US 4,054,844 AGranted

Amplifying system

AssigneeNippon Gakki Seizo Kabushiki Kaisha

InventorKenro Oguri

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Abstract

An amplifying system comprises an amplifier having a certain constant gain, a first variable attenuator through which an input signal for this system is inputted to the amplifier, and a second variable attenuator through which the output signal of the amplifier is delivered. The over-all gain of the system is variable from the minimum gain to the maximum gain by gang-operating the two variable attenuators. The two variable attenuators are of such a construction that the attenuation factor of the first attenuator is substantially variable in the operation range near the middle of the variable gain whereas that of the second attenuator is substantially variable in the operation ranges near the minimum and maximum of the variable gain. When the input signal level is low, the second attenuator functions in the near-maximum range, and when high, the first attenuator functions in the middle range, thus delivering an output signal at the rated level. To decrease the output level further, the second attenuator functions in the near-minimum range. The S/N ratio of the output signal is good for various input signal level.

Claims8

Dependent claims

An amplifying system having an overall gain which is adjustable for a gain-variable range which is set for this amplifying system, comprising:

a first variable attenuating means for receiving an input signal for the amplifying system to thereby deliver out said input signal of the level attenuated by this variable attenuating means,
an amplifier having a certain gain for amplifying the signal derived from said first variable attenuating means,
a second variable attenuating means for receiving the output signal of said amplifier to deliver out, as an output signal of the amplifying system, said received output signal of the level attenuated by this variable attenuating means,
said over-all gain being varied for said gain-variable range depending upon the total of the respective attenuation factors of said first and second variable attenuating means,
said gain-variable range including at least a first sub-range covering from the maximum gain value of said gain-variable range to a first gain value which is less than said maximum gain value and a second sub-range covering from said first gain value to a second gain value which is less than said first gain value, and
movable means ganging said first and second variable attenuating means for mutually substantially exclusively changing the respective attenuation factors of said first and second variable attenuating means so that by one movement of said ganging means said second variable attenuating means changes said over-all gain with respect mainly to said first sub-range of said gain-variable range and by another movement of said ganging means said first variable attenuating means changes said over-all gain with respect mainly to said second sub-range of said gain-variable range.

3 more elements

Dependencies are inferred from the claim text.