Table of Contents
Advertisement
Microphone Amplifier Type 2603 and the Condenser Microphone Type 4133.
With this combination a frequency range of 200-40ooo Hz is covered.
When substituting the BFO Type 1013 with for instance the Type 1022 a
20~20ooo
Hz frequency range wil be obtained. The measurements were
carried out in an anechoic chamber to ensure that no reflection would in-
fluence the measured results.
Fig. 5.11. Directional characteristics of loudspeaker measured at the
frequencies 1ooo Hz, 8ooo Hz and 16ooo Hz.
The dotted curve is obtained by utilizing the pen lifting arrangement
in
combination with the Two-Channel Selector.
Recording of the Frequency Response of Sound Projectors.
In Fig. 5.12 is shown the measuring set-up for recording the frequency
response of an underwater sound projector. In order to avoid undesired
reflections of the sound waves the projector and the hydrophone should be
placed in an approximately free field
(the
sea, a lake or an anechoic tank).
The projector is fed from the BFO of Type 3306 and the driving voltage is
kept constant by connecting the Oscillator output to the terminals marked
COMPRESSOR INPUT. The sound pressure level at some distance away from
the projector is measured with a standard hydrophone which must have a
flat frequency response in the required range. The electrical output signal
from the hydrophone is then fed to the Level Recorder via a suitable
a5
Advertisement
Table of Contents
