Side Scan Sonar Mod 272TD-Users-Manual

8/16/2019 Side Scan Sonar Mod 272TD-Users-Manual

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INSTRUCTION MANUAL

MODEL 272-TD

DUAL-FREQUENCY TOW FISH

APRIL, 2008

Part # 119830 Rev. B

P.O. Box 8504 Little Brook Road

West Wareham, MA 02576

Tel: (508) 291-0057

Fax: (508) 291-2491

Email: [email protected]


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Model 272-TDSide Scan Sonar Tow Fish

This manual is intended to provide the user with an understanding of the operation and care of

the Model 272-TD Dual Frequency Tow Fish with TVG.

EdgeTech has made every effort to document this product accurately and completely. However,

EdgeTech assumes no liability for errors or for any damages that may result from use of this

manual or the equipment it accompanies. EdgeTech reserves the right to upgrade features of this

equipment and to make changes to this manual without notice at any time.

Since clear and concise documentation is inherent for proper operation and understanding of theequipment, we solicit you to contact us with any questions or comments so that we may enhance

this manual.

EdgeTech

P.O. Box 850

4 Little Brook Road


Tel. (508) 291-0057

Fax. (508) 291-2491


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i

TABLE OF CONTENTS

Page

1. Introduction ........................................................................................................1-1

1.1 General .....................................................................................................1-1

1.2 Model 272-TD Tow Fish..........................................................................1-1

1.3 Tow Cables...............................................................................................1-3

1.4 Specifications ...........................................................................................1-5

2. Installation ..........................................................................................................2-1

2.1 General .....................................................................................................2-1

2.2 Tow Fish...................................................................................................2-1

2.3 Tow Cables...............................................................................................2-12.3.1 Tow Cable Selection ....................................................................2-1

2.3.2 Tow Cable Installation and Deployment......................................2-2

3. Operation ............................................................................................................3-1

3.1 General .....................................................................................................3-1

3.2 Pre-deployment Checkout........................................................................3-1

3.3 Tow Fish Deployment ..............................................................................3-1

3.4 Tow Noise ................................................................................................3-3

3.5 Operating Range.......................................................................................3-3

4. Theory of Operation...........................................................................................4-1

4.1 General .....................................................................................................4-1

4.2 Electrical...................................................................................................4-1

4.2.1 Triggering.....................................................................................4-1

4.2.2 Transmitter ...................................................................................4-1

4.2.3 TVG Receiver...............................................................................4-1

5. Maintenance, Repair, and Calibration.............................................................5-1

5.1 Routine Maintenance................................................................................5-1

5.2 Repair ......................................................................................................5-1

5.2.1 Access...........................................................................................5-1

5.2.2 Tow Fish Rearming......................................................................5-2

5.2.3 Damaged Tail Fins .......................................................................5-2


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ii

Page

5.3 Calibration................................................................................................5-2

5.3.1 Tow Fish Beam Depression .........................................................5-2

5.3.2 TVG Ramp (New revision board)................................................5-4

5.3.3 TVG Ramp (Old revision board)..................................................5-7

6. Troubleshooting..................................................................................................6-1

6.1 General .....................................................................................................6-1

6.2 Tow Fish...................................................................................................6-1

6.3 Tow Cables...............................................................................................6-1

6.3.1 Shorted Wire.................................................................................6-1

6.3.2 Open Wire ....................................................................................6-2

6.3.3 Insulation Resistance Breakdown ................................................6-2

7. Parts List, Assembly Drawings, and Schematic Diagrams.............................7-1

7.1 General .....................................................................................................7-1

7.2 Model 272-TD Tow Fish - P/N A27600 ..................................................7-2

7.3 Bridle Replacement Kit - P/N A23385.....................................................7-3

7.4 Accessory Kit - P/N A22467....................................................................7-5

7.5 Tow Fish Electronics Assembly - P/N D27977 .......................................7-6

7.7 50-Meter Tow Cable Assembly - P/N F28348-50 ...................................7-9

Appendix C Model 285 Side Scan Tow Depth Depressor .......................................C-1

C.1 Introduction .............................................................................................C-1C.2 Using the Tow Depth Depressor .............................................................C-1


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iii

LIST OF ILLUSTRATIONS

Figure Page

1-1 Model 272-TD Tow Fish......................................................................................1-2

1-2 Model 272-TD Tow Fish features........................................................................1-31-3 Tow depth versus ship speed for 150- and 600-meter

tow cables with and without Depth Depressor.....................................................1-4

2-1 Model 272-TD Tow Fish termination ..................................................................2-3

3-1 Tow points ............................................................................................................3-2

5-1 Tail fin ..................................................................................................................5-3

5-2 Transducer Assembly...........................................................................................5-4

5-3 Transducer Hookup ..............................................................................................5-9

7-1 Model 272-TD Tow Fish......................................................................................7-4

7-2 Tow Fish Electronics Assembly...........................................................................7-7

7-3 Transmitter/TVG Amp PCB component layout for

Model 272-TD III Tow Fish.................................................................................7-8

7-4 50-meter tow cable assembly .............................................................................7-10

7-5 Wiring diagram...................................................................................................7-11

7-6 Interconnection cable diagram standard cable ...................................................7-12

7-7 Interconnection cable diagram for optional coax type

double armored tow cable ..................................................................................7-13

Appendix C

C-1 Recommended method for attaching Tow Depth Depressor

to tow cable ......................................................................................................... C-3

C-2 Tow depth versus ship speed for 150- and 600-meter tow

cables with and without Depth Depressor........................................................... C-4

C-3 Model 285 Tow Depth Depressor ................................................................C-6,C-7


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v

WARRANTY STATEMENT

All equipment manufactured by EdgeTech is warranted against defective components and

workmanship for repair at their plant in Massachusetts, free of charge, for a period of one year.

