Abstract: A method of operating electro-acoustical transducers such as PMUTs involves applying to the transducer an excitation signal over an excitation interval, acquiring at the transducer a ring-down signal indicative of the ring-down behavior of the transducer after the end of the excitation interval, and calculating, as a function of said ring-down signal, a resonance frequency of the electro-acoustical transducer. A bias voltage of the electro-acoustical transducer can be controlled as a function of the resonance frequency. An acoustical signal received can be transduced into an electrical reception signal and a damping parameter of the electro-acoustical transducer can be calculated as a function of the ring-down signal so that a cross-correlation reference signal can be synthesized as a function of the resonance frequency and the damping ratio of the electro-acoustical transducer.

Abstract: Methods and apparatus for recording and analyzing echolocation calls using zero crossing and/or digital sampling (full spectrum analysis) techniques, and for optimizing trigger thresholds used to activate recording in response to detection of an echolocation call.

Abstract: In order to simplify a manufacturing process and reduce cost and power consumption by providing an ultrasonic diagnostic apparatus including a carrier signal generating circuit excellent in IC implementation, a carrier signal generating circuit for generating an output voltage Vo applied to an ultrasonic probe 41 includes cascaded source follower type NMOSFETs 11 to 14, a variable current source 31, and a constant current source for biasing 32. The probe 41 can be made to generate the output voltage Vo with arbitrary amplitude by controlling a gate voltage V4 by controlling the output current value of the variable current source 31. In addition, a voltage applied to each NMOSFET can be divided by connecting the NMOSFETs 11 to 14 in a multi-stage manner. Accordingly, the withstand voltage of the NMOSFET may be low.

Abstract: An integrated single channel or multi-channel ultrasound transmitter that minimizes the number of input connections to a controller such as an FPGA, field programmable gate array, or a custom integrated circuit in an ultrasound system. The method is accomplished by integrating, in low voltage logic, a means to store and or program the patterns required for the transmitter output. The number of logic input connections can be further reduced by further integrating, in low voltage logic, programmable individual time delays and frequency divider for each transmitter output.

Abstract: A remote power delivery system includes an electrically-conductive plate disposed adjacent to a sensor system of an underwater vehicle's hull. At least one toroidal coil is disposed between the plate and the face of the sensor system exposed to water. An AC voltage is applied to the plate so that a time-harmonic voltage is induced in each toroidal coil.

Abstract: A device for the attenuation of an anti-resonant circuit which has a first capacitor and a secondary inductance. A signal is able to be coupled into the anti-resonant circuit via a primary inductance. An attenuator is connected in parallel to a switching device and to the secondary inductance and/or the primary inductanace.

Abstract: A signal decay time adjusting method is used in an ultrasonic transducer. Firstly, a first driving signal is generated by a pre-processing module. When the first driving signal is received, an ultrasonic transmitting/receiving module generates vibration and transmits a sensing wave according to the first driving signal. Then, the pre-processing module stops generating the first driving signal so that the vibration generated within the ultrasonic transmitting/receiving module is decayed as a decay signal. Then, a second driving signal is generated by the pre-processing module according to the first driving signal, and the second driving signal is transmitted to the ultrasonic transmitting/receiving module. When the second driving signal is received, the decay signal is offset according to the second driving signal, so that a decay time of the decay signal is shortened. When the sensing wave is reflected by an object, a reflective wave is received by the ultrasonic transmitting/receiving module.

Abstract: A measurement system for capturing a transit time, phase, or frequency of energy waves propagating through a propagation medium is disclosed. The measurement system comprises two different closed-loop feedback paths. The first path includes a driver circuit (628), a transducer (604), a propagation medium (602), a transducer (606), and a zero-crossing receiver (640). The zero-crossing receiver (640) detects transition states of propagated energy waves in the propagation medium including the transition of each energy wave through a mid-point of a symmetrical or cyclical waveform. A second path includes the driver circuit (1228), a transducer (1204), a propagation medium (1202), a reflecting surface (1206), and an edge-detect receiver (1240). Energy waves in the propagating medium (1202) are reflected at least once. The edge-detect receiver (1240) detects a wave front of an energy wave. Each positive closed-loop path maintains the emission, propagation, and detection of energy waves in the propagation medium.

