Towfish; Splashproof Transceiver And Processing Unit; (Sp-Iii Tpu) - Klein 4900 Series Operation And Maintenance Manual

1-2
CHAPTER 1 Overview
1.2.1
The towfish, which is shown in Figure 1-1, consists of a negatively buoyant
stainless steel housing with attached port and starboard sonar transducers, a nose
cone and a tail cone with stabilizing fins. The housing contains the sonar
electronics, a downlink demultiplexer for control signals and an uplink multiplexer
for sonar and sensor data. Internal sensors include a compass and motion sensor
which provide heading, pitch and roll; a pressure transducer which provides water
pressure for calculating depth; and a temperature sensor which provides water
temperature. The downlink control signals and the uplink sonar and sensor data are
multiplexed onto a single conductor coaxial tow cable. An electro-mechanical
termination is provided on the towfish end of the tow cable, where a shackle
provides a strong, reliable mechanical termination to the towfish tow bracket, and
an underwater connector connects to a jumper cable on the towfish. Four carrying
handles, two forward and two aft, are included for lifting and transporting the
towfish, and a safety cable tab is provided for connecting the safety cable to the
tow cable.
1.2.2
The Splashproof Transceiver and Processing Unit (SP-III TPU) contains the
electronics for processing the sonar data and powering and communicating with
the towfish. The SP-III TPU is shown in Figure 1-2. The SP-III TPU is built into a
rugged, lightweight splashproof case and contains the electronics for powering the
towfish, downlink multiplexing the control signals to the towfish, uplink
demultiplexing the sonar and sensor data from the towfish, and communicating
with the laptop computer. The SP-III TPU also provides a navigation input. All of
the connectors, indicators and switches are splashproof and are located on a panel
on the side of the unit. The SP-III TPU is powered from either an AC or DC power
source.
Series 4900 Sonar System Operations and Maintenance Manual

Towfish

Splashproof Transceiver and Processing Unit

(SP-III TPU)

CAUTION Do not submerge the SP-III TPU in water, as it is not designed
for continuous immersion.
P/N 11210091, Rev. 02