Shipping costs are to be borne by the customer. Malfunction due to improper use is not covered

in this warranty and EdgeTech disclaims any liability for consequential damage resulting from

defects in the performance of the equipment. No product is warranted as being fit for a particular

purpose and there is no warranty of merchantability. This warranty applies only if:

(i) the items are used solely under the operating conditions and in themanner recommended in the instruction manual, specifications, or

other literature;(ii) the items have not been misused or abused in any manner or repairs

attempted thereon;

(iii) written notice of the failure within the warranty period is forwarded

to EdgeTech and the directions received for properly identifying

items returned under warranty are followed;

and

(iv) the return notice authorizes EdgeTech to examine and disassemblereturned products to the extent EdgeTech deems necessary to

ascertain the cause for failure.

The warranties expressed herein are exclusive. There are no other warranties, either expressed or

implied, beyond those set forth herein, and EdgeTech does not assume any other obligation or

liability in connection with the sale or use of said products.

Equipment not manufactured by EdgeTech is supported only to the extent of the original

manufacturer's warranties.


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vi

NOTE

The “500 kHz” notation used in this manual is a generic term used

to denote the high-resolution operating frequency. Although this

frequency is not 500 kHz, this reference has been used and accepted

in the industry. The term “100 kHz” is similarly used.


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vii

WARNING NOTICE (Old Revision D28349 Board Assembly)

SCR SENSITIVITY

The EdgeTech Model 272-TD Tow Fish uses very-fast-switching silicon-controlled rectifiers

(SCRs) in the transmitter circuit. The “500 kHz” output circuit requires a high-voltage SCR that

can switch the storage capacitor energy into the transducer in a very short time. This results in a

very high rate of change of current with time (di/dt). Extreme care must be taken when servicing

the Tow Fish electronics so as not to falsely trigger the SCRs and possibly damage them.

When a SCR triggers, it initially conducts through a small portion of its junction. The size of the

initial conducting surface is a function of the SCR’s gate drive current. Therefore, if the gate

drive is not sufficient enough to form an adequate conducting surface at turn-on, the initial

current surge is concentrated in a small area. The junction may then overheat and fail. The gate

drive circuit of the Tow Fish circuitry is designed to provide sufficient current to form anadequate conduction area. However, if the SCR is falsely triggered without sufficient gate drive,

it will either fail or be weakened.

Two main reasons for SCR failures are the result of false triggering due to improper handling

procedures and tow cable problems. An SCR is a very sensitive device and may trigger on very

low gate drives due to radiated or impressed electrical noise on the gate. Radiated noise may be

from electric arcing due to cable problems. Impressed noise is usually from static discharge into

the gate circuit when one inadvertently touches the gate terminal. The former is usually the case

for SCR failures when the electronics has not been removed from the case. The latter generally

occurs when the electronics is being or has been serviced. Note that false triggering may just

weaken the SCR so that it prematurely fails a short time after Tow Fish deployment.

It is very important to protect the gate when servicing the electronics. This is accomplished by

placing a short jumper across the gate and cathode terminals of each SCR before turning the

power on and keeping them in place until service is complete or the individual transmitter is to be

tested.

Some operators have claimed that they have solved their SCR failures by substituting the SCR

with a different type. Although they may have solved the SCR failure problem, what they have

usually done is substitute a much slower unit. The slower unit will reduce the initial junction

surge current but will also reduce the acoustic source level accordingly. This is not

recommended, especially for the “500 kHz” section. EdgeTech is continually looking for alternative and better SCR sources for units with high voltage, current and di/dt rating. Please

contact EdgeTech for the latest recommended units when replacing SCRs.


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1-1

1. INTRODUCTION

1.1 General

The Model 272-TD Dual Frequency Tow Fish is

a hydrodynamically stable towed body which

contains the transducers and electronics

necessary to generate and receive side scan

sonar signals. It is designed for use with the

Model 260 Side Scan Sonar shipboard unit.

Various tow cable systems provide the

mechanical means for towing the fish near the

seafloor and the electrical means for powering

the fish, triggering the transmitters, and sending

the return signals to the shipboard unit.

The Tow Fish incorporates circuits for

transmitting and receiving the standard “100

kHz” side-scan frequency as well as the high-

resolution “500 kHz” frequency. Either one is

selected by a control signal from the Model 260.

The Tow Fish also incorporates a patented time

varied gain (TVG) circuit that compensates for

the known signal losses versus range. This not

only facilitates processing but also reduces thedynamic range requirements of the tow cable,

thereby reducing the susceptibility to electrical

noise pickup.

This manual describes only the Tow Fish and

cables; consult the Model 260 manual for

remaining details of the system

1.2 Model 272-TD Tow Fish

The Model 272-TD Tow Fish is a compactmetal cylinder that can be handled by one

person (Figure 1-1). It is equipped with

stabilizing fins and lead nose weights for

hydrodynamic balance. Identical but separate port and starboard transducers are located just

forward of the electronics section. The

electronics section contains two identical

printed circuit (PC) boards (for the port and

starboard transducers). Each PC board contains

a transducer driver and a TVG circuit for each

operating frequency. The Tow Fish is free-

flooding, except for the cylindrical tail section

containing the electronics. The watertight

electronics section attaches to the transducer

casing by means of an O-ring seal and a singlethrough-bolt for ease of assembly/disassembly.

Cathodic protection is provided internally and

externally. A hinged tow arm is mounted on the

top of the fish, near the center of gravity, and is

fitted with a pressure-proof connector for

electrically attaching the tow cable to the fish.

