A three axis acclerometer is required to measure the orientation of the ultrasound probe and compensate the force applied onto the patient.
Analogue is in favored upon digital as the output is simply a voltage proportional to the gravity change and can be load into the microcontroller through one of the Analogue input ports of DB28020. Whereas if a digital accelerometer is used, an additional timer component is required to count the cycles in order to convert number of digital high square waves into acceleration.
A as large as possible dynamic range and sensitivity would be advantageous whereas a bandwidth of a couple of hundreds HZ could be sufficient.
Through the searching process, I have found a accelerometer from Analog Devices that supports sampling, since it is free, I have made a application, it will be shipped from Austria on 4th April. It is able to withstand 10000g of shock, with a measurement range of 200g and a typical sensitivity of 6.5mV/g at 3V. The active range of input voltage varies from 1.8V to 3.6V. There is an evaluation board priced at £23.27 based on this component. According to the technical information provided by Analog Devices on this product, I have capacitors that would give me a bandwidth of 500Hz when connected with the sample.
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