Abstract: The transducer circuit includes a transducer component, a drive circuit for the transducer component, a control port for coupling the drive circuit to a control unit and a modulator. The modulator has an input port for receiving a signal or data from another device. The modulator has an output which is coupled to an output stage in the drive circuit. The modulator operates to transmit data, received at the input port, through the drive circuit and the control port to a control unit.

Abstract: A system and method simultaneously transmits sound waves through a plurality of sonar elements without interference, such as for the purpose of tracking objects underwater. The system has a pulse generator with a plurality of transceivers connected to the pulse generator. A plurality of sonar elements is connected to the plurality of transceivers, with at least one sonar element per transceiver. A sonar signal is sent from the pulse generator to each sonar element, passing intermediately through a transceiver.

Abstract: An acoustic method and apparatus for an acoustic system use a transceiver module, which can transmit to a transmit acoustic element of a transmit sonar array and receive from a receive acoustic element of a receive sonar array in accordance with a common transmit/receive control signal.

Abstract: A switch that couples transducer signal to a specific sounder of multiple sounders in response to a sensed signal from the specific sounder. The switch can include a first detection circuit that determines the sounder that is requesting the first transducer signal and a first control circuit that couples the first transducer signal to the requesting sounder. The switch can further include a second detection circuit that determines the sounder that is requesting the second transducer signal and a second control circuit that couples the second transducer signal to the requesting sounder.

Abstract: Swimmers are detected in a given body of water by dispersing sensors throughout the water column. The sensors adhere to the swimmer and reflect acoustic energy. Acoustic energy is broadcast in the water and the swimmer is detected by the characteristic motion of the sensors clinging to the swimmer as detected by acoustic monitors. The sensors may also fluoresce and be detectible by optical monitors when a portion of the swimmer is above the water.

Abstract: A method and apparatus for controlling pulses in a pulse-echo level measurement or time-of-flight ranging system. The apparatus comprises a controller, a transducer, and an energy storage device. The energy storage device is operatively coupled to the transducer through a relay. The relay is enabled and disabled by the controller and in the disabled state the energy storage device is allowed to accumulate energy. The energy is stored in the energy storage at a variable voltage level. The controller includes a component for determining a voltage level corresponding to an acceptable confidence level for echo pulses. The controller includes another component for determining a voltage level an increased response time.

Abstract: An ultrasonic sensor includes a piezoelectric vibrator, a reverberation measuring device and a compensating device. The piezoelectric vibrator vibrates to transmit an ultrasonic wave, receives a reflected wave of the transmitted ultrasonic wave and produces an output signal corresponding to vibration of the piezoelectric vibrator. The reverberation measuring device measures a reverberation period of the piezoelectric vibrator from the output signal. The compensating device compensates for an operation characteristic of the piezoelectric vibrator in accordance with the measured reverberation period. Thus, the ultrasonic sensor can decrease a reverberation period, which may cause reduction in detection accuracy and impossibility of detection of an obstacle at a short distance.

Abstract: A liquid measurement system including interface apparatus for sharing the excitation and signal processing of an ultrasonic transonic transducer and temperature measuring device remotely located at a liquid container is disclosed. The interface apparatus includes a common conduction path coupled to both of the ultrasonic transducer and the temperature device for conducting first excitation signals to the ultrasonic transducer and the corresponding echo signals therefrom, and for conducting second excitation signals to the temperature measuring device and the response signals therefrom, and an interface circuit for governing the conduction of the first and second excitation signals over the common conduction path from their generating sources and for providing a balanced interface for receiving both of the echo signals and response signals from the common conduction path.

Abstract: Methods for reducing ringing of dual-function ultrasonic air-coupled transducers in which at least one electrical passive circuit is applied to the transducer. The circuit may be either a linear circuit or a non-linear circuit. Different circuits can be applied to the transducer when the transducer is in a transmission mode than when the transducer is in a reception mode.

Abstract: An acoustic device that places existing components in a damping pattern after transmitting an acoustic signal. In one embodiment, the device comprises a transistor bridge and an acoustic transducer. The transistor bridge is coupled between two predetermined voltages having a voltage difference, and the acoustic transducer is coupled between the arms of the transistor bridge. The transistor bridge enters a damping configuration after applying an excitation pattern to the acoustic transducer. In the damping configuration, the input terminals of the transistor bridge are preferably grounded. In applying the excitation pattern, the transistor bridge preferably applies the voltage difference to the acoustic transducer in alternate polarities. In a preferred embodiment, the acoustic transducer includes a transformer having a primary winding coupled between the arms of the transistor bridge, and further includes a piezoelectric crystal coupled to a secondary winding of the transformer.

