Abstract: Systems and methods for improving transducer response sensitivity in an ultrasound-imaging system are disclosed. One method includes selecting a desired transmit spectrum, quantifying the transmit channel impulse response, calculating a drive signal that when applied to the transmit channel will produce the desired transmit spectrum and applying the drive signal to the transducer. The method may be applied in principle to the receive channels. An improved ultrasound-imaging system in accordance with the invention includes a transducer and a switch controlled to apply an excitation signal to the transducer in a transmit mode of the ultrasound-imaging system. A signal shaper is configured to generate an excitation signal in response to the impulse response of the transmit channel such that a desired ultrasound energy waveform is generated by the transducer. An adaptable filter responsive to a desired echo spectrum and the impulse response of the receive channel of the system may be included.

Abstract: Systems and methods for improving transducer response sensitivity in an ultrasound-imaging system are disclosed. One method includes selecting a desired transmit spectrum, quantifying the transmit channel impulse response, calculating a drive signal that when applied to the transmit channel will produce the desired transmit spectrum and applying the drive signal to the transducer. The method may be applied in principle to the receive channels. An improved ultrasound-imaging system in accordance with the invention includes a transducer and a switch controlled to apply an excitation signal to the transducer in a transmit mode of the ultrasound-imaging system. A signal shaper is configured to generate an excitation signal in response to the impulse response of the transmit channel such that a desired ultrasound energy waveform is generated by the transducer. An adaptable filter responsive to a desired echo spectrum and the impulse response of the receive channel of the system may be included.

Abstract: Systems and methods for improving transducer response sensitivity in an ultrasound-imaging system are disclosed. A preferred method generally includes the steps of: selecting a desired transmit spectrum; quantifying the transmit channel impulse response; calculating a drive signal that when applied to the transmit channel will produce the desired transmit spectrum; and applying the drive signal to the transducer. Other methods include selecting a desired echo response spectrum; quantifying a receive channel impulse response; formulating a filter that when applied to received ultrasound echo signals will produce the desired echo response spectrum; and applying the filter.

Abstract: An ultrasound imaging device having a bipolar transmitter to generate a bipolar voltage signal, a transducer to emit an ultrasound wave in response to the bipolar voltage signal, and a bias generator to bias the bipolar voltage signal prior to being received by the transducer so that the biased bipolar voltage signal maintains a same polarity as a poling polarity of the transducer throughout a transmit cycle of the ultrasound imaging device. By biasing the bipolar voltage signal to maintain a same polarity as the poling polarity of the transducer throughout the transmit cycle, the ultrasound imaging device prevents depoling of the transducer which could otherwise occur if the transducer is driven by a bipolar voltage signal which repeatedly has a polarity opposite to the poling polarity of the transducer.

Abstract: An arbitrary waveform generator includes an arithmetic element that can access samples from a waveform sample memory and adjust values accessed from the waveform sample memory to modify waveform power or amplitude. In an illustrative embodiment of the arbitrary waveform generator, the arithmetic element is a multiplying digital-to-analog converter (DAC) that has a first input connection for receiving digitized waveform samples and has a second input connection for receiving a reference signal. An output signal from the multiplying DAC is a mathematical product of the digitized waveform samples and the reference signal. In one example, a reference digital-to-analog converter (DAC) generates the reference signal. In some examples, the digitized waveform samples are digitized samples of an analog waveform signal. In some examples, the arithmetic element is incorporated into the arbitrary waveform generator in a manner to maintain transmit signal resolution over a full range of transmit power settings.

Abstract: A method and system for compensating for steering anomalies by adjusting aperture in steered phased array transducer systems adjusts the aperture of a transducer array to effectively compensate for the steering anomalies. The aperture of the transducer array can be varied depending upon the steering angle of the beam and the resultant steering angle anomalies.

Abstract: This invention relates to a circuit for detecting the phase of an AC signal of frequency f. The signal is applied to two mixers one of which mixes the AC signal with a first signal of frequency f to generate a signal I and the other of which mixes the AC signal with a second signal of frequency f which is 90 degrees out of phase with the first signal to generate a signal Q. The I and Q signals are digitized and the log of the absolute value of each of the digitized signals is generated. The log generating function may for example be performed with a table-look-up memory. One log value, for example log I, is substracted from the other log value and the Arctan of the antilog of this difference is then generated. The Arctan function may also be generated using a table-look-up memory. The resulting Arctan value is indicative of the phase of the AC signal.

Abstract: Ventricular ectopic heartbeats are detected by comparing the ECG wave for a current heartbeat with the ECG wave of a heartbeat considered to be normal for that patient. The waves are aligned with their fiducial points in time coincidence, and the fiducial points are located at the centroids of the ECG waves.

Abstract: Special circuitry in the transmitter of an electrocardiograph (ECG) telemetry system detects various malfunctions of the system and changes the transmitted signal to indicate their presence to the system receiver. When the transmitter detects that an input electrode has become detached from the patient, it changes the frequency of the subcarrier signal to indicate this problem to the receiver. The receiver monitors the subcarrier frequency and flashes an alarm light when the frequency corresponds to the electrode inoperative condition.