Several DSP methods have been synthetically analyzed
and compared with respect to the expected errors for an
ultrasonic range measurement arrangement. These included
L1, L2 norms and correlation. Conventional
threshold-detecting techniques give errors in the range of
several millimeters to centimeters using the low-bandwidth
transducers currently available for operation in air.
In contrast, DSP methods achieve orders of magnitude
better accuracies. Correlation is the best method with low
S/N ratio, the sampling rate being the limiting factor.
Furthermore, L2 norm provides better results with moderate
and low noise levels, although it requires high sampling
frequency, high digitizing resolution, and higher
computing time to achieve its full performance. For moderate
accuracy requirements, L1 needs both low cost
hardware and lower computing time using conventional
architectures. Also, results show that 6-8 b of resolution
are enough for most applications. For higher throughput
Digital Signal Processing
Techniques for
High Accuracy
Ultrasonic
Range Measurements