Abstract: A transmit-receive (T-R) switch for achieving fast T-R switching times while ensuring that the signal strength of a received signal is not fully coupled. A differential amplifier and an inverting amplifier, both having a coupling resistor as an input is used so that nearly all of the input signal is sensed by an operational amplifier. This technique improves transducer voltage transfer (coupling) ratio from 15-24% to about 100%. The T-R switch architecture is preferably to short-range, single-transducer acoustic ranging systems.

Abstract: The present invention relates to an electroacoustic transducer where the voltage of a capacitive acoustic element is controlled by charging and discharging the charge of the element via an inductance (L) by fast switches (K1, K2). In the case energy unconverted into the acoustic energy of the transducer can be transferred to an energy storage of an electrical circuit formed by the inductance (L) and the capacitance (C1, C2, C0) during each control sequence and in this way the transducer can be made to operate with a good coefficient of efficiency.

Abstract: A transmit-receive (T-R) switch for achieving fast T-R switching times while ensuring that the signal strength of a received signal is not fully coupled. A differential amplifier and an inverting amplifier, both having a coupling resistor as an input is used so that nearly all of the input signal is sensed by an operational amplifier. This technique improves transducer voltage transfer (coupling) ratio from 15-24% to about 100%. The T-R switch architecture is preferably to short-range, single-transducer acoustic ranging systems.

Abstract: Methods for reducing ringing of dual-function ultrasonic air-coupled transducers in which at least one electrical passive circuit is applied to the transducer. The circuit may be either a linear circuit or a non-linear circuit. Different circuits can be applied to the transducer when the transducer is in a transmission mode than when the transducer is in a reception mode.

Abstract: An underwater detection apparatus comprises a transducer, a transmitter capable of generating transmitting signals of a plurality of respective frequencies and for generating a transmitting signal, a broadband trap circuit for transferring the transmitting signal fed from the transmitter to the transducer and for passing an echo signal fed from the transducer, a preamplifier for amplifying the echo signal fed from the broadband trap circuit, a mixer for converting an output of the preamplifier into a signal of a specific frequency, a filter for selectively passing the signal of only the specific frequency-band output from the mixer, a main amplifier for amplifying an output of the filter, an A/D converter for converting an output of the main amplifier into a digital form, and a display circuit for displaying the digitized output of the A/D converter on a monitor, wherein the preamplifier is of a low-gain type.

Abstract: The circuit and the method serve to transmit a transmission signal to a transducer and to receive a reception signal from the transducer. The transmitter and the receiver are each alternatively coupled to the transducer and decoupled from one another. The coupling and decoupling is thereby achieved by a total of three nonlinear two-terminal networks (Z1, Z2, Z3). The transmitter is connected to the transducer via a bipolar voltage limiter and the receiver is connected to the transducer via a bipolar current limiter.

Abstract: A wireless transmitter associated with a switched electrical connection and a receiver therefor, adapted for connection in an electrical path between the source of power and a load, enables the load to be controlled by the switch originally used to control the switched electrical connection. The communication between the transmitter and receiver may be realized only when power is applied or removed from the switched connection, or, alternatively, this communication may be carried out on a per-cycle basis, enabling a phase-delay type of control over the relocated load, including dimming of the relocated load without requiring modification to a previously installed dimmer switch. The signal radiated by the transmitter may be of acoustic or electromagnetic origin, though IR transmissions are used in the preferred embodiment.

Abstract: A wireless boundary monitor system used to monitor the integrity of a boundary surrounding an area uses at least two housings having at least one transmitting means for emitting ultrasonic pressure waves to a medium. Each of the housings has a plurality of receiving means for sensing the pressure waves in the medium. The transmitting means and the receiving means of each housing are aimable and communicably linked. At least one of the housings is equipped with a local alarm means for emitting a first alarm indication whereby, when the pressure waves propagating from a transmitting means to a receiving means are sufficiently blocked by an object a local alarm means or a remote alarm means or a combination thereof emit respective alarm indications. The system may be reset either manually or automatically. This wireless boundary monitor system has useful applications in both indoor and outdoor environments.

