Blood Pressure Monitor block diagram and design considerations.
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Blood pressure monitors can use Korotkoff, Oscillometry, or Pulse Transit Time methods to measure blood pressure. They employ a pressure cuff, pump, and transducer to measure blood pressure and heart rate in three phases: Inflation, Measurement, and Deflation. They include an LCD, selection buttons, memory recall, power management, and USB interface.
The pressure transducer produces the output voltage proportional to the applied differential input pressure. The output voltages of the pressure transducer range from 0 to 40 mV, which need to be amplified so that the output voltage of the DC amplifier has a range from 0 to 5V. Thus, we need a high-gain amplifier. Then the signal from the DC amplifier will be passed on to the band-pass filter. The DC amplifier amplifies both DC and AC component of the signal. The filter is designed to have large gain at around 1-4 Hz and attenuate any signal that is out of the pass band. The AC component from filter is important for determining when to capture the systolic/diastolic pressures and heart rate of the patient. The final stage of the front end is an AC coupling stage, after which the signal is sent to analog to digital converters, and digitized.
The digital measurements of pressure and heart rate are performed by the microprocessor. Measurements results are stored in EEPROM or FLASH memory as a data log that can be uploaded to a PC via USB. The analog circuit is used to amplify both the DC and AC components of the output signal of pressure transducer so that we can use the MCU to process the signal and obtain useful information about the patient's health.
F ingerprint Biometric technology refers to the use of a person's fingerprint characteristics for identifying that person.
Fingerprint biometrics are used in a variety of applications including electronic door locks, smart cards, vehicle ignition control systems, USB sticks with fingerprint controlled access, and many others. Digital signal processing elements in fingerprint scanners perform complex DSP functions such as filters, transforms, feature extraction, matching operations and other algorithms.
Fingerprint sensors can use capacitive, optical, pressure, or thermal technologies to obtain an image of a finger’s features. The most common fingerprint sensor solution first illuminates the print with a laser or LED light and then captures the image using a CCD or less expensive CMOS sensor. Fingerprint sensors are typically self contained modules that include an analog to digital converter to translate the analog information into a digital data stream. Resolution, dynamic range and pixel density are factors that contribute to the image quality and influence the accuracy of the sensor.
Once the image is captured the digital information is transferred to a digital signal processor to generate a match. The first step in the matching process is conditioning the scanned fingerprint. Finger print readers rarely use the full fingerprint for identification. Rather, DSPs use algorithms to extract the unique features and patterns of each print to generate a unique digital code. The second step in the software flow is to take the code generated from the scanned image and compare it to a database of potential matches. The compare step requires the system to have access to print information in a networked database or a non-volatile memory unit.
2.3. CT Scanner (Компьютерный томограф)
Medical Imaging Solutions from Texas Instruments
Computed tomography (CT) is a medical imaging technique that produces three-dimensional images of internal human body parts from a large series of two-dimensional X-ray images taken around a single axis of rotation. When compared with a conventional X-ray radiograph, which is an image of many planes superimposed on each other, a CT image exhibits significantly improved contrast.
With the advent of diagnostic imaging systems like CT, where complex and intensive image processing is required, semiconductors play a very important role in developing systems with increased density, flexibility and high performance.
X-ray slice data is generated using an X-ray source that rotates around the object with X-ray detectors positioned on the opposite side of the circle from the X-ray source. The whole rotating structure is called gantry and every x-ray shot from a given angle is called profile. Of the order of 1000 profiles per revolution are taken progressively as the object is gradually passed through the gantry. The data acquisition system usually consists of a number of channel cards that have an array of scintillator-photodiode solid state detectors follow by the readout electronics.
Each photodiode produces a current proportional to the x-ray intensity that the pixel receives. Traditionally, the channel card has a front-end where the current from the detector is integrated and converted to digital values by ADCs. TI’s DDC products are single-chip solutions for Directly Digitizing low-level Currents from photodiode arrays in CT scanners. Each DDC channel provides a dual switched integrator front-end to process the current coming from one photodiode. This configuration allows for continuous current integration (avoiding any input signal loss): while one integrator output is being digitized by the on board A/D converter, the other is integrating the input current.
The digital data from all channel cards is transferred by high-speed link (LVDS interface) to the controller card and onto the image conditioning cards. The image conditioning card is connected to the host computer where the CT images can be viewed. Here, the digital data are combined by the mathematical procedure known as tomographic reconstruction.
Within the controller cards, TI DSPs with advanced VelociTI, very-long-instruction-word (VLIW) architecture developed by Texas Instruments (TI), are an excellent choice for medical imaging applications. DSPs can be used to provide accurate control of the gantry rotation, the movement of the table (up/down and in/out), tilting of the gantry for angled images, and other functions such as turning the X-ray beam on and off. Another important DSP control functionality is ECG gating used to reduce motion artifacts caused by heart movement. Here, the data acquisition is carefully synchronized with the heartbeat. For interfacing with a PC, gigabit Ethernet transceivers allow for high-speed full-duplex point-to-point data transmissions. The PCI Express™ PHY interfaces the PCI Express Media Access Layer (MAC) to a PCI Express serial link.
The CT Scanner application may have ultra-fast transient requirements for high performance DSP and/or FPGAs, where TI’s high-performance non-isolated power modules are well suited. If high PSRR, fast start-up, and low noise are concerns, low-dropout (LDO) linear regulators are available. TI’s portfolio includes voltage supervisors, DC/DC converters, power modules, and LDOs that allows complete flexibility for the user to configure a power solution that meets the sequencing requirements for the system.