US Patent No. 5,873,836 February 23, 1999
A method and apparatus is provided for distinguishing blood pressure sounds from noise in an automatic blood pressure monitoring system using the information contained in two microphone signals. Two microphones are placed on a patient along an axis of an artery to pick up blood pressure sounds. Pressure is applied to the artery such that the artery opens and closes during each heart cycle, the opening snap of the artery producing a blood pressure sound. The two microphone signals are sampled, filtered, and multiplied together to produce a microphone signal product. The microphone signal product is wave width filtered to remove therefrom portions of the signal having a wave width which is less than a selected minimum wave width value. A blood pressure sound is indicated as being detected when an amplitude of this wave width filtered microphone signal product exceeds a noise signal threshold level. The microphone signal product is also wave width filtered to remove therefrom portions of the signal having a wave width which is greater than a selected maximum wave width value. The amplitude of the resulting noise amplitude signal is used to adjust dynamically the noise signal threshold level in response to changing noise conditions. The detection of blood pressure sounds at a range of applied pressure levels is used to determine the systolic and diastolic blood pressure levels of the patient.
US Patent No. 6,339,715 B1 January 15, 2002
US Patent No. 6,647,280 B2 November 11, 2003
A signal processing method, preferably for extracting a fundamental period from a noisy, low-frequency signal, is disclosed. The signal processing method generally comp rises calculating a numerical transform for a number of selected periods by multiplying signal data by discrete points of a sine and a cosine wave of varying period and summing the results. The period of the sine and cosine waves are preferably selected to have a period substantially equivalent to the period of interest when performing the transform.
US Patent N0. US 6,308,089 B1 October 23, 2001
US Patent No. US 7,048,687 B1 May 23, 2006
A limited use medical probe is disclosed including a memory for maintaining a use value. The medical probe is coupled to a medical device that inhibits its function when the use value reaches a predetermined threshold value, preventing improper use of the probe. The probe memory may also store identification, usage, and clinical data. A probe auto-identification function, a probe re-identification function and a probe functional test sequence are disclosed for the medical probe. After use, a reprocessing step may reset the probe memory, permitting further probe use.
Publication N0. US 2011/0108438 A1 May 12, 2011
The invention herein provides an apparatus and method of controlling an electrochemical treatment process where treat ment is performed in a flow cell to ensure that a controlled dose of electrical energy or current is delivered to all volumes of the liquid being treated. In addition the invention provides for further optimization of the dose based on other factors and
sensor inputs. This invention also provides a method to estimate, display and record a forecast of process efficacy such as disinfection, oxidation or other desired treatment that otherwise cannot be measured in an online manner.
Patent N0. US 9,161,430 B1 October, 13, 2015
A Helical Resonator Ion Accelerator in which ions are injected into a hollow dielectric pipe forming a vacuum chamber along which the ions are accelerated. The pipe is wrapped with a coil and positioned inside a metal pipe. The dielectric pipe, the coil and the metal pipe are arranged coaxially on an axis along which ions are accelerated. The metal pipe is positioned within a high intensity 0.5-3.0 Tesla solenoid. A pulse generator is coupled to the coil to generate a voltage wave pulse. The pulse travels down the axis of the accelerator on the helix formed by the coil. An ion source injects deuteron ions along the axis of the vacuum chamber. A traveling voltage wave is accelerated by tapering the characteristic velocity of the accelerator in the direction of wave propagation by tapering the coil and the outer metal pipe together in a constant ratio.
US Patent No. 3,926,179 December 16, 1975
This invention provides apparatus for accurately measuring and continuously monitoring blood pressure. The apparatus comprises a blood pressure probe adapted to engage a body member such as one arm of the patient. The probe includes a pressure applying member for engaging the surface of the body member over an artery which is near the surface. For example, the pressure applying member may be located over the radial artery in the wrist of the patient’s arm. The probe also includes pressure exerting means, such as a solenoid, for pressing the pressure applying member against the surface of the body member, so as to produce partial flattening of the artery. The pressure app lying member includes a pressure sensor adapted to engage the surface of the body member over the artery for sensing the blood pressure pulses in the artery. The sensor includes a transducer for producing electrical signals corresponding to the blood pressure pulses. The apparatus includes control means for operating the pressure exerting means to maximize the electrical signals corresponding to the pulse pressure. For example, a feedback circuit may be provided to energize the solenoid to such an extent as to maximize the pulse pressure signals. Generally, the signals will be maximized when the artery is flattened approximately halfway. The true or corrected waveform of the blood pressure signals may be derived and displayed on an oscilloscope for continuously monitoring the blood pressure variations. Means may also be provided for deriving and indicating the systolic and diastolic blood pressure values, and also the pulse pressure. The blood pressure measuring apparatus is highly accurate, continuous in operation, and noninvasive, in that it is not necessary to invade the artery. Moreover, the function of the artery is not impaired, since the device is nonocciusive. The blood pressure probe, together with the supporting apparatus, is called a tonometer.