The Model 272-TD Tow Fish features a nylon

Saf-T-Link shear pin. When cable tension on

the Tow Fish exceeds 180 kg (400 lb), due to

snagging on the seafloor or mooring lines, for example, the pin shears, and the electrical

connector between the cable and Tow Fish

separates. The Tow Fish then “flips” 360,

transferring the tow point to the nose of the Tow

Fish and allowing it to be pulled clear of the

obstruction (Figure 1-2). To restore normal

operation, the Tow Fish is simply remounted in

the towing arm with a new shear pin and the

connector refastened. If only the tail fins snag,

they will fall away and be loosely held by a

nylon cord. The cord will eventually break if thesnag persists (to avoid loss of the Tow Fish).


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1-2

Figure 1-1. Model 272-TD Tow Fish.

1.3 Tow Cables


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1-3

Tow cables of three optional lengths are

available: 600 meters (deep tow), 150-meter

(deep tow), and 50-meter (shallow tow). The

deep-tow cables are double armored, steel-clad

cables; the shallow-tow cable is an abrasion

resistant polyurethane-jacketed cable with aKevlar strength member. The 50-meter cable is

connected directly from the Tow Fish to the

shipboard unit. The deep-tow options require

an additional deck cable.

Typical Tow Fish depths versus speed for several

configurations are given in Figure 1-3. To obtain

greater depths with a given cable, the optional

Model 285 Tow Depth Depressor may be used.

The Model 285 Depth Depressor described in

Appendix A is a small, lightweight unit thatgenerates over 200 kg (450 lb.) of downward

force at 8 knots.

Figure 1-2. Model 272-TD Saf-T-Link


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1-4

Figure 1-3. Tow depth versus ship speed for 150- and 600-meter tow cables with and without

Depth Depressor.


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1-5

1.4 SpecificationsStandard High

Resolution Resolution

Model 272-TD Tow Fish (“100 kHz”) (“500 kHz”)

ELECTRO-ACOUSTIC

Operating Frequencies: 105 kHz ± 10 kHz 390 kHz ± 20 kHz

Pulse Length: 0.1 msec 0.01 msec

Acoustic Output: 228 dB ref 1 micro- 222 dB ref 1

pascal at meter micropascal at

1 meter

Horizontal Beam Width: 1.2° (3 dB points) 0.5°

Vertical Beam Width: 50°, tilted down 20° Same

TVG Range 60 dB to 220 ms 19 dB to 75 ms

MECHANICAL

Maximum Depth: 600 meters (2000 ft)

Weight:

In Water 15 kg (35 lb)

Crated 50 kg (110 lb)

Uncrated 25 kg (55 lb)

Dimensions:

Crated: 1.5 x 0.24 x 0.41 meters

(59 x 9.5 x 16 in.)

Uncrated: 140 cm long x 11.4 cmdia. x 61 cm dia tail

(55 in. x 4.5 in. x 24 in.)

TOW CABLE

MECHANICAL

DEEP TOW

Type: Double armored, steel

Diameter: 0.95 cm (0.375 in.)

Length: 150 meters (500 ft) or 600 meters (2000 ft)

Strength: 5000 kg (11,000 lb)

Minimum sheave diameter: 0.5 meter (20 in.)

Weight in air: 0.35 kg/meter (0.24 lb/ft)

Weight in water: 0.29 kg/meter (0.19 lb/ft)

TOW CABLE (Continued)


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2-1

2. INSTALLATION

2.1 General

The Model 272-TD Tow Fish is supplied with

miscellaneous mechanical spare parts in a

reusable wooden crate. The two cables and

extended electrical spare parts are ordered

separately. Armored cables are shipped on

wooden reels; the 50-meter tow cable is

provided in a reusable transit case.

Before each installation, the system components

should be thoroughly inspected for damage and

all components should be accounted for. Saveall packing materials for reuse.

2.2 Tow Fish

The Tow Fish is relatively lightweight, 25 kg (55

lb), and can be handled by one person. A pin is

provided which locks the tow arm to act as a

convenient carrying handle when the tow arm is

folded all the way back, parallel to the Tow Fish

body. In normal operation, the pin should not be

left dangling. Replace it in the hole on the TowFish body.

Assemble the two tail fin halves together before

inserting them into the grooves on the rear of the

Tow Fish. Pull the steel recovery cable as far to

the rear as possible to allow for easy insertion of

the tail fins. Tighten the two tail fin screws. Tie

one end of the 1/8-inch nylon rope on the tail

fins to the steel recovery cable using two half

hitches. If the Tow Fish hits a snag, the tail finswill be pulled off by the recovery cable and will

hang from it as the tow point is shifted to the

nose of the Tow Fish.

Locate the Tow Fish near the point of

deployment and make the electrical and

mechanical connections to the tow cable.

Electrical connection is made at the top end of

the tow arm.

Shackling the tow cable strength member to theshackle plate on the tow arm (Figure 2-1) makes

mechanical connection. Once the cables are

attached, lash the Tow Fish to the deck. The tail

fins will keep the unit from rolling; however,

care should be taken not to bend the fins, as the

hydrodynamic stability will be affected.

2.3 Tow Cables

2.3.1 Tow Cable Selection

Tow cables perform three main functions: 1)

provide a conduit for the electrical signals, 2) act

as a strength member supporting the Tow Fish,

and 3) provide weight to depress the Tow Fish.

EdgeTech provides several tow cable

NOTE

Use the silicone grease provided on

both mating halves to assist in mating and sealing

Be sure to seize the shackle.


