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Claims  |
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What is claimed is:
1. An auxiliary pick-up for use in a stringed musical instrument having an
electromagnetic pick-up mounted thereon in addition to said
electromagnetic pick-up, which electromagnetic pick-up includes a pole
piece and at least one winding dedicated to each string of said instrument
and mounted in spaced relationship therefrom, the auxiliary pick-up
comprising:
a substantially planar substrate of non-conductive material adapted to be
mounted intermediate said strings and said electromagnetic pick-up in
spaced relationship from said strings;
a plurality of conductive, electrically isolated coils on said substrate,
each coil positioned to be in alignment with a different pole piece when
said substrate is in its mounted position, said coils sensing vibrations
of said strings independently of said windings when said substrate is in
its mounted position.
2. An auxiliary pick-up for use in a stringed musical instrument having an
electromagnetic pick-up mounted thereon, which electromagnetic pick-up
includes a pole piece dedicated to each string of said instrument and
mounted in spaced relationship therefrom, the auxiliary pick-up
comprising:
a substantially planar substrate of non-conductive material adapted to be
mounted intermediate said strings and said electromagnetic pick-up in
spaced relationship from said strings;
a plurality of conductive coils on said substrate, each coil positioned to
be in alignment with a different pole piece when said substrate is in its
mounted position, each coil being formed from a conductive coating on said
substrate and comprising an elongated conductor in the shape of a helix,
said substrate further including means for making an electrical connection
to each coil.
3. An auxiliary pick-up for use in a stringed musical instrument having an
electromagnetic pick-up mounted thereon, which electromagnetic pick-up
includes a pole piece dedicated to each string of said instrument and
mounted in spaced relationship therefrom, the auxiliary pick-up
comprising:
a substantially planar substrate of non-conductive material adapted to be
mounted intermediate said strings and said electromagnetic pick-up in
spaced relationship from said strings;
a plurality of conductive coils on said substrate, each coil positioned to
be in alignment with a different pole piece when said substrate is in its
mounted position, each coil including component conductors on opposite
faces of said substrate, said component conductors being joined by a
conductive connection so as to form one continuous coil.
4. An auxiliary pick-up in accordance with claim 3 wherein each coil is
formed from a conductive coating on said substrate and comprises an
elongated conductor in the shape of a helix, said substrate further
including means for making an electrical connection to each coil.
5. An auxiliary pick-up in accordance with any preceding claim wherein said
substrate includes a hole therethrough corresponding to each coil, each
hole being substantially circumscribed by the corresponding coil and being
dimensioned to receive the corresponding pole piece therein.
6. A separator for use with a plurality of sensors, each providing an
electrical signal with a time-variable envelope representing a respective
received musical sound, each sensor being dedicated to a different sound
source, but also being capable of excitation by other sound sources, said
separator comprising:
a plurality of input terminals each dedicated to receive the signal from a
different sensor;
an output terminal;
a conductive path from each input terminal to said output terminal; and
means responsive to the envelope of the signal applied to each input
terminal for opening the conductive paths from input terminals other than
the one having the fastest build up in the envelope of its received
signal.
7. A separator in accordance with claim 6 wherein said opening means
includes first component for opening the conductive path from each input
terminal as long as the envelope of its received signal fails to build up
faster than at a predetermined threshold rate and a second component
controlled by groups of at least two input terminals for opening the
conductive path from the input terminals in each group other than the one
with the fastest build up in the envelope of its received signal.
8. In combination with a separator in accordance with claims 6 or 7, an
auxiliary pick-up for use in a stringed musical instrument having an
electromagnetic pick-up mounted thereon, which electromagnetic pick-up
includes a pole piece dedicated to each string of said instrument and
mounted in spaced relationship therefrom, the auxiliary pick-up
comprising:
a substantially planar substrate of non-conductive material adapted to be
mounted intermediate said strings and said electromagnetic pick-up in
spaced relationship from said strings;
a plurality of conductive coils on said substrate, each coil positioned to
be in alignment with a different pole piece when said substrate is in its
mounted position; and
means for connecting each of said coils to a respective input terminal to
act as the sensor therefor.