US Patent No. 4,441,357 April 10, 1984
A closed pressure monitoring system is disclosed in which a pump delivers gas on a supply line through a first accumulator chamber to a load device and returns the gas on a return line through a second accumulator chamber to the pump. After pressures in the first and second chambers stabilize, the pressures are compared, and a leak warning signal is given if the compared pressures changed with respect to one another over time. The system is particularly adapted to use a pressure sensor as the load which is implanted within a human patient. The pressure sensor receives air from a restrictor in the supply line and is operative to maintain the pressure in the supply line substantially equal to the pressure surrounding the sensor.
US Patent No. 4,796,184 January 3, 1989
The device measures blood pressure automatically using the oscillometric technique. The device includes a pressure cuff which is automatically inflated to an initial pressure which is calculated to be above the subject’s systolic pressure. The cuff is then deflated stepwise in preset pressure increments while cuff pressure oscillations are sensed at each cuff pressure level and stored in a computer incorporated into the device, Cuff deflation is continued until the cuff pressure is below the subject’s diastolic pressure whereupon the cuff is automatically deflated. The computer then fits a calculated parabolic curve onto the greatest cuff pressure oscillation and onto a lesser oscillation on each side of the greatest oscillation. From the thusly derived curve, the computer determines the mean blood pressure, and the systolic and diastolic blood pressures.
US Patent No. 4,814,771 March 21, 1989
A radio signal containing Loran C pulses from stations of interest is received and periodically sampled to convert the input signal to sample data. The data is assigned to memory locations within an acquisition memory at positions in the memory which correspond to specific times within the group repetition interval (GRI) of the Loran chain of interest. A GRI counter assigns the locations in the memory to which the data are written and cycles the memory after the completion of each CR1 so that new data corresponding to a new set of pulses from the master and secondary stations of the Loran C chain will be assigned to essentially the same memory locations as data acquired during a previous CR1. The new data is ensemble averaged with the old data contained in the memory locations and the averaged data stored back in the memory. As data is collected and averaged over a sufficient number of GRI’s, any signals present in the received radio signal which are not synchronous with the GRI will tend to be avers aged out, improving the signal to noise ratio of the Loran C pulses in the memory. Averaging of the sampled input signal over several GRI’s in this manner minimizes the effect of sporadic noise, continuous wave interference and cross rate interference. After completion of the averaging process, the data in the acquisition memory may be searched to determine the time differences between the master and secondary pulses in a manner normally carried out in Loran C receivers.
US Patent No. 4,875,019 October 17, 1989
A preamplifier system adapted for a Loran receiver includes a buffer amplifier receiving the signal from the antenna at its input and a tuned circuit connected between the input of the buffer amplifier and ground. The tuned circuit includes a parallel combination of a resistance, capacitance and inductance with values selected such that a resonant frequency is provided substantially at or near the carrier frequency of the Loran signal to pass it while higher and lower frequencies, constituting extraneous noise signals, are substantially attenuated. In particular, low frequency, e.g. 60 Hz signals and DC from sources such as precipitation static, are shunted to ground through the parallel inductor in the tuned circuit so that these low frequency components do not affect the performance of the receiver. A secondary filter section is connected to the output of the buffer amplifier and has components that may be selected in value such that the overall transfer function of the preamplifier, including the tuned input circuit, has a desired bandpass characteristic. Thermal noise contributed by the parallel resistor in the tuned circuit may be reduced by feeding back the output of the buffer amplifier through the resistor to effectively reduce its noise contribution while leaving the effective input resistance the same. Notch filters may be incorporated with the input tuned circuit to reject strong extraneous signals within the passband.