The paper presents three algorithms of an ultrasonic signal compressing. First one is a compression with linear time quantization. Second algorithm of signal compression calculates the rate of signal change and proportionally to it sets the sampling rate. Third algorithm of compression takes some number of random uniformly distributed samples from the original ultrasonic signal. The results of simulations for all three compressing algorithms are presented in the paper. An absolute error and mean square deviations for a wide range of compression ratios are calculated and compared for different compressing algorithms.