9. In combination with a separator according to claims 6 or 7, a transition
detector responsive to the one signal at said output terminal for
generating a binary signal in which each cycle has a period that is
substantially equal to the corresponding cycle in said one signal, said
transition detector comprising:
a source of an adaptive threshold voltage proportional to the envelope of
said input signal; and
means for generating a binary signal having a triggering edge coincident
with each crossing of said input signal through said threshold level in a
predefined direction.
10. The combination of claim 8 further comprising a transition detector
responsive to the one signal at said output terminal for generating a
binary signal in which each cycle has a period that is substantially equal
to the corresponding cycle in said one signal, said transition detector
comprising:
a source of an adaptive threshold voltage proportional to the envelope of
said input signal; and
means for generating a binary signal having a triggering edge coincident
with each crossing of said input signal through said threshold level in a
predefined direction.
11. The combination of claim 9 further including apparatus for estimating
the period of said one signal, comprising:
means for storing a period estimate;
means for measuring the duration between predefined triggering points in
each cycle of said input signal;
means for generating first and second threshold signals each having a value
which is a different predetermined proportion of said stored period
estimate, said threshold signals defining a variable normal window
therebetween; and
means actuated when said triggering point occurs in a newly received cycle
of said input signal for entering into said storage means a signal
representing the time interval between the triggering points in the two
most recently received cycles, said entering means including means
disabling entry of said interval representing signal when said interval of
time does not fall within said normal window.
12. The combination of claim 10 further including apparatus for estimating
the period of said one signal, comprising:
means for storing a period estimate;
means for measuring the duration between predefined triggering points in
each cycle of said input signal;
means for generating first and second threshold signals each having a value
which is a different predetermined proportion of said stored period
estimate, said threshold signals defining a variable normal window
therebetween; and
means actuated when said triggering point occurs in a newly received cycle
of said input signal for entering into said storage means a signal
representing the time interval between the triggering points in the two
most recently received cycles, said entering means including means
disabling entry of said interval representing signal when said interval of
time does not fall within said normal window.
13. The combination of claim 11 further including a duration timer for
detecting the initiation and termination of each note, comprising:
a threshold voltage source having an output terminal normally providing a
first threshold voltage, said source being actuable to provide a second
threshold voltage in place of said first threshold voltage which is lower
in amplitude than the first threshold voltage;
means actuated when the envelope of said note exceeds said first threshold
voltage for actuating said threshold voltage source.
14. The combination of claim 12 further including a duration timer for
detecting the initiation and termination of each note, comprising:
a threshold voltage source having an output terminal normally providing a
first threshold voltage, said source being actuable to provide a second
threshold voltage in place of said first threshold voltage which is lower
in amplitude than the first threshold voltage;
means actuated when the envelope of said note exceeds said first threshold
voltage for actuating said threshold voltage source.
15. A transition detector responsive to an input signal having a
time-variable envelope representing a sound produced by a musical
instrument for generating a binary signal in which each cycle has a period
that is substantially equal to that of the corresponding cycle in said
input signal, said transition detector comprising:
a source of an adaptive, time variable threshold voltage proportional to
the envelope of said input signal and substantially lower in magnitude
than the peak thereof; and
means for generating a binary signal having a triggering edge coincident
with each crossing of said input signal through said threshold level in a
predefined direction.
16. A transition detector responsive to an input signal having a
time-variable envelope representing a sound produced by a musical
instrument for generating a binary signal in which each cycle has a period
that is substantially equal to that of the corresponding cycle in said
input signal, said transition detector comprising:
a source of an adaptive, time-variable threshold voltage proportional to
the envelope of said input signal and substantially lower in magnitude
than the peak thereof;
means for generating a binary signal having a triggering edge coincident
with each crossing of said input signal through said threshold level in a
predefined direction, wherein said triggering edge is the leading edge of
said binary signal and is produced on the positive crossing of said input
signal;
a source of a second threshold level approximately equal to the average
amplitude of said input signal; and
means in said generating means responsive to the crossing of said input
signal through said second threshold level in a negative direction for
producing a negative transition for said binary signal.
17. In combination with the transition detector of claim 15 or 16,
apparatus for estimating the period of said input signal, comprising:
means for storing a period estimate;
means for measuring the duration between said triggering edges in
consecutive cycles of said binary signal;
means for generating first and second threshold signals each having a value
which is a different predetermined proportion of said stored period
estimate, said threshold signals defining a variable normal window
therebetween; and
means actuated when a triggering edge occurs in a newly received cycle of
said binary signal for entering into said storage means a signal
representing the time interval between the triggering edges in the two
most recently received cycles, said entering means including means
disabling entry of said interval representing signal when said interval of
time does not fall within said normal window.