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2-2

configurations to meet various operating

requirements. One type of tow cable is

lightweight and uses Kevlar as the strength

member. Another type has a double-armored jacket. As the tow cable length increases with

increased depth or tow speed, the tow cable

characteristics become the predominant factor in

establishing the Tow Fish depth. With

lightweight cable, there comes a point where the

Tow Fish weight is not sufficient to counteract

the upward forces acting on the cable and

thereby maintain the required tow depth. When

this occurs, armored tow cable must be used.

For shallow water depths, three standard

lightweight cable lengths are available. Twostandard armored cable lengths are available for

deep water.

Both the standard lightweight and armored

cables use individual unpaired conductors.

Because the cable characteristics necessary for

high-frequency operation are neither specified

not controlled in the cable manufacture,

EdgeTech recommends an alternative armored

cable with coax conductors when the cable

length requirements meet or exceed 600 meters.The coax cable signal losses at the optional

“500 kHz” are much less than the standard

cable, they are closely controlled, and are within

1 to 2 dB of that of the 100 kHz signal.

The optional coax cable is also recommended

for shorter lengths (450-600 meters) when

operating at “500 kHz” in soft areas with poor

acoustic returns. A minimum of two coax sets

and three individual conductors are required

with the port and starboard signals dedicated to

individual coax pairs. A standard 3-coax, 3-

individual conductor cable configuration isavailable from several manufacturers. Contact

EdgeTech for specific cable recommendations.

2.3.2 Tow Cable Installation and

Deployment

The 50-meter tow cable is lightweight and

portable. It should be laid out on a deck near

the point of Tow Fish deployment. Before

connecting the cable at both ends, “figure eight”

it to take out all the twists and to allow for easy

pay out. A convenient way to remove twists

from a coiled cable would be to pay out the

unattached Tow Fish end from the stern while

running at 2 to 3 knots. The Kellums grip on

the shipboard end should be securely attached to

the vessel to prevent potential loss of the in-

water package.

Transfer the double armored cables to a winch.

Securely fasten the shipboard end to the drum.

Plans for handling the deep tow cables should be made prior to shipboard installation. The use

of a winch equipped with slip rings will greatly

facilitate system operation. If such a winch is

not available, the deck cable from the recorder

must be disconnected from the main tow cable

before the tow cable can be deployed or reeled

in each time the depth of operation of the Tow

Fish is changed.


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2-3

Figure 2-1. Model 272-TD Tow Fish termination.

Front End of Tow Arm

Back End of Tow Arm


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3-2

Figure 3-1. Tow points.


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3-3

The Tow Fish may be deployed or retrieved by

one person. For deployment, carry the Tow Fish

to the rail and slowly lower it over the side using

the cable. Let out at least enough cable to getthe Tow Fish away from the vessel. Do not

lower the Tow Fish to the full desired towing

depth until the system is turned on. This allows

the actual Tow Fish height above the bottom to

be verified. Use care when bringing the Tow

Fish back on board. Do not allow it to swing, as

it may strike personnel or cause damage.

3.4 Tow Noise

As with any sensor, it is important to keep thesystem noise at a minimum level to make

maximum use of the available signal. A high

noise level can mask important data, particularly

at long range.

The background noise will vary with each

survey depending on the radiated vessel noise,

the tow depth, and the tow speed. Although it is

difficult to predict what noise level to expect,

under most conditions the noise level will allow

clean side scan data out to 200 meters for “100kHz” operation and 75 meters for “500 kHz”

operation, except in shallow water or for soft

sediments.

Once the system is operational, monitor the

noise by turning off the Tow Fish trigger. Then

reduce the noise as much as possible, using the

steps below.

1) Experiment with ship speed to determinethe effect on noise and the maximum

speed for an acceptable noise level.

Some vessels are particularly noisy atcertain speeds; these speeds should be

determined and avoided.

2) Experiment with different towingarrangements, particularly in shallow

water, to determine the quietest

configuration. In general, the farther

away from the vessel, the lower the

noise will be. Avoid locations in or near

the wake.

Finding the true minimum noise level may

require repeating the above steps once a change

has been made. When the quietest configuration

is determined, set the trigger on again. Since the

environment is subject to change, recheck the

noise level from time to time.

3.5 Operating Range

Operating range is a function of the signal-to-

noise ratio. Stronger targets can be detected at agreater range than weaker ones. Range is

reduced considerably if the acoustic or ambient

noise is high. Target resolution also decreases

as range increases. The generally accepted

ranges for standard “100 kHz” operation are:

100, 150, and 200 meters. Preferred operation at

the high-resolution “500 kHz” is from 25 up to

100 meters.

NOTE

When the Tow Fish trigger is off, the TVG is disabled and the

circuit will be at maximum gain. The displayed noise level will be

considerably less on short ranges when the trigger is on.


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Model 272-TDDigital Side Scan Sonar Tow Fish

4-1

4. THEORY OF OPERATION

4.1 General

Unlike a depth sounder, which collects only one

data point for every sonic transmission, side scan

sonar collects a whole line of data. Two identical

transducers collect data to each side, one to port

and one to starboard. Each has a narrow beam in

the horizontal plane and a wide beam in the

vertical plane. The narrow, horizontal

beamwidth concentrates the energy in a swath

perpendicular to the axis of travel. The wide,

vertical beamwidth gives continuous data from

directly beneath the transducer out to themaximum system range. The instantaneous echo

level is a measure of the backscattering strength

or roughness of the seafloor material. As the

transducers are moved forward, subsequent sonic

transmissions generate parallel swaths of data

giving continuous seafloor coverage.

4.2 Electrical

An output of 750 VDC from the shipboard unit

supplies power down the cable for both sets of transmitting and receiving electronics.

