Gain control circuit for noise reduction system

Claim 2

In apparatus for recording an information signal on a recording medium by a recording device, gain control means comprising: means defining a first transmission path for compressing said information signal, and including variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which compresses said information signal in a logarithmically linear manner as a function of said information signal, and control means responsive to the compressed information signal from said variable gain amplifier means for producing said control signal; means defining a second transmission path for transmitting said information signal with substantially unity gain; and means for effectively supplying the information signal to said recording device by way of said first path when the level of said information signal is below a predetermined value and for effectively supplying said information signal to said recording device by way of said second path with substantially unity gain when the level of said information signal is above said predetermined value.

Claim 3

In apparatus for recording an information signal on a recording medium by a recording device, gain control means comprising: means defining a first transmission path for compressing said information signal and including variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which compresses said information signal as a function of said information signal, and control means responsive to the compressed information signal from said variable gain amplifier means for producing said control signal, said control means including level detecting means for detecting the level of said compressed information signal from said variable gain amplifier means and for producing a detected output signal in response thereto, and non-linear means for producing said control signal in response to said detected output signal, and in which said level detecting means includes means for logarithmically converting said compressed information signal from said variable gain amplifier means, and amplifier means for producing said detected output signal in response to the logarithmically converted signal; means defining a second transmission path for transmitting said information signal with substantially unity gain; and means for effectively supplying the information signal to said recording device by way of said first path when the level of said information signal is below a predetermined value and for effectively supplying said information signal to said recording device by way of said second path with substantially unity gain when the level of said information signal is above said predetermined value.

Claim 4

In apparatus for recording an information signal on a recording medium by a recording device, gain control means comprising: means defining a first transmission path for compressing said information signal and including variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which compresses said information signal as a function of said information signal, and control means responsive to the compressed information signal from said variable gain amplifier means for producing said control signal, said control means including level detecting means for detecting the level of said compressed information signal from said variable gain amplifier means and for producing a detected output signal in response thereto, and non-linear means for producing said control signal in response to said detected output signal, and in which said level detecting means includes means for logarithmically converting said compressed information signal from said variable gain amplifier means, and amplifier means for producing said detected output signal in response to the logarithmically converted signal; means defining a second transmission path for transmitting said information signal with substantially unity gain; and means for effectively supplying the information signal to said recording device by way of said first path when the level of said information signal is below a predetermined value and for effectively supplying said information signal to said recording device by way of said second path with substantially unity gain when the level of said information signal is above said predetermined value.

Claim 5

In apparatus for recording an information signal on a recording medium by a recording device, gain control means comprising: means defining a first transmission path for compressing said information signal and including variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which compresses said information signal as a function of said information signal, and control means responsive to the compressed information signal from said variable gain amplifier means for producing said control signal, in which said control means includes level detecting means for detecting the amplitude of said compressed information signal from said variable gain amplifier means and for producing a detected output signal in response thereto, and non-linear means for producing said control signal in response to said detected output signal, said non-linear means having an input-output amplitude characteristic with a first linear gradient when the amplitude of said detected output signal is less than a first predetermined value, and a second linear gradient greater than said first gradient when the amplitude of said detected output signal is greater than said first predetermined value; means defining a second transmission path for transmitting said information signal with substantially unity gain; and means for effectively supplying the information signal to said recording device by way of said first path when the amplitude of said information signal is below a second predetermined value corresponding to the first predetermined value and for effectively supplying said information signal to said recording device by way of said second path with substantially unity gain when the amplitude of said information signal is above said second predetermined value.

Claim 6

In apparatus for recording an information signal on a recording medium by a recording device, gain control means comprising: means defining a first transmission path for compressing said information signal and including variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which compresses said information signal as a function of said information signal, and control means responsive to the compressed information signal from said variable gain amplifier means for producing said control signal, in which said control means includes level detecting means for detecting the amplitude of said compressed information signal from said variable gain amplifier means and for producing a detected output signal in response thereto, and non-linear means for producing said control signal in response to said detected output signal, said non-linear means having an input-output amplitude characteristic with a first linear gradient when the amplitude of said detected output signal is less than a first predetermined value, and a second linear gradient greater than said first gradient when the amplitude of said detected output signal is greater than said first predetermined value; means defining a second transmission path for transmitting said information signal with substantially unity gain; and means for effectively supplying the information signal to said recording device by way of said first path when the amplitude of said information signal is below a second predetermined value corresponding to the first predetermined value and for effectively supplying said information signal to said recording device by way of said second path with substantially unity gain when the amplitude of said information signal is above said second predetermined value.

