Abstract: Improvements to a method for imaging a target, which method including the steps of (a) transmitting ultrasonic energy at a fundamental frequency, (b) receiving reflected ultrasonic energy at a harmonic of the fundamental frequency and (c) generating an image responsive to reflected energy at the harmonic, are provided. The transmitting step includes transmitting a waveform with a positive pulse spatially defined by first and second zero values. A positive peak amplitude of the positive pulse is a first distance from the first zero value that is less than half a second distance between said first and second zero values. Thus, the waveform includes a fundamental spectral component and a harmonic spectral component at the transducer. An attenuation normalized peak of the harmonic spectral component is reduced at a region spaced from the transducer as compared to the peak at a region adjacent to the transducer. A negative peak is also shifted or pre-distorted.

Abstract: A system (100) and method (200) for adaptively managing bias of an RF power amplifier (102) is provided. The system (100) incorporates a controller (116) configured to select a radio operating mode. A current-mirror circuit (114) is coupled to the controller (116) and configured to produce a reference current (IRef) as a function of the radio operating mode. A bias regulator (104) is coupled to the controller (116) and the current-mirror circuit (114) and configured to produce a driver-stage bias current (Ib1) and an output-stage bias current (Ib2) for the power amplifier (102) in response to the reference current (IRef). The system (100) also incorporates a DC-to-DC converter (118) coupled to the controller (116) and configured to provide a supply voltage (Vcc) for the power amplifier (102) in response to the radio operating mode. The system (100) also incorporates an envelope detector (120) configured to produce an envelope current (IEnv) in response to an RF input signal (126).

Abstract: A receiver including an analog Barker detector including digital processing logic, a radio and an analog-to-digital converter (ADC). The digital processing logic has a receive signal input for processing digital baseband signals and a power activation input for receiving a detection signal. The radio receives and converts radio frequency (RF) signals into analog baseband signals, and includes a Barker matched filter coupled to receive the analog baseband signals, an envelope detector, a peak detector, and a counter circuit. The counter circuit detects Barker signals and provides the detection signal for powering up the digital processing logic. The digital processing logic is powered down between signal acquisitions to conserve power and powers up in response to the detection signal. The ADC may also be powered up and down in a similar manner to conserve additional power.

Abstract: A power amplifier linearizer (12) includes an on-chip portion (60) and an external controller (22). The on-chip portion (60) implements two predistortion circuits (86, 88) desirably configured as look-up tables. One predistortion circuit (88) is programmed by the external controller (22) to apply a hotter linearizing translation function (54) and the other predistortion circuit (86) is programmed by the external controller (22) to apply a colder linearizing translation function (56). One or more temperature signals (24, 38) are correlated with the temperatures experienced by a power amplifier (34) and drive a power amplifier thermal modeler (50) implemented in the controller (22). As a result of running the thermal modeler (50), the controller (22) generates an interpolation signal (26) that indicates how far to interpolate between the hotter and colder translation functions (54, 56).

Abstract: A power amplifier linearizer (12) includes an on-chip portion (60) and an external controller (22). The on-chip portion (60) implements two predistortion circuits (86, 88) desirably configured as look-up tables. One predistortion circuit (88) is programmed by the external controller (22) to apply a hotter linearizing translation function (54) and the other predistortion circuit (86) is programmed by the external controller (22) to apply a colder linearizing translation function (56). One or more temperature signals (24, 38) are correlated with the temperatures experienced by a power amplifier (34) and drive a power amplifier thermal modeler (50) implemented in the controller (22). As a result of running the thermal modeler (50), the controller (22) generates an interpolation signal (26) that indicates how far to interpolate between the hotter and colder translation functions (54, 56).

Abstract: Improvements to a method for imaging a target, which method including the steps of (a) transmitting ultrasonic energy at a fundamental frequency, (b) receiving reflected ultrasonic energy at a harmonic of the fundamental frequency and (c) generating an image responsive to reflected energy at the harmonic, are provided. The transmitting step includes transmitting a waveform with a positive pulse spatially defined by first and second zero values. A positive peak amplitude of the positive pulse is a first distance from the first zero value that is less than half a second distance between said first and second zero values. Thus, the waveform includes a fundamental spectral component and a harmonic spectral component at the transducer. An attenuation normalized peak of the harmonic spectral component is reduced at a region spaced from the transducer as compared to the peak at a region adjacent to the transducer. A negative peak is also shifted or pre-distorted.

Abstract: Improvements to a method for imaging a target, which method including the steps of (a) transmitting ultrasonic energy at a fundamental frequency, (b) receiving reflected ultrasonic energy at a harmonic of the fundamental frequency and (c) generating an image responsive to reflected energy at the harmonic, are provided. The transmitting step includes transmitting a waveform with a positive pulse spatially defined by first and second zero values. A positive peak amplitude of the positive pulse is a first distance from the first zero value that is less than half a second distance between said first and second zero values. Thus, the waveform includes a fundamental spectral component and a harmonic spectral component at the transducer. An attenuation normalized peak of the harmonic spectral component is reduced at a region spaced from the transducer as compared to the peak at a region adjacent to the transducer. A negative peak is also shifted or pre-distorted.

