Compression and Analysis of Ultrasonic Doppler Blood Flow Meter Data by the Discrete Chebyshev Transform

The new scheme to ultrasonic Doppler blood flowmeter (DBF) signals compression through the Discrete Chebyshev Transform (DChT) is developed. The first kind Chebyshev polynomials of up to the 256th order are used for high quality approximation. These polynomials have interesting properties that make them very attractive for the tasks of the optimal polynomials interpolation. The compression mechanism consists of the following steps: segmentation, decomposition into the basis of Chebychev polynomials, and selection of only those that are less than a certain threshold. Modifying the threshold, we can adjust the compression ratio. There are no restrictions on the location of the characteristic waves inside a DBF block. Thus, segmentation within multiple cardiocycles can be performed arbitrarily, but it is only necessary to determine the length of the block. The performance of the proposed method is evaluated with the parameters of compression ratio (CR) and Percent Root square Difference (PRD). The method is very fast that makes it useful in the data communication in telemedicine. The results obtained are optimistic in terms of DBF signal reconstruction error at given compression rates. Additionally, with our processing, the redundant data stream could be reduced to the most significant parameters that could efficiently contribute to medical decision making.