Abstract: Intervals of timing pulses generated by a timing pulse generating means are changed by an interval changing means, interference signals from a second vibrator having the same intervals of the timing pulses being eliminated by changing the interval of the timing pulses by the interval changing means.

Abstract: A pulse transmitter for terminating reflected waves is disclosed which utilizes a series switched charged line pulse generator with a shunt element that is switched into the circuit immediately after the pulse is launched into an output line. The shunt element terminates any reflected wave so that it does not go back into the output line. The shunt element is formed by an optically controlled PIN diode coupled in series to a resistor which allows the circuitry to turn on fast and to handle high voltage pulses. The shunt element can be connected to either the input end of the charge line for circuitry embodiments in which the series switch stays closed or the shunt element can be connected at the output side of the series switch for embodiments in which the series switch opens after the pulse is formed such as, for example, where an avalanche switch is used.

Abstract: A transformer used to connect an electro-acoustic transducer to a transmitter and a receiver in a pulse-echo ranging system has a first winding connected to the transducer, and second and third windings connected in parallel to the transmitter and the receiver. The second winding has back-to-back diodes in series with it, and the third winding has several times more turns than the second winding, so that with high amplitude signals, as during transmission, the diodes conduct and render the second winding effective. With low amplitude signals, as during reception, the diodes isolate the second winding and the third winding acts to provide a relative step-up of the amplitude of the received signals.

Abstract: A continuous wave ultrasonic tracking system using an ultrasonic transmitter acoustically radiating a continuous wave ultrasonic transmitted signal and an ultrasonic receiver detecting the transmitted signal as a received signal. The system mixes the transmitted and received signals to create an interference pattern characterized by interference fringes, counts the number of the fringes by which the pattern changes with respect to a fixed point and stores the number as a number of wavelengths of the displacement between the transmitter and receiver, interpolates a location of the fixed point between successive ones of the interference fringes as a fraction of a wavelength and stores the fraction of a wavelength and computing the displacement by combining the number of wavelengths and the fractional number of wavelengths.

Abstract: An ultrasonic detector of the type for determining the level of a liquid within a tank or the magnitude of the flow of liquid within a conduit. The detector includes a transducer that generates bursts of ultrasonic energy and receives echoes of the energy bursts. The frequency at which the transducer transmits energy bursts is automatically adjusted to substantially match the ringdown frequency of the transducer. The detector distinguishes between true echo signals and spurious echo signals by determining whether the frequency of the echo signals generated by the transducer substantially matches the frequency at which the corresponding energy bursts were transmitted.

Abstract: Apparatus and method for determining the condition of the floor to be cleaned by a cleaning robot. The apparatus comprises an ultrasonic wave signal transmitting circuit for transmitting an ultrasonic wave signal to an ultrasonic wave signal transmitter under the control of a microcomputer, a receiving amplifying unit for amplifying the ultrasonic wave signal transmitted from the ultrasonic wave signal transmitter and received in a ultrasonic wave signal receiver, a receiving demodulating unit for smoothing the output signal from the receiving amplifying unit to demodulate it and then apply it to the microcomputer. According to the control of the microcomputer, the ultrasonic wave signal is transmitted for a predetermined period. The period from the time when the ultrasonic wave signal is transmitted to the time when the ultrasonic wave signal is received in the ultrasonic wave signal receiver is measured.

Abstract: An ultrasonic detector of the type for determining the level of a liquid within a tank or the magnitude of the flow of liquid within a conduit. The detector includes a transducer that generates bursts of ultrasonic energy and receives echoes of the energy bursts. The frequency at which she transducer transmits energy bursts is automatically adjusted to substantially match the ringdown frequency of the transducer. The detector distinguishes between true echo signals and spurious echo signals by determining whether the frequency of the echo signals generated by the transducer substantially matches the frequency at which the corresponding energy bursts were transmitted.

Abstract: In an acoustic pulse-echo ranging system, a high impedance piezoelectric transducer element is connected via a transformer to a transmitter, and also directly to a high impedance input of a receiver through a network, in parallel with the transducer element which includes a limiting resistor having a value which is low compared with the impedance of the transducer and a pair of oppositely connected diodes connected across the receiver input, the diodes being in series with the resistor and conducting to complete a damping circuit for large amplitude signals during transmission, and to limit the amplitude of signals applied to the receiver.