18. A transition detector responsive to an input signal having a
time-variable envelope representing a sound produced by a musical
instrument for generating a binary signal in which each cycle has a period
that is substantially equal to that of the corresponding cycle in said
input signal, said transition detector comprising:
a source of an adaptive threshold voltage proportional to the envelope of
said input signal;
means for generating a binary signal having a triggering edge coincident
with each crossing of said input signal through said threshold level in a
predefined direction,
means for storing a period estimate;
means for measuring the duration between said triggering edges in
consecutive cycles of said binary signal;
means for generating first and second threshold signals each having a value
which is a different predetermined proportion of said stored period
estimate, said threshold signals defining a variable normal window
therebetween;
means actuated when a triggering edge occurs in a newly received cycle of
said binary signal for entering into said storage means a signal
representing the time interval between the triggering edges in the two
most recently received cycles, said entering means including means
disabling entry of said interval representing signal when said interval of
time does not fall within said normal window;
a threshold voltage source having an output terminal normally providing a
first threshold voltage, said source being actuable to provide a second
threshold voltage in place of said first threshold voltage which is lower
in amplitude than the first threshold voltage;
means actuated when the envelope of said said input signal exceeds said
first threshold voltage for actuating said threshold voltage source; and
means jointly responsive to said input signal and said threshold voltage
source for indicating the presence of said sound only when said input
signal exceeds in amplitude the signal at the output terminal of said
threshold voltage source.
19. The combination of claim 17 further comprising:
means for detecting the occurrence of a predetermined number of consecutive
cycles wherein said time interval is outside said normal window; and
means responsive to said consecutive cycle detecting means for overriding
said entry disabling means.
20. Apparatus in accordance with claim 19 further comprising an initializer
actuated for a predetermined number of cycles of said input signal
immediately following the initiation of a note for overriding said
disabling means.
21. Apparatus for estimating the period of an analog input signal
representing musical notes each having any of a plurality of distinct
starting time, comprising:
means for storing a period estimate;
means for measuring the duration between predefined triggering points in
each cycle of said input signal;
means for generting first and second threshold signals each having a value
which is a different predetermined proportion of said stored period
estimate, said threshold signals defining a variable normal window
therebetween; and
means actuated when said triggering point occurs in a newly received cycle
of said input signal for entering into said storage means a signal
representing the time interval between the triggering points in the two
most recently received cycles, said entering means including means
disabling entry of said interval representing signal when said interval of
time does not fall within said normal window.
22. Apparatus in accordance with claim 21 further comprising:
means for detecting the occurrence of a predetermined number of consecutive
cycles wherein said time interval is outside said normal window; and
means responsive to said consecutive cycle detecting means for overriding
said entry disabling means.
23. Apparatus in accordance with any of claims 21 or 22 further comprising
an initializer actuated for a predetermined number of cycles of said input
signal immediately following the initiation of a note for overriding said
disabling means.
24. Apparatus for estimating the period of an analog input signal
representing musical notes each having a distinct starting time,
comprising:
means for storing a period estimate;
means for measuring the duration between predefined triggering points in
each cycle of said input signal;
means for generating first and second threshold signals each having a value
which is a different predetermined proportion of said stored period
estimate, said threshold signals defining a variable normal window
therebetween;
means actuated when said triggering point occurs in a newly received cycle
of said input signal for entering into said storage means a signal
representing the time interval between the triggering points in the two
most recently received cycles, said entering means including means
disabling entry of said interval representing signal when said interval of
time does not fall within said normal window;
a threshold voltage source having an output terminal normally providing a
first threshold voltage, said source being actuable to provide a second
threshold voltage in place of said first threshold voltage which is lower
an amplitude then the first threshold voltage;
means actuated when the envelope of said note exceeds said first threshold
voltage for actuating said threshold voltage source; and
means jointly responsive to said input signal and said threshold voltage
source for indicating the presence of said sound only when said input
signal exceeds in amplitude the signal at the output terminal of said
threshold voltage source.
