying the narrow band width portion of said input signal which includes at least one stage capable of logarithmically amplifying said input signal, a section for demodulating said amplified signal to remove the carrier therefrom, and a second amplifier section for amplifying the demodulated signal; means for conducting the amplified, demodulated signal to a user unit; and means for reducing the input gain to the first amplifier section of the first amplifier means when the input signal includes high magnitude components with frequencies adjacent those embraced in said narrow band width to thereby prevent said amplifier section from being saturated or overloaded by said high magnitude components, whereby said amplifier section is made readily responsive to components of the input signal in said narrow band width despite the presence of said high magnitude components in said signal, said last-mentioned means comprising a second amplifier means having an input connected to said input signal source around said filter means, a first amplifier section for amplifying the input signal which includes at least one stage capable of logarithmically amplifying said input signal, a demodulator section for removing the carrier signal from the amplified input signal, a second amplifier section for amplifying the demodulated signal, and means for applying the amplified, demodulated signal produced by the second amplifier section of said amplifier means to the input of said first amplifier section of the first amplifier means.

Claim 6

Apparatus for detecting and amplifying selected components of an input signal comprising a source of a frequency modulated input signal which includes a carrier signal, information containing components in a narrow band width, and components with frequencies adjacent those of the information containing components of the input signal; filter means for receiving and passing the narrow band width portion of said input signal; a first amplifier means comprising a first amplifier section for amplifying the narrow band width portion of said input signal which includes at least one stage capable of logarithmically amplifying said input signal, a section for demodulating said amplified signal to remove the carrier therefrom, and a second amplifier section for amplifying the demodulated signal; means for conducting the amplified, demodulated signal to a user unit; and means for reducing the input gain to the first amplifier section of the first amplifier means when the input signal includes high magnitude components with frequencies adjacent those embraced in said narrow band width to thereby prevent said amplifier section from being saturated or overloaded by said high magnitude components, whereby said amplifier section is made readily responsive to components of the input signal in said narrow band width despite the presence of said high magnitude components in said signal, said last-mentioned means comprising a second amplifier means having an input connected to said input signal source around said filter means, a first amplifier section for amplifying the input signal which includes at least one stage capable of logarithmically amplifying said input signal, a demodulator section for removing the carrier signal from the amplified input signal, a second amplifier section for amplifying the demodulated signal, and means for applying the amplified, demodulated signal produced by the second amplifier section of said amplifier means to the input of said first amplifier section of the first amplifier means.

Claim 7

The apparatus of claim 4, wherein the second amplifier section of each of said amplifying means includes a differential amplifier.

Claim 8

The apparatus of claim 4, together with means for varying the overall level of the amplified, modulated signal from the second amplifying means to thereby alter the extent to which said signal alters the gain to the first amplifier section of saiD first signal amplifying means.

Claim 9

Apparatus for detecting and amplifying selected components of an input signal comprising a source of a frequency modulated input signal which includes a carrier signal, information containing components in a narrow band width, and components with frequencies adjacent those of the information containing components of the input signal; filter means for receiving and passing the narrow band width portion of said input signal; a first amplifier means comprising a first amplifier section for amplifying the narrow band width portion of said input signal, a section for demodulating said amplified signal to remove the carrier therefrom, and a second amplifier section for amplifying the demodulated signal; means for conducting the amplified, demodulated signal to a user unit; means for reducing the input gain to the first amplifier section of the first amplifier means when the input signal includes high magnitude components with frequencies adjacent those embraced in said narrow band width to thereby prevent said amplifier section from being saturated or overloaded by said high magnitude components, whereby said amplifier section is made readily responsive to components of the input signal in said narrow band width despite the presence of said high magnitude components in said signal, said last-mentioned means comprising a second amplifier means having an input connected to said input signal source around said filter means, a first amplifier section for amplifying the input signal, a demodulator section for removing the carrier signal from the amplified input signal, a second amplifier section for amplifying the demodulated signal, and means for applying the amplified, demodulated signal produced by the second amplifier section of said amplifier means to the input of said first amplifier section of the first amplifier means; and circuit means so connected between said first and second amplifying means as to provide positive feedback from said second amplifying means to said first amplifying means and thereby increase the stability of said first amplifier means.

