| 摘要 |
PURPOSE:To automatically, rapidily and accurately measure S/N, by discriminating the target echo sound from the background noise by the timing attained the maximum increment of variation quantity of reception signal of sonar etc. and carrying out the logarithm transformation, subtraction processing of reception signal. CONSTITUTION:An A/D converter 4 is controlled by a timing controlling circuit 5 so as to carry out the conversion between tC-DELTAt-tC+DELTAt in accordance with a cursor set point tC and a cursor moving value DELTAt before the target echo sound which is set by the sonar operator. Then, a maximum point tp of increment of variation quantity of effective value of A/D converted sonar reception signal is discriminated by a target echo sound.background noise discrimination circuit 6 and an averaging circuit 7 is controlled. Hereby, discriminated background noise average signal and target echo sound signal, are processed by a logarithm transformation circuit 8 and subtraction circuit 9 and then, S/N is automatically measured rapidly and accurately, not using visual observation such as oscilloscope. |
