Resources Contact Us Home
Pitch detection apparatus

Image Number 5 for United States Patent #4688464.

A pitch detector is disclosed that automatically recognizes the pitch of musical notes quickly and outputs the pitch information in a variety of formats. The detector employs a microprocessor that samples the signal from a musical instrument or voice at regular intervals using an analog-to-digital converter and then utilizes both amplitude and time information from the waveform to determine the fundamental period of the note, while rejecting the harmonic components. The microprocessor analyzes the waveform looking for peaks that are approximately equal in amplitude separated by opposite polarity peaks. The time intervals between the peaks must be approximately equal too. Timing information is measured using more than one point on the waveform to avoid inaccuracies caused by temporary distortions of the waveform. The timing points are chosen at points where the slope of the waveform is high for substantially optimal accuracy. To filter out erroneous readings caused by pitch detection during note transition or noise, additional processing of the data is performed to cause a second corroborating reading to be taken when a note transition that is uncommon musically is detected.

  Recently Added Patents
Providing definitions that are sensitive to the context of a text
Methods and systems for facilitating stimulation of one or more stimulation sites
Distributed physics based training system and methods
Spliced optical cable assembly
High power quantum dot optical light source
Adapter for increasing the stroke length of a fastener installation tool
  Randomly Featured Patents
Nanoparticles from slightly oxidised cellulose
Window component extrusion
Manual or self-adjusting reel mower
Apparatus and method for tissue removal
Card for retaining items therein
Parallel processing image encoding device with variable length coding
Method of removing radioactive waste from oil
Systems and methods for allocating bits to macroblocks within a picture depending on the motion activity of macroblocks as calculated by an L1 norm of the residual signals of the macroblocks
Athletic shoe with mesh reinforcement
Locking arrangement for a household refrigerator