Abstract: An ultrasonic unipolar pulse/echo instrument uses active switches and a timing and drive circuitry to control electrical energy to a transducer, the discharging of the transducer, and the opening of an electrical pathway to the receiving circuitry for the returning echoes. The active switches utilize MOSFET devices along with decoupling circuitry to insure the preservation of the unipolar nature of the pulses, insure fast transition times, and maintain broad band width and time resolution. A housing contains the various circuitry and switches and allows connection to a power supply and a movable ultrasonic transducer. The circuitry maintains low impedance input to the transducer during transmitting cycles, and high impedance between the transducer and the receiving circuit during receive cycles to maintain the unipolar pulse shape. A unipolar pulse is valuable for nondestructive evaluation, a prime use for the present instrument.

Abstract: This switch device for detecting an object comprises a transducer for emitting and receiving ultrasonic signals to and from an object, a transmitter for driving the transducer, a receiver for receiving a signal from the transducer, a gate for detecting a short-distant object, a gate for detecting a long-distant object, and a circuit for setting the timings of the gates in accordance with the detecting ranges of the object.

Abstract: An ultrasonic transmission-reception system having a piezoelectric transducer for at least transmitting ultrasonic waves, a current generator for exciting the transducer so that it transmits an ultrasonic wave and electronic processing means able to determine in an approximate manner and store at least one current generator exciting signal. The exciting signal being associated with a reference object and leads to a predetermined detected ultrasonic wave shape from said object following the interaction of said object with the ultrasonic wave produced by the transducer as a result of the excitation of the current generator.

Abstract: An acoustic sensor functioning as a digital logic device comprises a resonant chamber, at least one port establishing a first resonant frequency therein when the port is closed and establishing a second resonant frequency therein when the port is open, a transmitter in communication with the chamber and tuned to either of the first or second resonant frequencies and a receiver in communication with the chamber for providing a digital logic output. When the port is closed or open and when the transmitter is tuned to the second or first resonant frequencies, respectively, the device functions as an inverter.

Abstract: A remote-control system for closures with a movable hand transmitter with at least one transmission key, this transmitter generating and radiating directed coded control signals upon actuation of the transmission key of the hand transmitter. At least one first receiver unit is tuned to receive the control signals radiated from the hand transmitter and is arranged on a motor vehicle and triggers switching effects on a remotely controllable vehicle locking after the received control signals have been identified as acceptable. At least one second receiver unit is tuned to receive control signals radiated as a result of the actuation of the transmission key of the hand transmitter for remotely controlling a remotely controllable access control device external to the motor vehicle. This second receiver unit is arranged outside the motor vehicle and triggers switching effects on the access control device after the received control signals have been identified as acceptable.

Abstract: A driver circuit for an acoustic transducer includes a voltage regulator that provides a regulated DC output level for a high value load impedance and when the load impedance falls to a low value, its DC output exhibits a substantially reduced level. A transformer is connected between the voltage regulator and the acoustic transducer. A switching circuit is connected to the transformer and is responsive to a leading edge of a pulse input signal to reflect a low value impedance through the transformer to the voltage regulator. The switching circuit is further responsive to a lagging edge of a pulse input signal to reflect a high value impedance to the voltage regulator. A capacitive reactance circuit is coupled to the transformer and is responsive to the switching circuit reflecting a low value impedance to manifest a reduced charge state.

Abstract: Linear and switching amplifiers associated with acoustic transducers requ a gradual turn-on rather than an abrupt full-power level signal. A transducer preamplifier power controller circuit prevents the operation of fuses and the tripping of circuit breakers when the relatively high power driving levels for a sonar transducer are initiated. The controller circuit gradually increases a signal level from a zero level to a maximum during the initiation of a sonar signal using a threshold level that is set to a fraction of the expected maximum, and two discrete clock frequencies, for example at 1 MHz and 2 KHz actuate interconnected digital control elements incrementally to increase the signal level during a predetermined period. This cycle is re-initiated by the next sonar signal.

Abstract: An optical ranging system includes optics that create a backscatter signal in response to a transmitted light pulse. The transmitted pulse is reflected from a target to provide range information. The backscatter signal is applied to trigger a threshold detector. The output of the threshold circuit is applied to a delay circuit to provide a receiver switch control signal which renders a receiver switch conductive after the backscatter signal. Accordingly, the receiver switch blanks the backscatter signal and applies the reflected signal to the receiver.