25. Apparatus for estimating the period of an analog input signal
representing musical notes each having a distinct starting time and a
time-variable envelope, comprising:
means for storing a period estimate;
means for measuring the duration between predefined triggering points in
each cycle of said input signal;
means for generating first and second threshold signals each having a value
which is a different predetermined proportion of said stored period
estimate, said threshold signals defining a variable normal window
therebetween;
means actuated when said triggering point occurs in a newly received cycle
of said input signal for entering into said storage means a signal
representing the time interval between the triggering points in the two
most recently received cycles, said entering means including means
disabling entry of said interval representing signal when said interval of
time does not fall within said normal window;
an initializer actuated for a predetermined number of cycles of said input
signal immediately following the initiation of a note for overriding said
disabling means;
a threshold voltage source having an output terminal normally providing a
first threshold voltage, said source being actuable to provide a second
threshold voltage in place of said first threshold voltage which is lower
in amplitude than the first threshold voltage;
means actuated when the envelope of said note exceeds said first threshold
voltage for actuating said threshold voltage source; and
means jointly responsive to said input signal and said threshold voltage
source for indicating the presence of said sound only when said input
signal exceeds in amplitude the signal at the output terminal of said
threshold voltage source.
26. In an apparatus including a pitch detector for providing an output
signal estimating the pitch of an analog input signal representing musical
notes each having a time-variable envelope and predefined time of
initialization, a duration timer for detecting the initiation and
termination of each note, comprising:
a threshold voltage source having an output terminal normally providing a
first threshold voltage, said source being actuable to provide a second
threshold voltage in place of said first threshold voltage which is lower
in amplitude than the first threshold voltage and independent thereof in
amplitude;
means actuated when the envelope of said note exceeds said first threshold
voltage for actuating said threshold voltage source;
the initiation of a note being detected when said envelope crosses said
threshold voltage source output signal in a positive going direction and
the termination being detected when it crosses the same in a negative
going direction.
27. In an apparatus including a pitch detector for providing an output
signal estimating the pitch of an analog input signal representing musical
notes each having a time-variable envelope and predefined time of
initialization, a duration timer for detecting the initiation and
termination of each note, comprising:
a threshold voltage source having an output terminal normally providing a
first threshold voltage, said source being actuable to provide a second
threshold voltage in place of said first threshold voltage which is lower
in amplitude than the first threshold voltage and independent thereof in
amplitude, wherein said threshold voltage source comprises:
a plurality of serially connected resistors including a junction between
two of said resistors at which the voltage provided at the output terminal
is present;
normally open switching means connected to shunt at least one of said
resistors, said switching means being actuable to produce a low impedance
across said shunted resistor; and
means for actuating said switching means when said indicating means
indicates the presence of said note;
means actuated when the envelope of said note exceeds said first threshold
voltage for actuating said threshold voltage source;
the initiation of a note being detected when said envelope crosses said
threshold voltage source output signal in a positive going direction and
the termination being detected when it crosses the same in a negative
going direction.
28. Apparatus for simultaneously estimating the period of a plurality of
analog input signals each representing musical notes, comprising:
means defining a plurality of time slots during each of which the apparatus
is dedicated to estimating the period of a respective input signal;
means for storing a period estimate for each input signal in a respective
storage location;
means for measuring the duration between predefined triggering points in
each cycle of each input signal during the respective time slot;
means for generating, during each time slot, first and second threshold
signals each having a value which is a different predetermined proportion
of said period estimate stored for the respective input signal, said
threshold signals defining a respective variable normal window
therebetween; and
means, actuated during the respective time slot when said triggering point
occurs in a newly received cycle of an input signal, for entering into the
respective storage location a signal representing the time interval
between the triggering points in the two most recently received cycles of
said input signal, said entering means including means disabling entry of
said interval representing signal when said interval of time does not fall
within said normal window.
29. A method for eliminating interference between a plurality of sensors,
each providing an electrical signal representing a respective received
musical sound with a time-variable envelope, each sensor being dedicated
to a different sound source, but also being capable of actuation by other
sound sources, said method comprising the steps of:
detecting the envelope representing the build-up of sound from each source;
and
accepting as an output signal the electrical signal of only that sensor
dedicated to the source having the fastest build in its envelope.
