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US 4,905,291 AGranted
Cyberoptic audio level control system
AssigneeRockford Corporation
InventorJames C. Strickland
Life of this patent
Estimating the term…
Abstract
The specification discloses an audio signal level control system including a center-tapped photocell incorporated into an attenuator bridge. The cell elements are monitored while processing the audio signal, and a control circuit regulates the light-emitting device in the cell in response to the monitored bridge values. Preferably, log compression and filtering are performed within the control means. Also preferably, a tracking subtraction principle is used in both the audio and control paths to expand the control dynamic range.
Claims32
An audio level control system comprising:
- means for receiving an audio signal;
- attenuator means for controllably attenuating said audio signal to produce an attenuated audio signal, said attenuating means including means for receiving a control signal, said attenuating means further including a center-tapped photocell;
- means for producing a detection signal indicative of the level of said attenuated audio signal;
- means for receiving a command level signal;
- and
- means for producing a control signal as a function of the command level signal and the detection signal, the control signal being applied to the control signal receiving means of said attenuator means.
3 more elements
An electrical signal level control system comprising:
- an optically actuated attenuator means for attenuating an electrical signal to produce an attenuated electrical signal, said attenuator means including a center-tapped photocell and an attenuator bridge incorporating said photocell;
- and
- control means for controlling said optically actuated attenuator means as a function of actual attenuation and a command level signal.
An electrical signal level control system comprising:
- controllable attenuator means for attenuating an electrical signal to produce an attenuated electrical signal, said attenuator means including a center-tapped photocell;
- command level means for producing a command level signal indicative of a desired attenuation;
- and
- control means for controlling said controllable attenuator means, said control means being responsive to said attenuator means and the command level signal.
1 more element
An electrical signal level control system comprising:
- an optically actuated attenuator means for attenuating an electrical signal to produce an attenuated electrical signal;
- and
- control means for controlling said optically actuated attenuator means as a function of actual attenuation and a command level signal, said control means including log means for log compressing a control signal within said control means.
An audio level control system comprising:
- an optically actuated, center-tapped cell;
- an attenuator bridge including two halves and incorporating said center-tapped cell and having an input port for receiving an audio signal and an output port for outputting an attentuated audio signal;
- interrogation means for introducing an interrogation current into each said half of said attenuator bridge;
- detector means for producing a detection signal as a function of the voltages at each said half of the attenuator bridge;
- and
- control means for controlling said optically actuated, center-tapped cell as a function of the detection signal and a command level signal.
3 more elements
An audio level control system comprising:
- means for receiving an audio signal;
- attenuator means for controllably attenuating said audio signal to produce an attenuated audio signal, said attenuating means including means for receiving a control signal;
- means for producing a detection signal indicative of the level of said attenuated audio signal;
- means for receiving a command level signal;
- means for producing a control signal as a function of the command level signal and the detection signal, the control signal being applied to the control signal receiving means of said attenuator means;
- and
- means for performing a tracking subtraction on both the attentuated audio signal and the detection signal.
4 more elements
An electrical signal level control system comprising:
- an optically actuated attenuator means for attenuating an electrical signal to produce an attenuated electrical signal;
- control means for controlling said optically actuated attenuator means as a function of actual attenuation and a command level signal;
- and
- subtractor means for subtracting a signal from the attenuated electrical signal and a control signal within said control means to expand the dynamic range of the control means.
1 more element
An electrical signal level control system comprising:
- an optically actuated attenuator means for attenuating an electrical signal to produce an attenuated electrical signal, said attenuator means including a center-tapped photocell;
- and
- control means for controlling said optically actuated attenuator means as a function of actual attenuation and a command level signal, said control means including filter means for time averaging a control signal within said control means to suppress transients.
An electrical signal level control system comprising:
- controllable attenuator means for attenuating an electrical signal to produce an attenuated electrical signal;
- command level means for producing a command level signal indicative of a desired attenuation;
- control means for controlling said controllable attenuator means, said control means being responsive to said attenuator means and the command level signal;
- and
- subtractor means for subtracting a signal from the attentuated electrical signal and a control signal within the control means to expand the dynamic range of the control means.
2 more elements
Dependencies are inferred from the claim text.