4.2.1 Triggering

The trigger pulse width is set by the Model 260

FREQ SELECT switch. It is 125 microseconds

for “100 kHz” operation and 250 microseconds

for “500 kHz.” The incoming signal triggers a

190-microsecond one-shot A1-6 (TP2). At the

completion of the 190-microsecond pulse, flip-

flop A3-1 is set or reset depending on the presence or absence of the trigger signal. The

state of A3-1 sets the operating frequency by

enabling or disabling the appropriate transmitter

and receiver circuitry.

4.2.2 Transmitter

Transmitters for the “100 kHz” and “500 kHz”

are basically the same except for minor

differences in the gating and triggering. The

transmitter is a capacitor discharge type. A

storage capacitor is charged to +750 volts and

when a trigger pulse occurs the stored energy is

dumped through a controlling SCR into the Tow

Fish transducer. The transducer rings and

couples acoustic energy into the water at its own

natural frequency. A matching transformer also

forms a tuned circuit with the storage capacitor at the operating transducer frequency. The

induced transducer voltage is approximately 5

kV peak-to-peak and decays rapidly in about 0.1

msec for “100 kHz” and 0.01 msec for “500

kHz.”

4.2.3 TVG Receiver

The “100 kHz” and “500 kHz” TVG receivers

are similar except that the latter has an additional

gain stage to change the shape of the time-

varying gain. Operation of the “100 kHz”

portion is as follows.

Diodes CR10 and CR11 are essentially a short-

circuit on the high voltage transmit pulse. Once

the pulse diminishes, they then revert to a high

impedance. Acoustic echoes received on the

transducer are converted to electrical signals

which are coupled through T2 to amplifier A8.

A8 and A7 are transconductance amplifiers with

interstage filtering. The gain of each stage is

directly proportional to the control current from

the ramp generator, which sets the TVG rate.

The final output Q13 and Q14 is a fixed gain

amplifier. Transformer T5 matches the output to

a 50-ohm cable impedance.

A 3-msec pulse triggered from the input trigger

initiates the ramp generator. The 3-msec pulse


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4-2

turns Q8 on, discharging C10. At the end of the

pulse, Q8 turns off and C10 is allowed to charge

linearly via the constant current charging circuit

of Q6. Transistors Q9 and Q10 convert the

voltage ramp across C10 to a current ramp which

controls the transconductance amplifiers’ gain

according to a pre-established TVG curve.

CAUTION

DO NOT ADJUST THE TVG POTENTIOMETERS.

They are factory set to give the proper curve.

Misadjustment can severely reduce the quality of the data.

Refer to subsection 5.3.2 for the calibration procedure if the

potentiometers are inadvertently misadjusted.


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5-1

5. MAINTENANCE, REPAIR, and CALIBRATION

5.1 Routine Maintenance

The following routine maintenance procedure

should be performed before and after each

mission.

1) When the Tow Fish is retrieved after use inseawater, rinse it with fresh water to

minimize corrosion.

2) Regularly check the screws that hold thetail fins to the Tow Fish.

3) Apply zinc-rich grease to the Tow Fishfasteners exposed to seawater before

insertion to minimize fastener corrosion.

4) Check the Tow Fish for deep scratches or signs of corrosion. Paint the scratches to

prevent further corrosion.

5) Clean the urethane surface of thetransducers with a mild detergent to ensure

wetting of these surfaces to improve

acoustic coupling into the water.

6) Replace zinc anodes in the top channel asnecessary.

7) Check for fin warpage and repair or replace if necessary.

8) Regularly inspect the cables for signs of

physical damage.

5.2 Repair

5.2.1 Access (refer to Figure 7-1)

Transducers may be inspected, repaired, or

replaced without separating the fore and aft

sections of the Tow Fish housing. Remove the

ten hex-head mounting screws and carefully

remove the transducer and cover-plate assembly

from the Tow Fish body (forward end first).

Color-coded jumper wires connect the rear end

of the transducer to the bulkhead of the

electronics assembly. Refer to Figure 5-3 for the

color code designations needed for re-assembly.

The bridle arm assembly is mechanically pinned

to the fore section of the Tow Fish housing and

electrically connected to the bulkhead of the

electronics assembly.

The electronics assembly can be accessed by

removing the through-bolt (alignment screw and

nut) which connects the fore and aft sections of

the Tow Fish body. This should be done only in

a clean, dry location. Carefully separate the two

sections without putting strain on the electrical

connectors. By carefully pulling on the body of

the large bulkhead connector, the electronics

section can be removed from the aft housing

.

CAUTION

Protect all underwater connectors, O-rings, and O-ring surfaces.

Ensure that they are clean and coated with silicone grease (provided

in Accessory Kit) prior to re-assembly. Ensure that the O-ring is

properly seated in its groove.


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5-2

5.2.2 Tow Fish Rearming

When the Saf-T-Link trips, the Tow Fish must be

rearmed.

A rearming kit containing nylon screws, fuses,and silicone grease is included with each Tow

Fish. Additional kits may be obtained from

EdgeTech.

Bring the Tow Fish on board to remount the Saf-

T-Link, and reconnect the connector. The Saf-T-

Link is held in place by a 10-32 x 1 in. nylon

screw having a breaking strength of 400 lb,

which shears when the Tow Fish snags. This

shifts the tow point to the nose of the Tow Fish

for easier recovery. When reinstalling the Saf-T-Link, unscrew the broken nylon screw from the

towing arm.

When the cable connector on the Tow Fish arm

pulls out during Saf-T-Link recovery from a

snag, it usually causes the 750V fuse in the

shipboard unit to blow. Check and replace the

fuse as part of the Saf-T-Link reinstallation

procedure. Use silicone grease every time the

connector is separated.