Claim 7

In apparatus for reproducing an information signal from an encoded information signal which has been recorded on a recording medium with the information signal effectively compressed for levels thereof below a predetermined value and with the information signal effectively transmitted with substantially unity gain for levels thereof above said predetermined value; gain control means for reproducing said information signal from said encoded information signal comprising: means defining a first transmission path for expanding said encoded information signal into an expanded signal and including variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which produces said expanded signal as a function of said encoded information signal in a logarithmically linear manner, and control means responsive to said encoded information signal for producing said control signal; and means defining a second transmission path for negatively feeding back said expanded signal to said first transmission path with substantially unity gain.

Claim 8

In apparatus for reproducing an information signal from an encoded information signal which has been recorded on a recording medium with the information signal effectively compressed for levels thereof below a predetermined value and with the information signal effectively transmitted with substantially unity gain for levels thereof above said predetermined value; gain control means for reproducing said information signal from said encoded information signal comprising: means defining a first transmission path for expanding said encoded information signal into an expanded signal and including variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which produces said expanded signal as a function of said encoded information signal in a logarithmically linear manner, and control means responsive to said encoded information signal for producing said control signal; and means defining a second transmission path for negatively feeding back said expanded signal to said first transmission path with substantially unity gain.

Claim 9

In apparatus for reproducing an information signal from an encoded information signal which has been recorded on a recording medium with the information signal effectively compressed for amplitudes thereof below a predetermined value and with the information signal effectively transmitted with substantially unity gain for amplitudes thereof above said predetermined value, gain control means for reproducing said information signal from said encoded information signal comprising: means defining a first transmission path for expanding said encoded information signal into an expanded signal and including variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which produces said expanded signal as a function of said encoded information signal, and control means responsive to said encoded information signal for producing said control signal, in which said control means includes level detecting means for detecting the amplitude of said encoded information signal and for producing a detected output signal in response thereto, non-linear means for producing an output signal in response to said detected output signal, and inverting means for producing said control signal in response to said output signal from said non-linear means, said non-linear means having an input-output amplitude characteristic with a first linear gradient when the amplitude of said detected output signal is less than a second predetermined value corresponding to the first-mentioned predetermined value, and with a second linear gradient when the amplitude of said detected output signal is greater than said second predetermined value; and means defining a second transmission path for negatively feeding back said expanded signal to said first transmission path with substantially unity gain.

Claim 10

In apparatus for reproducing an information signal from an encoded information signal which has been recorded on a recording medium with the information signal effectively compressed for amplitudes thereof below a predetermined value and with the information signal effectively transmitted with substantially unity gain for amplitudes thereof above said predetermined value, gain control means for reproducing said information signal from said encoded information signal comprising: means defining a first transmission path for expanding said encoded information signal into an expanded signal and including variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which produces said expanded signal as a function of said encoded information signal, and control means responsive to said encoded information signal for producing said control signal, in which said control means includes level detecting means for detecting the amplitude of said encoded information signal and for producing a detected output signal in response thereto, non-linear means for producing an output signal in response to said detected output signal, and inverting means for producing said control signal in response to said output signal from said non-linear means, said non-linear means having an input-output amplitude characteristic with a first linear gradient when the amplitude of said detected output signal is less than a second predetermined value corresponding to the first-mentioned predetermined value, and with a second linear gradient when the amplitude of said detected output signal is greater than said second predetermined value; and means defining a second transmission path for negatively feeding back said expanded signal to said first transmission path with substantially unity gain.

