188 Lecture 10 
SOUND FIELD OF DIRECTIONAL TRANSMITTER IH SHALLOW WATER 
{Transmitter 2-Qcms. dio. 6=9-30 Frequency 560 kc/s 
Woter Scms. deep.) 
1. Bottom plote glass 
Transmitter In mid-water. 
Fig. 10.27. Picture made 
with a directional trans- 
7, Jottom rubber covered mitter. The bottom is plate 
Transmitter in mid-water glass in the top picture and 
rubber-covered in others. 
Water 2 in. deep. 
3. Bottom rubber covered 
Transmitter near bottom 
4. Bottom rubber covered 
Transmitter near surface 
DIRECTIONAL CHARACTERISTICS 
of BoTi transmitter (2cms. dia.) 
(Transmitter rotating uniform ly) 
(a) 
Point Receiver 
scanning verticolly 
: A : at 1metre range. 
Fig. 10.28. Directional 
characteristics of projec- 
tor. (a) Vertical scan rec- 
ord, (b) Pressure ampli- 
tude record at midwater 
depth, 
(b) 
Point Receiver 
fixed in mid-water. 
Sound pressure 
amplitude 
recorded, 