30. The method of claim 29 wherein said accepting step includes the steps
of:
sensing the rate of build-up of an envelope only after the rate exceeds a
threshold value; and
comparing the rate of envelope build-up for groups of signals including at
least two of said electrical signals and eliminating from acceptance all
signals which do not have the fastest envelope build in each group.
31. A method for obtaining reference points, each in a substantially fixed
relationship to a cycle of an electrical signal with a time-variable
envelope representing a musical sound, said points being useful for
determining the pitch of said sound by estimating the time interval
between successive reference points, said method comprising the steps of:
generating a threshold signal which is proportional to the envelope of said
electrical signal but substantially lower in magnitude than the peak
thereof; and
detecting a primary reference point whenever said electrical signal crosses
said threshold signal in a predetermined direction.
32. A method for obtaining reference points, each in a substantially fixed
relationship to a cycle of an electrical signal with a time-variable
envelope representing a musical sound, said points being useful for
determining the pitch of said sound by estimating the time interval
between successive reference points, said method comprising the steps of:
generating an adaptive, time-variable threshold signal which is
proportional to the envelope of said electrical signal but substantially
lower in magnitude than the peak thereof;
detecting a primary reference point whenever said electrical signal crosses
said threshold signal in a predetermined direction; and
detecting a secondary reference point whenever said electrical signal
crosses a predefined voltage amplitude, different from said threshold
signal and approximately equal to the average amplitude of said input
signal, in the direction opposite said predetermined direction;
producing a binary signal having opposite transitions coincident with
primary and secondary reference points; and
selecting transitions of the same sense in said binary signal as the points
between which the interval is to be measured.
33. A method for estimating the period of an analog input signal
representing musical notes each having a distinct starting time, said
estimating being accomplished by operating on a timing signal having
triggering points occuring at a predefined point in each cycle of said
input signal, said method comprising the steps of:
for an initialization period comprising at least one cycle of said input
signal subsequent to the start of a note, setting the period estimate
equal to the time interval between the two most recent triggering points;
after said initialization period, generating first and second threshold
levels each being a predetermined proportion of said period estimate, said
threshold levels defining a variable normal window therebetween;
updating the period estimate to be equal to the interval between the two
most recent trigger points only when that interval lies within said normal
window.
34. The method of claim 33 further comprising the steps of:
counting the number of consecutive cycles of said input in which the
interval between consecutive triggering points lies outside said normal
window; and
updating the period estimate to be equal to the most recent interval when
it is the last of a predetermined number of intervals lying outside said
normal window.
35. The method of claim 33 or 34 wherein said triggering points are
obtained by:
generating a threshold signal which is proportional to the envelope of said
input signal; and
producing a triggering point whenever said electrical signal crosses said
threshold signal in a predetermined direction.
36. The method of claim 35 further comprising the steps of:
detecting a secondary triggering point whenever said electrical signal
crosses a predefined voltage amplitude different from said threshold
signal in the direction opposite said predetermined direction;
producing a binary signal having oppositely directed transitions coincident
with triggering points and secondary triggering points; and
selecting consecutive transitions of the same direction in said binary
signal as the triggering points between which the interval is to be
measured.
37. In an apparatus including a pitch detector for providing an output
signal estimating the pitch of an analog input signal representing musical
notes each having a predefined time of initialization, a method for
detecting the initiation and termination of each note, comprising the
steps of:
generating a threshold signal normally having a first value;
detecting the envelope of the input signal;
comparing the input signal envelope to the threshold signal;
detecting the initiation of a note when the input signal envelope first
exceeds the threshold signal and setting the threshold signal to a second
value lower than the first value and independent thereof;
detecting the termination of a note when the envelope first falls below the
threshold signal and setting the threshold equal to the first valve.
38. A method for simultaneously estimating the period of a plurality of
analog signals each representing musical notes having distinct times, said
estimating being accomplished by operating on a timing signal for each
analog signal having triggering points occuring at a predefined point in
each cycle of said analog signal, said method comprising the steps of:
sequentially and repetitively sampling said analog signals, the time of
sampling each signal defining a respective time slot dedicated thereto;
for an initialization period comprising at least one cycle of an analog
signal subsequently to the start of the respective note, during the
respective time slot, setting the period estimate for the time slot equal
to the time interval between the two most | | |
