Marmon Company

Robert J Sehnert

Angelo A Bione

Horace E Taylor

A chord recognition system for an electronic musical instrument, namely an electronic organ. A shift register receives data information from the keying lines of selected playing keys. The pattern of the received data is compared against selected normalized chord patterns in a program logic array to determine if the note input sequence is in a known musical relationship such as major, minor, minor sixth, seventh or others. A chord logic circuit receives the information from the programmed logic circuit and further reduces the information to output signals indicating a major, minor, or seventh chord and a pattern found signal. If no chord pattern is detected in the input data sequence, the register shifts the data on its first input line to its last input line and all other data is transferred downward accordingly. A counter sequences at each shift of the data input information. The shifted data is now compared in the programmed logic array as described above. This operation is repeated until a pattern match is found or an entire shift cycle is complete. The type of chord being played is indicated by the output of the chord logic circuit and the root or alphabetic key of the chord being played is indicated by the output of the counter. Each step of the counter indicates a different root or tonic note. Thus, the system recognizes normalized chord patterns and tracks the alphabetic key for recognizable chord patterns. The output from the chord logic circuit and the counter are used as inputs to other organ circuits such as a visual display circuit to illustrate to the organist the chord being played.

Chord recognition system for an electronic musical instrument

The bass note generation system provides one of several different types or styles of bass-line accompaniment for the organist. A chord pattern detector receives signals on keying lines corresponding to keys depressed by the instrument player and attempts to recognize a normalized chord pattern. A counter tracks the operation of the chord pattern detector and provides an output corresponding to the alphabetic note of any recognized chord. If the chord pattern is recognized, the output of the detector and the output of the counter address a normalized and preprogrammed bassline pattern memory. The digital value of the bass note stored in the memory and the outut of the counter are serially added to transpose the normalized bass note to the appropriate musical key and applied to a decorder-keyer circuit at selected time intervals in a musical measure for providing a precomposed musical bassline output. If the instrument player closes the root/fifth switch on the instrument console and the chord pattern detector recognizes a normalized pattern of depressed keys, a digital bass note value corresponding to the root or the fifth bass note of the recognized chord is applied to the decoder-keyer circuit. If the chord pattern detector fails to recognize the combination of keys depressed by the instrument player as a normalized chord pattern, the system defaults into a scanning mode of operation. In the scanning mode, the preprogrammed bassline pattern memory is disabled and the system provides a fixed bassline routine with the notes selected from among the keys actually depressed by the instrument player. If the instrument player selects the root/fifth mode of operation and the combination of depressed keys is not a recognizable chord pattern, the system provides a low-high select routine with the notes corresponding to the lowest and highest frequency keys actually depressed.

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Palatine, IL, United States of America

Robert J Sehnert