Abstract: A medical diagnostic ultrasonic imaging method and system subdivide the transmit aperture into two or more subapertures, each subaperture having at least four adjacent transducer elements. The subapertures are phased differently with respect to one another to selectively reduce either fundamental components or harmonic components of echoes from tissue. These techniques can be used to improve contrast agent harmonic imaging as well as tissue harmonic imaging, depending upon the phase shift selected.

Abstract: An improvement to the method for harmonic imaging including the steps of (a) transmitting ultrasonic energy at a fundamental frequency and (b) receiving reflected ultrasonic energy at a harmonic of the fundamental frequency is provided. The transmitting step includes the step of: applying the plurality of waveforms to a respective plurality of transducer elements, a first waveform of the plurality of waveforms characterized by a first value of a harmonic power ratio, waveforms transmitted from the transducer elements and corresponding to the plurality of waveforms summing as an acoustic waveform substantially at the point, the acoustic waveform characterized by a second value of the harmonic power ratio less than the first value. The imaging method can also include a step for subdividing the transmit aperture into two or more subapertures, each subaperture having at least four adjacent transducer elements.

Abstract: An improvement to the method for harmonic imaging including the steps of (a) transmitting ultrasonic energy at a fundamental frequency and (b) receiving reflected ultrasonic energy at a harmonic of the fundamental frequency is provided. For the improvement, the transmitting step includes the step of transmitting a uni-polar waveform or a waveform characterized by an amplitude change rate of 8 or fewer times pre carrier cycle, said waveform comprising an envelope shape rising gradually to a respective maximum value and falling gradually from the respective maximum value.

Abstract: An ultrasound imaging method includes the step of transmitting two ultrasonic transmit pulses into a region. First components of the transmit pulses are inverted with respect to each other while second components of the transmit pulses are not. Received ultrasound pulses associated with the transmit pulses are summed to selectively cancel the harmonic or fundamental components. By properly selecting the inverted and noninverted portions of the transmit pulses, the transmit pulses may be made unipolar, or they may be pre-distorted to further reduce second harmonic energy associated with system or tissue non-linearities.

Abstract: A real-time magnetic digital video disk recording system has been developed for applications in on-line digital imaging systems and off-line fast access image storage and retrieval buffers. The disk recorder uses new high density recording technology and Winchester computer drive technology in a unique peripheral configuration which is fully synchronized to video system timing, provides for flexible formatting, achieves fast random access to a large video image file, and eliminates the need for complex data controllers. The recorder includes two independent actuator and head assemblies for alternately recording successive video fields on separate tracks on separate zones A and B of a disk stack. Movement of one of the actuators and head assemblies is controlled and occurs within a field time to skip tracks containing media flaws to achieve real time digital video recording.

Abstract: A real-time magnetic digital video disk recording system has been developed for applications in on-line digital imaging systems and off-line fast access image storage and retrieval buffers. The disk recorder uses new high density recording technology and Winchester computer drive technology in a unique peripheral configuration which is fully synchronized to video system timing, provides for flexible formatting, achieves fast random access to a large video image file, and eliminates the need for complex data controllers. The recorder includes two independent actuator and head assemblies for alternately recording successive video fields on separate tracks on separate zones A and B of a disk stack. Movement of one of the actuators and head assemblies is controlled and occurs within a field time to skip tracks containing media flaws to achieve real time digital video recording.

Abstract: An AGC amplifier having a fast response for recovery and reacquisition of gain control in microseconds after a signal break including a first and second amplifiers interconnected by a delay line equalizer. An integrator control loop is responsive to the output of the second amplifier and is connected to the control means provided on the first amplifier and includes a feedback loop having a peak detector, an ideal integrator connected to the output of the peak detector and directly controlling the first amplifier using an ideal integrator capacitor loop during control operation and having a switch removable reset loop for operating as a fixed high gain amplifier in the absence of signal. The latter is determined by a comparator operating to receive a second peak detector signal not in the control loop.

Abstract: High resolution video signals of bandwidth up to 25 mHz are recorded magnetically or optically, or are transmitted on a communications channel carrier with superior fidelity by using novel electronic circuit system including implementations of an FM modulator, writing amplifier, and wideband discriminator which enable coding and decoding with high accuracy, low noise, and low interference. The video signals are used to directly modulate a square wave carrier using an FM technique employing a very low center frequency-to-bandwidth ratio without need for subsequent frequency translations. A writing amplifier provides gain needed for saturated recording with unique provisions to balance transition amplitudes for minimum second harmonic distortion without affecting the primary phasing of transitions. A novel multiwinding inductor and pulse discriminator implementation is capable of demodulating the very wide deviation FM signal with good cancellation of the second harmonic and fundamental FM carrier spectrums.