5.2.3 Damaged Tail Fins

A bent tail fin may cause the Tow Fish to veer

from its intended tow path and depth; therefore,

an extra set of fins is supplied with each Tow

Fish. Figure 5-1 is a drawing of the fins in case

they have to be remotely manufactured in an

emergency.

5.3 Calibration

5.3.1 Tow Fish Beam Depression

The Tow Fish may be set for a 20° or 10°

depression angle. It should normally be set for a

20° depression angle. When operating close to

the bottom at “500 kHz” at short range (75

meters or less), a 10° depression angle may

improve the range and shadow definition.

Because the Model 260 beam correction is set for

a 20° depression angle, the close-in data may be

improperly highlighted, especially at “100 kHz.”

The beam correction factor in this case may be

altered by the Model 260 internal panel switch

settings. Refer to Section 3 of the Model 260

Manual.

The opening or transducer window in the

transducer assembly is slightly off the horizontal

center line (Figure 5-2). When the transducers

are mounted so that the smaller “B” dimension is

on the bottom, the beam depression angle will be

20° from the horizontal. This is the standard

factory-shipped configuration. For a 10°

depression angle, remove the 10 screws from

each transducer/cover-plate assembly, disconnect

the plugs coming from the electronics, exchange

the starboard and port transducer assemblies, and

reconnect the plugs. The larger “A” dimension is

now on the bottom and the beam depression is

changed to 10°. The 10° and 20° positions are

marked on each transducer, and the positionselected should line up with the index mark cut

into the Tow Fish body.

NOTE:

Insert a new nylon screw from the

threaded side of the screw hole only,

otherwise it will be difficult to remove the

broken section of the screw in the future.


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5-3

Figure 5-1. Tail fin.


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5-4

Figure 5-2. Transducer Assembly (A>B) (exaggerated sketch).

5.3.2 TVG Ramp Calibration Procedure(New Version-D32167 Assembly)

5.3.2.1 Forward

The Tow Fish TVG ramp is factory set.

Because it requires special equipment for

calibration, it should not be tampered with or

adjusted in the field. It is recommended that

the electronics assembly be returned to the

factory for re-calibration if service is required.

The

following procedure may be used by an

experienced technician if time and/or the

situation demands a field adjustment.

This procedure is for the field calibration of the

272-TD III tow-fish receiver section that has

previously been calibrated. Do not be

concerned if some values of the TVG

calibration are not exact as noted below due tothe availability and variability of the test

equipment used. It is more important to have

the same values for both the port and

starboard boards.

5.3.2.2 Equipment Required

• Power Supply, 40VDC

• Digital Voltmeter

• Pulse Generator

• Signal Generator (low-impedanceoutput)

• Step Attenuator

• Oscilloscope

• Counter

• 1:1 50Ω isolation transformer

Note:

There may be times when field

experience dictates that TVG values

be changed to optimize the record to

cover most bottom conditions. It is

advisable to contact the factory for

the latest values used prior to making

any adjustments.


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5-5

5.3.2.3 Reference Drawings:

• 272-TD Manual (P/N 119830)

• Transducer connections, Fig. 5-3

• Board layout drawing, Fig. 7-3

5.3.2.4 Setup & Calibration Notes

This setup uses a low-voltage supply so the

board under test will not have the high 800VDC

present on it.

The test signals in the following procedure are

injected at designated test points. When the

boards are installed in an electronics assembly,

it may be more convenient to apply the testsignals to the transducer single-pin connectors

on the electronics bulkhead. If this is done,

increase the adjusted voltages in the calibration

sections below by around 10% to account for

losses in the input transformer. Refer to the

bulkhead layout drawing.

The 100 kHz and 400 kHz signal-level setup

settings below may be different. Depending on

the signal generator used either 1) store the

setup setting or 2) mark the position of theoutput level control for each frequency. Use

these settings for the respective calibration

procedure.

5.3.2.5 Setup

1. Connect a 50Ω resistor across terminalsE8 and E9.

2. Power Supply

• Connect (–) to terminal E5 (GND).

• Connect (+) to TP9 (TEST).

3. Pulse generator

• Connect hi output to terminal E4(TRIG).

• Connect low output to terminal E5(GND).

4. Signal Generator

• Attach counter to signal generator output.

• Also connect step attenuator to signalgenerator output.

• Attach the isolation transformer to theoutput of the attenuator.

• Terminate the secondary (output) side of

the isolation transformer with 50Ω and

connect a set of shielded test leads.

• Connect the test leads to the 100 kHzinput (low to E3, high to TP10).

• Set frequency to 105 kHz and attenuator to 20dB. Adjust the signal-generator

amplitude for 0.1 V p-p at the attenuator

output.

• Switch in another 20dB and observe that

the amplitude drops to 10 mV p-p. Mark or store the setting. Use this setting for

the 100 kHz calibration procedure

below.

• Connect the test leads to the 400 kHzinput (low to E6, high to TP11).

• Set frequency to 390 kHz and attenuator to 20dB. Adjust the signal-generator

amplitude for 0.1 V p-p at the attenuator

output. Mark or store the setting. Usethis setting for the 400 kHz calibration

procedure below


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5-6

5. Oscilloscope

• External trigger from the pulse generator

• Use ground connection E5 unless

otherwise noted

5.3.2.6 Turn On

1. Set power-supply voltage to 40 VDC

2. Set pulse generator for:

Amplitude +15 volts

Period 450 ms

Width 125 µsec

5.3.2.7 100 kHz Calibration

1. Connect the input-signal test leads to the100 kHz input (low to E3, high to TP10).

2. Connect oscilloscope to E8 (hi) and E9(gnd).

3. Set pulse generator width to 125 µsec, period to 450ms.

4. Set signal generator to 100 kHz setupsetting (105 kHz).

5. Set attenuator for –70 dB.

6. Trigger the TVG and remove the TRIGinput when signal across E8/E9 is at

maximum.