Claim 11

In apparatus for recording an information signal on a recording medium by a recording device, gain control means comprising: means defining a first transmission path for compressing said information signal and including variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which compresses said information signal as a function of said information signal, and control means responsive to the compressed information signal from said variable gain amplifier means for producing said control signal, said control means including level detecting means for detecting the level of said compressed information signal from said variable gain amplifier means and for producing a detected output signal in response thereto, and non-linear means for producing said control signal in response to said detected output signal, in which said non-linear means has an input-output level characteristic with a first linear gradient when the level of said detected output signal is less than a first predetermined value, and a second linear gradient greater than said first gradient when the level of said detected output signal is greater than said first predetermined value, and in which said non-linear means includes first and second resistive elements forming a voltage divider for voltage dividing said detected output signal so as to produce said first linear gradient, and means for varying the resistance value of one of said resistive elements for changing the voltage dividing ratio of said voltage divider so as to produce said second linear gradient; means defining a second transmission path for transmitting said information signal with substantially unity gain; and means for effectively supplying the information signal to said recording device by way of said first path when the level of said information signal is below a second predetermined value corresponding to said first predetermined value and for effectively supplying said information signal to said recording device by way of said second path with substantially unity gain when the level of said information signal is above second predetermined value.

Claim 12

In apparatus for recording an information signal on a recording medium by a recording device, gain control means comprising: means defining a first transmission path for compressing said information signal and including variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which compresses said information signal as a function of said information signal, and control means responsive to the compressed information signal from said variable gain amplifier means for producing said control signal, said control means including level detecting means for detecting the level of said compressed information signal from said variable gain amplifier means and for producing a detected output signal in response thereto, and non-linear means for producing said control signal in response to said detected output signal, in which said non-linear means has an input-output level characteristic with a first linear gradient when the level of said detected output signal is less than a first predetermined value, and a second linear gradient greater than said first gradient when the level of said detected output signal is greater than said first predetermined value, and in which said non-linear means includes first and second resistive elements forming a voltage divider for voltage dividing said detected output signal so as to produce said first linear gradient, and means for varying the resistance value of one of said resistive elements for changing the voltage dividing ratio of said voltage divider so as to produce said second linear gradient; means defining a second transmission path for transmitting said information signal with substantially unity gain; and means for effectively supplying the information signal to said recording device by way of said first path when the level of said information signal is below a second predetermined value corresponding to said first predetermined value and for effectively supplying said information signal to said recording device by way of said second path with substantially unity gain when the level of said information signal is above second predetermined value.

Claim 13

Apparatus according to claim 6, in which said means for varying the resistance value includes a series circuit of a diode, means for reverse biasing said diode and a third resistive element, and said series circuit is connected in parallel to said one resistive element.

Claim 14

In apparatus for recording an information signal on a recording medium by a recording device, gain control means comprising: means defining a first transmission path for compressing said information signal and including variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which compresses said information signal as a function of said information signal, control means responsive to the compressed information signal from said variable gain amplifier means for producing said control signal, limiter means for limiting said compressed information signal from said variable gain amplifier means at two independent levels, in which said limiter means includes at least one transistor having a collector-emitter path connected between the output of said variable gain amplifier means and a reference potential; means defining a second transmission path for transmitting said information signal with substantially unity gain; and means for effectively supplying the information signal to said recording device by way of said first path when the level of said information signal is below a predetermined value and for effectively supplying said information signal to said recording device by way of said second path with substantially unity gain when the level of said information signal is above said predetermined value.

Claim 15

In apparatus for recording an information signal on a recording medium by a recording device, gain control means comprising: means defining a first transmission path for compressing said information signal and including variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which compresses said information signal as a function of said information signal, control means responsive to the compressed information signal from said variable gain amplifier means for producing said control signal, limiter means for limiting said compressed information signal from said variable gain amplifier means at two independent levels, in which said limiter means includes at least one transistor having a collector-emitter path connected between the output of said variable gain amplifier means and a reference potential; means defining a second transmission path for transmitting said information signal with substantially unity gain; and means for effectively supplying the information signal to said recording device by way of said first path when the level of said information signal is below a predetermined value and for effectively supplying said information signal to said recording device by way of said second path with substantially unity gain when the level of said information signal is above said predetermined value.

Claim 16

Apparatus according to claim 8, in which said limiter means further includes another transistor connected between the output of said variable gain amplifier means and a reference potential, and a capacitive element connected between the output of said variable gain amplifier means said transistors for imparting a frequency dependency to said limiter means.

Claim 17

In apparatus for recording an information signal on a recording medium by a recording device, gain control means comprising: means defining a first transmission path for compressing said information signal with a first substantially constant compression characteristic when the amplitude of of said information signal is below a predetermined value and with a second substantially constant compression characteristic when the amplitude of said information signal is above said predetermined value; means defining a second transmission path for transmitting said information signal with substantially unity gain and including a resistive element connected in parallel with said first transmission path; and means for effectively supplying the information signal to said recording device by way of said first path when the amplitude of said information signal is below said predetermined value and for effectively supplying said information signal to said recording device by way of said second path with substantially unity gain when the amplitude of said information signal is above said predetermined value.

