In ultrasonic diagnostic equipment, I/Q signals are usually used for the co
nstruction of B-mode images. displays in the M-mode, and the acquisition of
Doppler information. On the other hand, the number of ultrasonic diagnosti
c equipment in which the digital technique is applied has continuously incr
eased. Accordingly, it is important to understand how I/Q signals are digit
ized and compressed. In this study, the compression of I/Q signals by wavel
et transform is attempted. First, the results are compared with those of a
typical compression method by discrete cosine transform (DCT). The proposed
method achieved a higher compression ratio than DCT under the same quality
of the restored signal. Then, several types of mother wavelets (MWs) are t
ested. The MW can control the efficiency of compression. The result suggest
s that the most appropriate MW for I/Q signals compression exists.