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US 4,227,437 AGranted
Frequency detecting apparatus
OwnerThomas L. Inloes, Darwin E. Georgeinventors
Life of this patent
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Abstract
A detecting apparatus for tuning musical instruments receives an input signal from a sound transducer and removes second harmonic content therefrom by means of a filter responsive to a note and octave selection. A phase lock pulse generator receives the filtered output and generates a signal in step with the input sound signal. The generated signal is counted by a note counter during a gating period derived by counting a predetermined number of output cycles of an oscillator started in step with the input signal. Three outputs indicating "on-frequency", "sharp" or "flat" are supplied in the alternative at the end of the gating period in accordance with the count in the note counter at that time.
Claims18
Frequency detection apparatus for tuning a stringed instrument or the like, comprising:
- a transducer for receiving sound information from a vibrating string on said instrument and for converting the same into an electrical signal of like frequency,
- selection means for selecting a note corresponding to a correct frequency to be detected,
- a filter for receiving said electrical signal and responsive to said selection means for filtering second harmonic information from said electrical signal,
- a first oscillator phase locked to the signal provided by said filter for generating a phase locked signal,
- a second oscillator also responsive to the signal provided by said filter to produce a standard frequency output signal initiated in synchronous time relation with the signal provided by said filter,
- a control counter coupled to the output of said second oscillator for counting the output cycles of said standard frequency output signal, and a gating circuit responsive to a count of said control counter for gating said phase locked signal during a gating period as determined by a predetermined counted number of cycles of said standard frequency output signal,
- note counter means coupled for receiving the phase locked signal as gated by said gating circuit for detecting whether the number of output cycles of the gated phase locked signal received during said gating period reaches a predetermined count corresponding to the note selected by said selection means, and
- display means for producing first, second and third indications for respectively indicating substantial identity in frequency between the electrical signal and the note selected by said selection means, or whether the electrical signal is above or below said note, said display means receiving the output of said note counter means substantially at the end of said gating period produced by said gating circuit to determine whether said note counter means has made a full count corresponding to the selected note substantially at the end of said gating period.
5 more elements
Frequency detection apparatus for tuning a stringed instrument or the like, comprising:
- transducer means for receiving sound information from a vibrating string on said instrument and for generating an electrical signal in response thereto,
- first means for supplying a first output responsive to said electrical signal starting in synchronism with said electrical signal,
- second means substantially independent of said first means for supplying a second output responsive to said electrical signal starting in synchronism with said electrical signal, said second means comprising an oscillator and means responsive to said electrical signal for starting oscillation of said oscillator in synchronism with said electrical signal,
- the first means being responsive to said electrical signal to provide a said first output indicative of the frequency of said electrical signal, and the second means providing a standard second output signal, and
- and comparison means for comparing said first output with a predetermined number of cycles of said second output signal to provide an indication whether the first output signal substantially matches a predetermined standard, and including means for indicating whether the first output is higher in frequency than said standard or is lower in frequency than said standard,
- wherein said comparison means for indicating the first output substantially matches the standard includes a first flip-flop means, wherein said means for indicating a higher frequency includes a second flip-flop means, and wherein said means for indicating a lower frequency includes a third flip-flop means.
3 more elements
Frequency detection apparatus for tuning a stringed instrument or the like, comprising:
- transducer means for receiving sound information from a vibrating string on said instrument and for generating an electrical signal in response thereto,
- first means for supplying a first output responsive to said electrical signal starting in synchronism with said electrical signal, said first means comprising an oscillator,
- second means substantially independent of said first means for supplying a second output responsive to said electrical signal starting in synchronism with said electrical signal, said second means comprising an oscillator and means responsive to said electrical signal for starting oscillation of the last mentioned oscillator in synchronism with said electrical signal,
- the first means being responsive to said electrical signal to provide a first output indicative of the frequency of said electrical signal, and the second means providing a standard second output signal, and
- comparison means for comparing said first output with a predetermined number of cycles of said second output signal to provide an indication whether the first output substantially matches a predetermined standard.
2 more elements
Dependencies are inferred from the claim text.