Claim 18

In apparatus for recording an information signal on a recording medium by a recording device, gain control means comprising: means defining a first transmission path for compressing said information signal with a first substantially constant compression characteristic when the amplitude of of said information signal is below a predetermined value and with a second substantially constant compression characteristic when the amplitude of said information signal is above said predetermined value; means defining a second transmission path for transmitting said information signal with substantially unity gain and including a resistive element connected in parallel with said first transmission path; and means for effectively supplying the information signal to said recording device by way of said first path when the amplitude of said information signal is below said predetermined value and for effectively supplying said information signal to said recording device by way of said second path with substantially unity gain when the amplitude of said information signal is above said predetermined value.

Claim 19

Apparatus according to claim 10; further including amplifier means having an input supplied with the compressed information signal from said first transmission path and with said information signal with substantially unity gain from said second transmission path whereby said compressed information signal and said information signal with substantially unity gain are added at the input of said amplifier means.

Claim 20

In apparatus for reproducing an information signal from an encoded information signal which has been recorded on a recording medium with the information signal effectively compressed for levels thereof below a predetermined value and with the information signal effectively transmitted with substantially unity gain for levels thereof above said predetermined value; gain control means for reproducing said information signal from said encoded information signal comprising: an input terminal; means defining a first transmission path for expanding said encoded information signal into an expanded signal and including variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which produces said expanded signal as a function of said encoded information signal, control means responsive to said encoded information signal for producing said control signal, and limiter means for coring said encoded information signal, in which said limiter means includes first and second diodes connected in parallel and opposing relation between said input terminal and said variable gain amplifier means; and means defining a second transmission path for negatively feeding back said expanded signal to said first transmission path with substantially unity gain.

Claim 21

In apparatus for reproducing an information signal from an encoded information signal which has been recorded on a recording medium with the information signal effectively compressed for levels thereof below a predetermined value and with the information signal effectively transmitted with substantially unity gain for levels thereof above said predetermined value; gain control means for reproducing said information signal from said encoded information signal comprising: an input terminal; means defining a first transmission path for expanding said encoded information signal into an expanded signal and including variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which produces said expanded signal as a function of said encoded information signal, control means responsive to said encoded information signal for producing said control signal, and limiter means for coring said encoded information signal, in which said limiter means includes first and second diodes connected in parallel and opposing relation between said input terminal and said variable gain amplifier means; and means defining a second transmission path for negatively feeding back said expanded signal to said first transmission path with substantially unity gain.

Claim 22

Apparatus according to claim 12; in which said limiter means includes additional amplifier means having input and output terminals, said first and second diodes are connected in parallel between said input and output terminals of said amplifier means, a capacitive element connects said input terminal of the additional amplifier means to a reference potential, and a series circuit of a resistive element and another capacitive element is connected in parallel with another resistive element between the output terminal of said additional amplifier means and said first and second diodes for imparting a frequency characteristic to said limiter means.

Claim 23

In apparatus for reproducing an information signal from an encoded information signal which has been recorded on a recording medium with the information signal effectively compressed for levels thereof below a predetermined value and with the information signal effectively transmitted with substantially unity gain for levels thereof above said predetermined value; gain control means for reproducing said information signal from said encoded information signal comprising: means defining a first transmission path for expanding said encoded information signal into an expanded signal; means defining a second transmission path for negatively feeding back said expanded signal to said first transmission path with substantially unity gain; and a de-emphasis circuit connected to said first and second transmission paths for de-emphasizing the high frequency components of said encoded information signal.

Claim 24

In apparatus for reproducing an information signal from an encoded information signal which has been recorded on a recording medium with the information signal effectively compressed for levels thereof below a predetermined value and with the information signal effectively transmitted with substantially unity gain for levels thereof above said predetermined value; gain control means for reproducing said information signal from said encoded information signal comprising: means defining a first transmission path for expanding said encoded information signal into an expanded signal; means defining a second transmission path for negatively feeding back said expanded signal to said first transmission path with substantially unity gain; and a de-emphasis circuit connected to said first and second transmission paths for de-emphasizing the high frequency components of said encoded information signal.

