aseline D 
1g situation. 
nce plane 
is not recor- 
Xn- and Y- 
ording of 
ade at Han- 
5 and the 
iilt, which 
  
nt water 
baseline can 
ines at a 
1s. which 
hich con- 
lemetry sy- 
tow cable 
e produced 
| two trans- 
jy both and 
this proce- 
etric sonar 
channels. 
Fig.8. Interferometric Side-Scan-Sonar Fish (open) 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
SONAR FISH EG & G MODEL 272 
MODIFIED TO AN INTERFEROMETRIC EQUIPMENT 
RATE TRANSDUCER (3-AXIS) 
(HUMPHREY RTO2) 
Trigger | I | 
ee Pitch Roll Yaw 
SONAR TRANSMITTER Pont i A i ; 
or 
SONAR RECEIVER VOLTAGE / FREQUENCY CONVERTER 
(EG&G) Sonar Signals Rate Sicnals 
starvors | T ¢ + 
2 TELEMETRY TRANSMITTER 
FREQUENCY SEPARATING FILTER 27.045 MHz 27.145 MHz 27.255 MHz 
1 2 
  
  
  
  
  
TOW CABLE ( EG & G ) 
  
Fig.7: Electronic equipments in the ISSS-fish 
3.2 A Special System for Data Preprocessing and Recording 
Signal processing and recording is still controlled by a standard recorder belonging to 
the EG«G system. Between fish and recorder a special data processing equipment is in- 
stalled. It is the housing of the explained electronic signal mixing, whjch includes a 
changeable low-pass filter and a frequency control unit. Furthermore this system con- 
tains the electronic parts for seperation of rate-transducers signals and the two image 
data strings. All information is stored on PCM-controlled videotape. organized as fol- 
lows: One channel on tape starts with the rate signals followed by the image data of an 
interferometric image line, while the other channel gets the standard sonar signal with 
the trigger pulse at the beginning. Trigger and rate signals are recorded with negativ 
sign and are later used as indicators for line start at analog/digital conversion. The elec- 
tronic parts are installed in a transportable cabinet, which enables employment on diffe- 
rent vessels.