Construction and testing of low-noise hydrophones

Several hydrophones have been constructe d exploiting the advantages of the MiniCan design. One of them is unamplifie d and two are amplified. Comparison in sensitivity, self-noise, size a nd price with known and reli able commercial hydrophones yield the following results. The unamplified MiniCan has sensitivity 22 dB re 1 V/μPa higher than a Brüel & Kjær type 8103 up to 20 KHz and the amplified MiniCans are compared to their similar and relatively expensive commercial hydrophones. The self- noise level of the amplified MiniCans is significantly lower than those of the B&K 8106 and Reson TC4032. The size of these preamplif ied MiniCan units is at least 18 times smaller in volume than the largest of the aforementioned. Moreover, the cost of the piezoceramic material and electronics comp onents is around $30 USD, compared to purchase prices of $3095 and $2500 US D for the B&K 8106 and Reson TC4032 respectively. The is shows a relatively cheap hydrophone that is more sensitive than a typical hydrophone and better self-noise than the least noisy commercial hydrophone in the market while being smaller and much cheaper. http://archive.org/details/constructionndte109456237 Lieutenant, Mexican Navy Approved for public release; distribution is unlimited.