Claim 10

Apparatus for detecting and amplifying selected components of an input signal comprising a source of a frequency modulated input signal which includes a carrier signal, information containing components in a narrow band width, and components with frequencies adjacent those of the information containing components of the input signal; filter means for receiving and passing the narrow band width portion of said input signal; a first amplifier means comprising a first amplifier section for amplifying the narrow band width portion of said input signal, a section for demodulating said amplified signal to remove the carrier therefrom, and a second amplifier section for amplifying the demodulated signal; means for conducting the amplified, demodulated signal to a user unit; means for reducing the input gain to the first amplifier section of the first amplifier means when the input signal includes high magnitude components with frequencies adjacent those embraced in said narrow band width to thereby prevent said amplifier section from being saturated or overloaded by said high magnitude components, whereby said amplifier section is made readily responsive to components of the input signal in said narrow band width despite the presence of said high magnitude components in said signal, said last-mentioned means comprising a second amplifier means having an input connected to said input signal source around said filter means, a first amplifier section for amplifying the input signal, a demodulator section for removing the carrier signal from the amplified input signal, a second amplifier section for amplifying the demodulated signal, and means for applying the amplified, demodulated signal produced by the second amplifier section of said amplifier means to the input of said first amplifier section of the first amplifier means; and circuit means so connected between said first and second amplifying means as to provide positive feedback from said second amplifying means to said first amplifying means and thereby increase the stability of said first amplifier means.

Claim 11

Apparatus for detecting and amplifying selected components of an input signal comprising a source of a frequency modulated input signal which includes a carrier signal, information containing components in a narrow band width, and components with frequencies adjacent those of the information contaIning components of the input signal; filter means for receiving and passing the narrow band width portion of said input signal; a first amplifier means comprising a first amplifier section for amplifying the narrow band width portion of said input signal, a section for demodulating said amplified signal to remove the carrier therefrom, and a second amplifier section for amplifying the demodulated signal; means for conducting the amplified, demodulated signal to a user unit; means for reducing the input gain to the first amplifier section of the first amplifier means when the input signal includes high magnitude components with frequencies adjacent those embraced in said narrow band width to thereby prevent said amplifier section from being saturated or overloaded by said high magnitude components, whereby said amplifier section is made readily responsive to components of the input signal in said narrow band width despite the presence of said high magnitude components in said signal, said last-mentioned means comprising a second amplifier means having an input connected to said input signal source around said filter means, a first amplifier section for amplifying the input signal, a demodulator section for removing the carrier signal from the amplified input signal, a second amplifier section for amplifying the demodulated signal, and means for applying the amplified, demodulated signal produced by the second amplifier section of said amplifier means to the input of said first amplifier section of the first amplifier means; and means for providing negative feedback from the output side of the second amplifier section in said first amplifying means to the input side of the first amplifier section therein.

Claim 12

Apparatus for detecting and amplifying selected components of an input signal comprising a source of a frequency modulated input signal which includes a carrier signal, information containing components in a narrow band width, and components with frequencies adjacent those of the information contaIning components of the input signal; filter means for receiving and passing the narrow band width portion of said input signal; a first amplifier means comprising a first amplifier section for amplifying the narrow band width portion of said input signal, a section for demodulating said amplified signal to remove the carrier therefrom, and a second amplifier section for amplifying the demodulated signal; means for conducting the amplified, demodulated signal to a user unit; means for reducing the input gain to the first amplifier section of the first amplifier means when the input signal includes high magnitude components with frequencies adjacent those embraced in said narrow band width to thereby prevent said amplifier section from being saturated or overloaded by said high magnitude components, whereby said amplifier section is made readily responsive to components of the input signal in said narrow band width despite the presence of said high magnitude components in said signal, said last-mentioned means comprising a second amplifier means having an input connected to said input signal source around said filter means, a first amplifier section for amplifying the input signal, a demodulator section for removing the carrier signal from the amplified input signal, a second amplifier section for amplifying the demodulated signal, and means for applying the amplified, demodulated signal produced by the second amplifier section of said amplifier means to the input of said first amplifier section of the first amplifier means; and means for providing negative feedback from the output side of the second amplifier section in said first amplifying means to the input side of the first amplifier section therein.