Claim 25

Apparatus according to claim 14; further including a third transmission path for positively feeding back the high frequency components of said expanded signal to said first transmission path.

Claim 26

In apparatus for recording an information signal on a recording medium by a recording device, gain control means comprising: means defining a first transmission path for compressing said information signal and including variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which compresses said information signal as a function of said information signal, control means responsive to the compressed information signal from said variable gain amplifier means for producing said control signal, and limiter means for limiting said compressed information signal from said variable gain amplifier means at two independent levels, in which said limiter means includes a diode limiter circuit having first and second diodes, each connected in parallel between the output of said variable gain amplifier means and a reference potential, and each being arranged in opposing relation to the other; means defining a second transmission path for transmitting said information signal with substantially unity gain; and means for effectively supplying the information signal to said recording device by way of said first path when the level of said information signal is below a predetermined value and for effectively supplying said information signal to said recording device by way of said second path with substantially unity gain when the level of said information signal is above said predetermined value.

Claim 27

In apparatus for recording an information signal on a recording medium by a recording device, gain control means comprising: means defining a first transmission path for compressing said information signal and including variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which compresses said information signal as a function of said information signal, control means responsive to the compressed information signal from said variable gain amplifier means for producing said control signal, and limiter means for limiting said compressed information signal from said variable gain amplifier means at two independent levels, in which said limiter means includes a diode limiter circuit having first and second diodes, each connected in parallel between the output of said variable gain amplifier means and a reference potential, and each being arranged in opposing relation to the other; means defining a second transmission path for transmitting said information signal with substantially unity gain; and means for effectively supplying the information signal to said recording device by way of said first path when the level of said information signal is below a predetermined value and for effectively supplying said information signal to said recording device by way of said second path with substantially unity gain when the level of said information signal is above said predetermined value.

Claim 28

Apparatus according to claim 16; in which said limiter means further includes a capacitive element connected between said reference potential and said firt and second diodes for providing a second reference potential higher than said first mentioned reference potential for low frequency components of said information signal.

Claim 29

Apparatus according to claim 17; in which said limiter means further includes a first resistive element connected between the output of said variable gain amplifier means and said first and second diodes and a series circuit of a capacitive element and a resistive element connected in parallel with said first resistive element so as to reduce the effective resistance between the output of said variable gain amplifier and said first and second diodes for high frequency components of said information signal.

Claim 30

In apparatus for recording an information signal on a recording medium by a recording device, gain control means comprising: means defining a first transmission path for compressing said information signal; means defining a second transmission path for transmitting said information signal with substantially unity gain and including a resistive element connected in parallel with said first transmission path; means for effectively supplying the information signal to said recording device by way of said first path when the level of said information signal is below a predetermined value and for effectively supplying said information signal to said recording device by way of said second path with substantially unity gain when the level of said information signal is above said predetermined value, said means for effectively supplying including amplifier means having an input signal supplied with the compressed information signal from said first transmission path and with said information signal with substantially unity gain from said second transmission path whereby said compressed information signal and said information signal with substantially unity gain are added at the input of said amplifier means, and pre-emphasis means connected to said first and second transmission paths for pre-emphasizing the high frequency components of said information signal.

Claim 31

In apparatus for recording an information signal on a recording medium by a recording device, gain control means comprising: means defining a first transmission path for compressing said information signal; means defining a second transmission path for transmitting said information signal with substantially unity gain and including a resistive element connected in parallel with said first transmission path; means for effectively supplying the information signal to said recording device by way of said first path when the level of said information signal is below a predetermined value and for effectively supplying said information signal to said recording device by way of said second path with substantially unity gain when the level of said information signal is above said predetermined value, said means for effectively supplying including amplifier means having an input signal supplied with the compressed information signal from said first transmission path and with said information signal with substantially unity gain from said second transmission path whereby said compressed information signal and said information signal with substantially unity gain are added at the input of said amplifier means, and pre-emphasis means connected to said first and second transmission paths for pre-emphasizing the high frequency components of said information signal.

Claim 32

Apparatus according to claim 19; further including means defining a third transmission path for de-emphasizing high level, high frequency components of the information signal whereby a substantially flat frequency characteristic is imparted by said apparatus to high level components of said information signal.