7. Sweep frequency from 80 kHz to 120

kHz and note frequency of maximumamplitude is 110 kHz ±5 kHz.

8. Set signal generator to the peak frequency.

9. Reconnect the Trigger input

10. Set attenuator for –70dB input signal.

11. Adjust MAX control R34 for a 150 mV p-p signal across E8/E9 at maximum

amplitude.

12. Adjust SLOPE control R33 so that the

max signal break point is at 300 ms.

13. Set attenuator for –20 dB input signal.

14. Adjust INIT control R32 for a 60 mV p-p

signal at minimum signal (≈3 ms).

15. Repeat steps 10 through 14 above because the adjustments interact with

each other.

5.3.2.8 400 kHz Calibration

1. Connect the input-signal test leads to the400 kHz input (low to E6, high to TP11).

2. Set pulse generator width to 250 µsec, period to 225ms.

3. Connect oscilloscope to E8 (hi) and E9(gnd).

4. Set signal generator to 400 kHz setupsetting (390 kHz).


6. Trigger the TVG and remove the TRIGinput when signal across E8/E9 is at

maximum.

7. Sweep frequency from 370 kHz to 420kHz and note frequency of maximum

amplitude is 390 kHz ±5 kHz.

8. If the peak frequency is incorrect, proceed as follows.

a. Set signal generator to 380 kHz and adjust L2 for maximum signal across

E8/E9. Note: Use peak with slug near

Note: Peak L2 & L3 with slug near the top of coil. Do not use

peak near the bottom.


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5-7

b. Set signal generator to 400 kHz and adjust L3 for maximum signal across

E8/E9.

c. Repeat above.

9. Repeat Step 7 above.

10. Set signal generator to the peak frequency.

11. Reconnect the Trigger input.


13. Adjust MAX control R22 for 100 mV p-

p signal across E8/E9 at maximumamplitude.

14. Adjust SLOPE control R21 so that themax signal break point is at 120 ms.

15. Set attenuator for –59 dB input signal.

16. Adjust INIT control R20 for a 60 mV p-p

signal at minimum signal (≈3msec).

17. Repeat steps 12 through 16 above

because the adjustments interact witheach other.

5.3.3 TVG Ramp (Old versions Only –

D28349 Assembly)

5.3.3.2 Setup

Proceed as follows: Refer to Figure 5-3

1. Remove the Model 260 from its case.

2. Remove two three-pin connectors P1 and P2 at top of the Model 260 Acquisition

PCB (black handles).

3. Attach a 51Ω resistor across terminals E8and E9 on the board(s) to be calibrated.

4. Connect the tow cable to the Tow Fishelectronics package. Disconnect

transducer cables.

5. Place a clip lead across the two upper

terminals of each of the four SCRs to prevent false triggering.

6. Synchronize oscilloscope on terminal E4;

positive trigger. Monitor across 51Ω

resistor.

7. Put Model 260 to STANDBY and TRIGGER to ON. Be careful of the high

voltage.

5.3.3.3 Calibrate the “100 kHz” section:

1. Set the Model 260 FREQ SELECTswitch to 100 kHz.

2. Set up a low impedance 105 kHz signalsource for both -20 dB and -70 dB signal

referenced to 1 volt peak-to-peak when

applied to the “100 kHz” transducer

terminals (port or starboard) on the

bulkhead for the board to be calibrated.

Connect the high lead to the double letter terminal and low lead to the single letter

terminal (see Figure 5-3).

3. Set RANGE to 300 meters.

4. With the -70 dB signal, adjust the “100kHz” Max. Gain potentiometer R34 for a

150 mV peak-to-peak signal when ramp

is at the maximum level.

5. Adjust “100 kHz” Slope potentiometer R33 for maximum signal level break

point at 300 ms.

6. Adjust “100 kHz” Initial Gain potentiometer R32 for a 60 mV p-p

signal at 3 ms with -20 dB signal input.


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5-8

7. Repeat 11, 12, and 13 as theseadjustments interact.

8. Repeat for other board.

5.3.3.4 Calibrate the “500 kHz” section:

1. Set the Model 260 FREQ SELECTswitch to 500 kHz.

2. Set up a low impedance 390 kHz signalsource for both a -50 dB and a -70 dB

signal referenced to 320 mV peak-to-

peak when applied across CR20.

3. Set RANGE to 150 meters.

4. With the -70 dB signal, adjust the “500kHz” Max. Gain potentiometer R22 for a

100 mV p-p signal when ramp is at the

maximum level.

5. Adjust “500 kHz” Slope potentiometer R21 for maximum signal level break

point at 120 ms.

6. Adjust “500 kHz” Initial Gain

potentiometer R20 for a 60 mV p-psignal at 3 ms with -50 dB signal input.

7. Repeat 19, 20, and 21 several times asthese adjustments interact.

8. Repeat for the other board.

9. Turn power off and remove the 51Ω

resistors and jumpers from the SCRs.

10. Reconnect transducers (see Figure 5-3).

11. Reconnect P1 and P2 to AcquisitionPCB.


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5-9

Figure 5-3. Transducer Hookup.


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6-1

6. TROUBLESHOOTING

WARNING

High voltage (750 VDC) is present on the cable and the electronicsassembly.

6.1 General

Historically, most system problems occur in the

tow cable and/or connectors. Before proceeding,

verify cable continuity.