Claim 15

The apparatus defined in claim 9, wherein the feedback provided by said feedback providing means is a negative feedback.

Claim 18

An apparatus as defined in claim 11, wherein both said first and second amplifier means include detector means for demodulating signals amplified therein.

Claim 19

The apparatus defined in claim 12, further including selector means for selectively disconnecting said first amplifier means from said second amplifier means, said selector means effecting a negative feedback connection from the output of said first amplifier means to the input thereof.

Claim 20

An apparatus as defined in claim 13, wherein both said feedback providing means from said second amplifier means to said first amplifier means and said negative feedback connectiOn from the output of said first amplifier means to the input thereof are adjustable.

Claim 21

A dual-channel amplifier arrangement for producing amplified components of a signal in a narrow frequency band despite the existence of signal components of greater magnitude in frequency bands adjacent thereto comprising first and second amplifier means having respective inputs and outputs; band pass filter means, means connecting the input of said second amplifier means to a source of signals around said band pass filter means, whereby said second amplifier means will receive signal components having a wide range of frequencies; means connecting the input of said first amplifier means to the source of signals through said band pass filter means whereby said first filter means will receive only those signal components in the narrow frequency band; and means for preventing the first amplifier from being saturated when there are signal components of high magnitude in frequencies adjacent but outside of said narrow frequency band which comprises feed back means coupled between the output of said second amplifier means and the input of said first amplifier means, whereby said first amplifier means is made readily responsive to the selected frequency components of said input signal despite the simultaneous existence of said high magnitude components.

Claim 22

A dual-channel amplifier arrangement for producing amplified components of a signal in a narrow frequency band despite the existence of signal components of greater magnitude in frequency bands adjacent thereto comprising first and second amplifier means having respective inputs and outputs; band pass filter means, means connecting the input of said second amplifier means to a source of signals around said band pass filter means, whereby said second amplifier means will receive signal components having a wide range of frequencies; means connecting the input of said first amplifier means to the source of signals through said band pass filter means whereby said first filter means will receive only those signal components in the narrow frequency band; and means for preventing the first amplifier from being saturated when there are signal components of high magnitude in frequencies adjacent but outside of said narrow frequency band which comprises feed back means coupled between the output of said second amplifier means and the input of said first amplifier means, whereby said first amplifier means is made readily responsive to the selected frequency components of said input signal despite the simultaneous existence of said high magnitude components.

Claim 23

The dual channel amplifier arrangement of claim 15, wherein said first and second amplifier means have substantially the same center frequency.

Claim 24

The dual channel amplifier arrangement of claim 15, wherein said feed back means is constructed to produce a a capacitive feed back between said second and first amplifier means.

Claim 25

The dual channel amplifier arrangement of claim 15, wherein said band pass filter means comprises a plurality of filter means of different band widths and means for connecting the input of said first amplifier means to said source of signals through different ones of said filter means to thereby change the width of the band of frequency components which can be transmitted to said first amplifier means.

Claim 26

The dual channel amplifier arrangement of claim 15, wherein said first and second amplifier means both include circuit components for logarithmically amplifying the input signals transmitted thereto.

Claim 27

The dual channel amplifier arrangement of claim 15, wherein said first amplifier means comprises a first amplifier section for amplifying the narrow band width portion of said input signal, a section for demodulating said amplified signal to remove the carrier therefrom, and a second amplifier section for amplifying the demodulated signals; wherein said second amplifier means comprises a first amplifier section for amplifying the input signal, a demodulator section for removing the carrier signal from the amplified input signal, and a second amplifier section for amplifying the demodulated signal; and wherein said feedback means comprises means for applying the amplified, demodulated signal produced by the second amplifier section of said amplifier means to the input of said first amplifier section of the first amplifier means.