Claim 33

Apparatus according to claim 20; in which said means defining a third transmission path includes high pass filter means for transmitting only high frequency components of said information signal, and means for subtracting said high frequency components of said information signal from the added signal produced by the addition of said compressed information signal and said information signal with substantially unity gain for high levels of said information signal.

Claim 34

In apparatus for recording an information signal on a recording medium by a recording device, gain control means comprising: means defining a first transmission path for compressing said information signal with a first substantially constant compression characteristic when the amplitude of said information signal is below a predetermined value and with a second substantially constant compression characteristic when the amplitude of said information signal is above said predetermined value; means defining a second transmission path for transmitting said information signal with substantially unity gain; and means for effectively supplying the information signal to said recording device by way of said first path when the amplitude of said information signal is below said predetermined value and for effectively supplying said information signal to said recording device by way of said second path with substantially unity gain when the amplitude of said information signal is above said predetermined value.

Claim 35

In apparatus for recording an information signal on a recording medium by a recording device, gain control means comprising: means defining a first transmission path for compressing said information signal with a first substantially constant compression characteristic when the amplitude of said information signal is below a predetermined value and with a second substantially constant compression characteristic when the amplitude of said information signal is above said predetermined value; means defining a second transmission path for transmitting said information signal with substantially unity gain; and means for effectively supplying the information signal to said recording device by way of said first path when the amplitude of said information signal is below said predetermined value and for effectively supplying said information signal to said recording device by way of said second path with substantially unity gain when the amplitude of said information signal is above said predetermined value.

Claim 36

Apparatus according to claim 22; in which said means defining the first transmission path includes variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which compresses said information signal as a function of said information signal, and control means response to the compressed information signal from said variable gain amplifier means for producing said control signal.

Claim 37

Apparatus according to claim 23; in which said control means includes level detecting means for detecting the amplitude of said compressed information signal from said variable gain amplifier means and for producing a detected output signal in response thereto, and non-linear means for producing said control signal in response to said detected output signal.

Claim 38

Apparatus according to claim 23; in which said means defining the first transmission path further includes limiter means for limiting said compressed information signal from said variable gain amplifier at two independent amplitudes.

Claim 39

In apparatus for reproducing an information signal from an encoded information signal which has been recorded on a recording medium with the information signal effectively compressed for amplitudes thereof below a predetermined value and with the information signal effectively transmitted with substantially unity gain for amplitudes thereof above said predetermined value; gain control means for reproducing said information signal from said encoded information signal comprising: means defining a first transmission path for expanding said encoded information signal into an expanded signal with a first substantially constant expansion charcteristic when the amplitude of said information signal is below said predetermined value and with a second substantially constant expansion characteristic when the amplitude of said information signal is above said predetermined value; and means defining a second transmission path for negatively feeding back said expanded signal to said first transmission path with substantially unity gain.

Claim 40

In apparatus for reproducing an information signal from an encoded information signal which has been recorded on a recording medium with the information signal effectively compressed for amplitudes thereof below a predetermined value and with the information signal effectively transmitted with substantially unity gain for amplitudes thereof above said predetermined value; gain control means for reproducing said information signal from said encoded information signal comprising: means defining a first transmission path for expanding said encoded information signal into an expanded signal with a first substantially constant expansion charcteristic when the amplitude of said information signal is below said predetermined value and with a second substantially constant expansion characteristic when the amplitude of said information signal is above said predetermined value; and means defining a second transmission path for negatively feeding back said expanded signal to said first transmission path with substantially unity gain.

Claim 41

Apparatus according to claim 26; in which said means defining the second transmission path includes a feedback resistor for negatively feeding back said expanded signal to said first transmission path.

Claim 42

Apparatus according to claim 26; in which said means defining a first transmission path includes variable gain amplifier means having a gain which varies in response to a control signal supplied thereto and which produces said expanded signal as a function of said encoded information signal, and control means responsive to said encoded information signal for producing said control signal.

Claim 43

Apparatus according to claim 28; in which said control means includes level detecting means for detecting the amplitude of said encoded information signal and for producing a detected output signal in response thereto, non-linear means for producing an output signal in response to said detected output signal, and inverting means for producing said control signal in response to said output signal from said non-linear means.

Claim 44

Apparatus according to claim 28; in which said means defining a first transmission path further includes limiter means for coring said encoded information signal.