Method and device for controlling transmission power of an active transducer
First Claim
1. A device for controlling the transmission power of an ultrasound signal produced by an ultrasound transducer used to monitor fetal heart rate (FHR), the device comprising:
- a signal to noise ratio (SNR) calculator that receives a returned signal from an ultrasound transducer, the returned signal having passed through the body of a patient and computes an SNR for the returned signal;
a short term analysis (STA) template generator that receives the returned signal and creates an STA template from a short duration portion of the returned signal;
a long term analysis (LTA) template generator that receives the returned signal and creates an LTA template for which a number of correlation peaks is maximized by iteratively correlating successive templates over a long duration portion of the returned signal;
a template selector that selects between the LTA template and the STA template, and produces a control signal indicative of the selected template;
an FHR detector that cross correlates the selected template with the returned signal to determine an instantaneous fetal heart rate; and
a transmission power controller that receives the signal indicative of the selected template, selects a predefined optimal SNR range for the selected template, compares the computed SNR for the returned signal to the selected predefined optimal SNR range, and produces a control signal which is sent to the ultrasound transducer to modify the transmission power of the ultrasound transducer thereby modifying the SNR of the returned signal.
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Accused Products
Abstract
A method of operating an ultrasound signal generator includes generating a stimulus signal and receiving a returned signal. The Signal to Noise Ratio (SNR) of the returned signal is computed. The SNR is compared to an optimal SNR range. A control signal is generated to control the transmission power of the stimulus signal. A new stimulus signal is generated at the new transmission power. A device for collecting and analyzing a quasi-periodic signal includes a SNR calculator that computes the SNR of a returned signal. A signal analysis selector selects between a first and a second signal analysis technique. A transmission power controller compares the computed SNR with an optimal SNR range for the selected technique and modifies the transmission power as a result of this comparison.
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Citations
18 Claims
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1. A device for controlling the transmission power of an ultrasound signal produced by an ultrasound transducer used to monitor fetal heart rate (FHR), the device comprising:
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a signal to noise ratio (SNR) calculator that receives a returned signal from an ultrasound transducer, the returned signal having passed through the body of a patient and computes an SNR for the returned signal; a short term analysis (STA) template generator that receives the returned signal and creates an STA template from a short duration portion of the returned signal; a long term analysis (LTA) template generator that receives the returned signal and creates an LTA template for which a number of correlation peaks is maximized by iteratively correlating successive templates over a long duration portion of the returned signal; a template selector that selects between the LTA template and the STA template, and produces a control signal indicative of the selected template; an FHR detector that cross correlates the selected template with the returned signal to determine an instantaneous fetal heart rate; and a transmission power controller that receives the signal indicative of the selected template, selects a predefined optimal SNR range for the selected template, compares the computed SNR for the returned signal to the selected predefined optimal SNR range, and produces a control signal which is sent to the ultrasound transducer to modify the transmission power of the ultrasound transducer thereby modifying the SNR of the returned signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of operating an ultrasound signal generator, the method comprising:
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generating a stimulus signal with the ultrasounds signal generator at a transmission power; receiving a returned signal in response to the stimulus signal; creating a short term analysis (STA) template from a short duration portion of the returned signal; cross correlating a first template with a long duration portion of the returned signal to create a first correlation signal; counting peaks in the first correlation signal greater than a predetermined threshold; selecting portions of the long duration portion of the returned signal that correspond to the counted peaks; averaging the selected portions to create a second template; repeating cross correlating to create correlation signals, counting peaks in the correlation signals, selecting portions that correspond to the counted peaks, and averaging the selected portions in order to maximize the counted peaks; selecting an LTA template that maximizes the counted peaks; deriving an instantaneous fetal heart rate from the returned signal using one of the STA template or the LTA template; computing a signal to noise ratio (SNR) of the returned signal; selecting a predetermined optimal SNR range based upon whether the STA template or LTA template was used to derive the instantaneous fetal heart rate; comparing the SNR to the predetermined optimal SNR range; controlling the transmission power to maintain the SNR within the predetermined optimal SNR range. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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Specification