Ultrasonic Underwater Depth Measurement

A0069 Shahram Etemadi Borujeni Department of Computer Engineering, Faculty of Engineering, University of Isfahan

It is required a precise, linear indication of the depth of water in a

specific part of the sea. This demands a continuous level measurement.

There are a wide variety of ways to produce a signal that tracks the

depth of water in a specific part of the sea. Ultrasonic detectors

find the distance betwwen seabed to the surface of the water. To

measure level, depth, with an ultrasonic range detector, module, we

mount the module at the bottom of the sea, seabed, looking up at to

the surface. We must measure the time between the transmit pulse and

the echo received pulses. Since the ultrasonic signal is traveling at

the speed of sound, the time between transmission and echo received is

a measure of the distance to the surface ,water depth.

A micro-controller sends a pulse to the ultrasonic module. The module

is transmitting an ultrasonic wave for a short period of time and wait

for receiving its echo. As soon as echo received to ultrasonic module,

is sent a pulse to micro-controller, which measures the time between

two pulses.

There are two modes of operation, program mode and run mode. When the

unit is powered, it is programmed to start up in the run mode, to

detect the distance from the transducer face to a target, depth, in

meter. The unit can be placed into program mode at any time by

pressing the menu key to alter a value of parameters in order to

better suit the application or user preferences. Unit of measurement,

type of measurement, set point of alarms and factory setting are some

of its parameters. The working time of transition and receiver part

of the module is specifies by micro-controller normally for each "0.5 "

second "10 " ultrasonic pulse is transmitted a remaining part of the

period. The measuring error is approximately "1.25 % ". Such an

error value is acceptable with reception to wavelength of ultrasonic

waves. For so many application that the precision of Cm is sufficient

ultrasonic level measurement is suitable. The system protected from

virtual echoed by using threshold and counting number of echo pulses.