M. P. Foach 119 
Atténuateur de réglage 
Tension référence 
eTR TR 
Voltmetre (GM 6015) 
(GM 6015) 
mA thermocouple Y 
Hartman et Braun 
1) Générateur Muirhead 
2) Ampli de puissance 20 w (D.S.M./B) 
3) Ampli D.S.M./B 
4) Filtre d'octave 34 70 kHz (D.S.M./B) 
q Hydro Emission [] Hydro Réception 
Fig. 6.17. Instrumentation on the barge of Le Brusc. 
6.3.3, Electrical Installation 
Power of 9.5 kv-a is provided by electric supply from the shore through a 
submarine cable. 
6.3.4, Water Depth 
One limitation on measurements is imposed by the water depth under each 
well area available for the realization of free-field conditions. By way of il- 
lustration, Fig. 6.18 shows some field curves measured at various frequencies 
between standard projectors P30P. 
It can be said that the test andcalibration barge of Le Brusc provides means 
for precision measurements in a frequency range down to 6 kcps. 
6.4. TEST-AND-CALIBRATIGN BARGE OF THE LAKE OF CASTILLON 
6.4.1. Introduction: History 
The enlarging of the field of underwater acoustics research by measurements 
in the low and very low frequency range emphasized, several years ago, the 
necessity of an acoustic range suitable for these frequencies. 
As it had not been possible to discover a point along the Mediterranean 
coast sheltered enough to make measurements at great depths, the necessity of 
finding a deep lake became evident. All the natural and artificial lakes in the 
near and far countryside of Toulon were surveyed during the years of 1956 and 
1957, when at last the choice fell on the artificial lake of Castillon. 
The ambient underwater noise level in this lake is very low, corresponding 
to sea state zero (-16 db), and a water depth varying from 50 to 80 m can be ob- 
tained for a test facility afloat in the middle of the lake. 
The project was studied and carried out by the Repair Group of the Naval 
Shipyard (DCAN) of Toulon, with the help of the Naval Artillery Section and the 
General Workshop of the Yard. 
The steel frame and the floats were sent by rail from Toulon to St. André- 
les-Alpes, and from there hauled by truck to the improvised assembly yard on 
the bank of the lake on May 12, 1959. The assembly work and the launching 
preparations were carried out with all desirable speed by the Société Industrielle 
Toulonnaise, and the barge, shown in Fig, 6.19, was launched on August 13, 1959. 
