Abstract: A phase-based TOF system preferably generates an optical waveform with fast rise and fall times, to enhance modulation contrast, notwithstanding there will be many high order harmonics. The system is preferably operated with an odd number of phases, to reduce system bias error due to the higher order harmonics, while maintaining good modulation contrast, without unduly increasing system memory requirements. Preferably the system can dynamically calibrate (and compensate for) higher order harmonics in the TOF generated optical energy waveform, over time and temperature. Within the optical energy transmission channel, or within the optical energy detection channel, detection amplifier gain may be modified, and/or detector signal integration time may be varied, and/or digital values may be employed to implement calibration and error reduction The resultant TOF system can operate with improved phase-vs-distance characteristics, with reduced calibration requirements.

Abstract: A chord playing attachment and related method is disclosed. The chord playing attachment may be attached to a guitar or similar stringed instrument, and the user may use the chord playing attachment to learn to play the instrument. Unlike other chord playing attachments, the present invention discloses a design that does not function as a capo, which allows the user play chords in standard keys. The present invention also discloses tabs that may be removed or swapped by the user to allow the user to play some chords by pressing the strings directly and some by pressing a finger pad. The present invention encourages novices to learn to play the instrument in stages and eventually remove the invention entirely. A companion teaching manual is also disclosed.

Abstract: A phase-based TOF system preferably generates an optical waveform with fast rise and fall times, to enhance modulation contrast, notwithstanding there will be many high order harmonics. The system is preferably operated with an odd number of phases, to reduce system bias error due to the higher order harmonics, while maintaining good modulation contrast, without unduly increasing system memory requirements. Preferably the system can dynamically calibrate (and compensate for) higher order harmonics in the TOF generated optical energy waveform, over time and temperature. Within the optical energy transmission channel, or within the optical energy detection channel, detection amplifier gain may be modified, and/or detector signal integration time may be varied, and/or digital values may be employed to implement calibration and error reduction The resultant TOF system can operate with improved phase-vs-distance characteristics, with reduced calibration requirements.

Abstract: Phase-based TOF systems operate with reduced depth error due to motion blur, and/or spatial blur, and/or pixel offset by intelligently determining how best to combine pixel values, and how best to compensate for individual pixel offsets. Such determination(s) may be carried out on a per pixel basis, dynamically, in real-time during TOF operation, or on archived TOF data. Offsets for individual pixels may be dynamically calculated and subtracted from the values acquired by those pixels Individual pixel offsets may be calculated for example by combining data acquired by the same pixel at two acquisitions, 180° out of phase with respect to each other. Calculated offsets may be averaged, or on a per pixel basis, and if target object motion is detected, one or more offset calculations can be discarded rather than averaged to reduce motion blur. Offsets acquired a priori during a TOF system calibration procedure may be used.