We have used a pseudorandom (PN) coded signal to investigate the improvement of the signal to noise ratio (SNR) in B-type echography. With N≈10³ bits of code the experimental value of SNR is about 55 dB for PN sequence, close to the theoretical value of 20 log N ≈60 dB. In order to assess the respective advantages of the classical echo images and those obtained with coded signal, we present some B-type images obtained from objects of elementary geometry with application to non destructive testing and medical imaging. We show that the SNR improvement obtained with PN sequence allows the observation of details which would remain invisible with classical echographic techniques