Table 5.
Summary of the harmonic components measured during Isp measurements at the focal peak using the Onda hydrophone. The components at the 2nd, 3rd and 4th harmonics are included and expressed as a percentage of the prms value. The effect of the attenuator and increase in drive power at the ‘high’ setting, compared to the ‘moderate’ setting, is expressed as a percentage change in the measured harmonic components and the prms values
| Focal peak pressure harmonic/rms | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Drive setting | Harmonic | Transducer | |||||||
| 1 | 2 | 3 | 4a | 4b | 5 | 6 | 7 | ||
| low | 2nd | 13.4% | 8.9% | 3.3% | 10.8% | 9.4% | 3.4% | 10.8% | 10.9% |
| 3rd | 2.1% | 0.7% | 0.3% | 0.8% | 0.9% | 0.3% | 1.0% | 1.1% | |
| 4th | 0.3% | 0.1% | 0.2% | 0.1% | 0.1% | 0.1% | 0.1% | 0.1% | |
| moderate | 2nd | 35.1% | 26.1% | 10.0% | 31.9% | 24.5% | 10.2% | 32.6% | 30.3% |
| 3rd | 17.3% | 8.6% | 1.2% | 9.2% | 8.5% | 1.3% | 13.4% | 12.1% | |
| 4th | 8.3% | 2.8% | 0.2% | 3.2% | 2.8% | 0.2% | 5.2% | 4.6% | |
| high | 2nd | 36.4% | 28.3% | 15.3% | 18.1%* | 28.6% | 12.6% | 34.0% | 26.9% |
| 3rd | 18.3% | 10.1% | 3.5% | 2.6%* | 10.4% | 2.2% | 14.8% | 10.4% | |
| 4th | 8.9% | 3.5% | 0.9% | 0.5%* | 3.3% | 0.4% | 6.0% | 3.6% | |
| Pressure high/moderate %change | |||||||||
| 2nd | +3.8% | +8.3% | +53.7% | -43.2%* | +16.7% | +23.8% | +4.3% | -11.3% | |
| 3rd | +5.6% | +17.8% | +190.0% | -72.1%* | +22.6% | +67.4% | +10.5% | -14.3% | |
| 4th | +6.9% | +26.8% | +506.7% | -84.9%* | +21.0% | +137.5% | +16.1% | -21.8% | |
| Prms | +13.1% | +3.6% | -3.9% | -47.5%* | -10.0% | -0.9% | +8.4% | +9.1% | |
*
Required increase in drive level at ‘high’ power setting not possible due to transducer power limit.