Measurement of the insertion loss

The insertion loss characterize the sensitivity of a transducer, and is given by :

In order to measure the insertion loss of a transducer, an ultrasonic burst is emitted by the transducer. The same transducer receives an echo issued from a plane perpendicular target, which acoustic impedance differs very much from the liquid used as a transmitting media. The voltage ratio between the echo and the emitted burst, expressed in logarithm, is called Insertion Loss (IL).

Signal Processing's transducers have an IL between 6 and 20 dB, depending on the type of transducer.

To measure the Insertion Loss of a transducer, you need the following equipment:

Burst generator setup

Connect the transducer, the burst generator and the oscilloscope as shown in the figure above.

Caution

To prevent any damage to the burst generator, we recommend to check the specifications of the instrument in order to verify that it can support the connection of a very low impedance (<50 ohm) during a long time.

Measuring procedure

  1. Be sure to have a good coupling between the transducer and the liquid(no air bubbles).
  2. Be sure that the transducer is perpendicular to the target (max echo voltage).
  3. Measure the voltage of the emitted burst.
  4. Measure the voltage of the echo.
  5. Compute the Insertion Loss.

Important notices

F [MHz] D [mm] Tk[mm]
0.5 60 20
1 40 10
2 40 10
4 30 10
8 30 5
10 30 5
Sound velocity of 1500 m/s (water).

Signal Processing SA   6 ch. du Cret Rouge   1073 Savigny   Switzerland
Tel:+41 21 683.17.17       FAX:+41 21 683.17.18       email: contact@signal-processing.com