Abstract: A switch device is disclosed for detecting an object which comprises a transducer for emitting and receiving ultrasonic signals to and from an object, a transmitter for driving the transducer, a receiver for receiving a signal from the transducer, a gate for detecting a short-distant object, a gate for detecting a long-distant object, and a circuit for setting the timings of the gates in accordance with the detecting ranges of the object.

Abstract: A detection system forms a plurality of reception beams successively in angular directions by receiving incoming signals from various directions in a manner that the Doppler effect is produced to vary the carrier frequency of the incoming signals. The detection system displays underwater conditions on an indicator. To determine the underwater conditions, the detection system uses a plurality of ultrasonic transducers for receiving incoming signals, a plurality of preamplifiers for amplifying the reception signals produced by the ultrasonic transducers. A first coupling device which connects at least two of the ultrasonic transducers to a single preamplifier, and a matched filter for pulse-compressing reception signals produced by the ultrasonic transducers. A second coupling device successively couples the output terminals of the preamplifiers to an input terminal of the matched filter. The indicator displays output signals from the matched filter.

Abstract: An ultrasonic imaging apparatus includes an ultrasonic transducer for outputting an ultrasonic beam and converting the echo of the ultrasonic beam into an echo signal, a transmitter section for supplying a drive signal to the ultrasonic transducer, a receiver section for receiving the echo signal output from the ultrasonic transducer and converting the echo signal into an image signal, and a coaxial cable for coupling the ultrasonic transducer to the transmitter and receiver sections. The ultrasonic transducer is constituted by a two-layer ultrasonic transducer having an impedance smaller than an impedance of the coaxial cable.

Abstract: An echo canceller in a system, having a long impulse response such as in an acoustic system, which employs a fast Fourier transform to transform input data represented in the time domain into signals represented in the frequency domain to reduce calculations. To solve the problem of a long delay, the impulse response length is divided into a plurality of blocks. Each block then has a decreased number of samples within each block. Thus, a fast Fourier transform and finite impulse response type digital filtering are effected, so that the processing delay is decreased while the amount of calculations is kept small.

Abstract: A three-phase generator is used to directly drive an array of electroacoustic transducers without the usual high power amplifiers. Complex signals having general spectra are generated by driving the generator rotor field with an excitation comprised of in-phase and quadrature components. These components are appropriately transformed so that a readily available three-phase wound rotor machine can be used without modification. The three output phases of the generator are connected to a multi-tapped delta connected transformer. Appropriate tap connection for each transducer allows achieving the desired voltage and phase angle. Freedom in choosing taps simultaneously allows balancing of the generator load.

Abstract: An ultrasonic imaging apparatus comprises an ultrasonic probe, a transmitter/receiver circuit for driving the ultrasonic probe to emit an ultrasonic beam and processing an echo signal output from the ultrasonic probe and junction unit coupled between the ultrasonic probe and the transmitter/receiver circuit and including an impedance transforming circuit having a high input impedance and a low output impedance for taking in an echo signal output from the ultrasonic probe at high impedance and outputting the taken-in echo signal at low impedance.

Abstract: An ultrasonic distance sensor transmitting from and receiving an ultrasonic wave with a single ultrasonic transmitting and receiving element to measure proximate distances such as vehicle floor heights or distances to obstacles or pedestrians approaching relative to a vehicle. The ultrasonic transmitting and receiving element is accommodated by means of a resilient member having beads, under pressure in a casing and secured therein, thus attenuating residual vibration which disturbs accurate measurement of the proximate distances. The beads also serve to prevent water from invading into the case. The sensor incorporates a protection circuit for preventing burn-out of an output transistor due to accidental prolonged transmission.

Abstract: A wireless transmitter associated with a switched electrical connection and a receiver therefor, adapted for connection in an electrical path between the source of power and a load, enables the load to be controlled by the switch originally used to control the switched electrical connection. The communication between the transmitter and receiver may be realized only when power is applied or removed from the switched connection, or, alternatively, this communication may be carried out on a per-cycle basis, enabling a phase-delay type of control over the relocated load, including dimming of the relocated load without requiring modification to a previously installed dimmer switch. The signal radiated by the transmitter may be of acoustic or electromagnetic origin, though IR transmissions are used in the preferred embodiment.