In a diagnostic ultrasound sector scanner, the sampling space is in the polar coordinates while the display space is in the cartesian coordinates. Therefore a coordinate transformation logic is necessary to utilize raster scanned display device. Also, an interpolation process is required to fill the 'missed pixel' in the far field, which is known as the 'Moire artifact'.
In this paper, a new data space is proposed in order to identify the sampling space with the display space, which is an ideal coordinate transformation. In this 'quasi-polar space', the lateral direction is in the polar coordinate and the vertical direction is in the cartesian coordinate. The sampling process is done by 'CSRS (Concentric Square Raster Sampling)' which is proposed by OPPENHEIM and the display process is accomplished by a variable delay/speed technique.
The implementation requires a high speed frequency synthesizer and its interface to the DSC, which is solved by a digital table look-up method. Then, interpolation can be done just before display by a low-pass filter which is a ideal interpolator.
The overall performance is superior to the conventional sector scanning systems with complexity greatly reduced.