6.2 Tow Fish

At this point, it is assumed that the systems test

in Section 6 of the Model 260 Manual has been

completed and that the problem has been

narrowed down to one of the Tow Fish

electronic PCBs. A description of the PCB

circuitry operation is given in subsection 4.2 of

this manual.

The transmitter circuitry should be tested with

the transducers connected as damage to the

SCRs may result if an SCR is triggered without

a load. The key critical component of the

transmitter is the SCR.

The TVG circuitry consists of two basic parts,

the ramp generator and the amplifier. When

troubleshooting these circuits, it is best to follow

the procedures in subsection 5.3.2 of this

manual.

6.3 Tow Cables

The presence of shorted or open wire in a tow

cable can be determined by using a multimeter.

Once this condition is isolated to the tow cable,

the open or shorted wire can be located using the

techniques described in the following

subsections.

6.3.1 Shorted Wire

The wire resistance of the double-armored tow

cables is 1 ohm/100 ft or 1 ohm/30 meters.Measurement of the two shorted wires with the

ohmmeter provides the distance to the short. The

following procedure may be used to approximate

the distance to a single short or a point of high

leakage between a conductor pair or from a

conductor to a shield.

1) Disconnect both cable ends.

2) Short the two connector pins (or wires if

unterminated) of the shorted pair at bothends and measure the total resistance

between the ends.

R1+R2=_______________

3) Remove the shorts.

4) Measure the resistance between a shorted pair on one end with an ohmmeter on the

Rx1 scale.

R1+Rs=_______________

5) Measure the resistance from the other end.R2+Rs=________________

6) Add the measurements of 4) and 5) above,subtract the measurement of 2),


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6-2

7) Divide the result by 2. Rs=_________________

8) Subtract the value of 6) from the measured values of 4) and 5).

R1=_________________

R2=_________________

The distance to the short from end #1 is the ratio

of R1/R1+R2 times the total cable length.

Recheck from end #2 which is R2/R1+R2 times

the cable length.

6.3.2 Open Wire

An open wire in a cable is much more difficult to

locate than a short circuit; therefore, a

capacitance bridge is recommended. Measuring

the capacitance from the open wire to the shield

on both ends allows two different capacitance

readings to be recorded. This represents a direct

ratio related to cable length and distance of break

from each end. Before cutting the cable, double-

check the same ratio of capacitance using an

adjacent good wire. The capacitance will vary

from wire to wire, depending on the separation of

the wires.

A break in the cable may also be found or

confirmed by laying out the cable and flexing it

along its entire length until the break is reached.

Attach an ohmmeter using one lead at each end of the open wire. When flexing, the ends of the

broken wire should touch, giving a continuity

reading on the meter.

6.3.3 Insulation Resistance Breakdown

Insulation breakdown is the most difficult fault to

locate. Cable leakage is not necessarily located

near the end terminations. However, the area

near each termination receives the most abuse

and is, therefore, subject to suspicion. Successivecutting of the cable end until the leakage

disappears will prove successful in many cases.

With both ends disconnected, the tow cables

should measure between 100 megohms and

infinity between conductors with a 500-VDC

megohmmeter. When using a multimeter, all

cables wire-to-wire or wire-to-shield should

measure infinity. Any leakage on the multimeter

indicates cable leakage.

CAUTION

Prior to cutting the cable for any of the above reasons, a

careful visual examination should be made for any signs

of physical damage.


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7-1

7. PARTS LISTS and ASSEMBLY DRAWINGS

7.1 General

This section includes the parts lists, and

assembly drawings of the system. Included are

all electronic assemblies and mechanical parts

which are subject to wear, damage, or loss.

Orders for replacement parts should be

addressed as follows:

EdgeTech

P.O. Box 8504 Little Brook Road


Tel. (508) 291-0057

Fax. (508) 291-2491

It is imperative that the following information besupplied with each order:

1. Part Number;

2. Part Description;

3. Reference Designation;

4. Assembly;

5. Model Number; and

6. Serial Number.

The identification plate is located on the main body of the Tow Fish.

When equipment is to be returned to the factory

for repair or evaluation, notify the factory in

advance for a Return Material Authorization

number to be used in all shipments and

correspondence to efficiently track the

equipment.


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7-2

7.2 MODEL 272-TD TOW FISH - P/N A27600 (Figure 7-1)

Qty Part Number Description

1 E17760 Machining, Forward Section

1 E17787 Machining, Tail Section

2 D17708 Fin, Tail

1 D22280 Bridle Assy

1 50369X Screw, Nylon, No. 10-32 x 1 in. lg

1 C17836 Cable, Recovery

1 D17857 Cable, Tow Fish

1 C17720 Plate, Shackle

1 D17726 Bridle

1 B17286 Pin, Retaining, Bridle Arm

1 500763 Screw, Insulator, Nylon

2 500275 Clamp, Cable, Nylon (HOLUB)

2 110892 Ring, Retaining, Stainless Steel (Waldes Truarc)

1 108227 Pin, Quick Release (Hartwell Corp. Lockwell Prod. Co.)

1 B17724 Screw, Alignment1 A17721 Nut, Alignment

2 D28366 Transducer Assy

1 D17719-1 Plate, Transducer Cover, Starboard

1 D17719-2 Plate, Transducer Cover, Port

12 503592 Screw, Flat Hd, Slotted

No. 6-32 x 3/8 in. lg 100° Stainless Steel

20 503681 Screw, Hex Head - Trimmed

No. 6-32 x 3/8 in. lg Stainless Steel


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7-5

7.4 ACCESSORY KIT - P/N A22467 (Included with Tow Fish)


2 506826 Screw, Set, Slotted HD, No. 5-16 x 1/2 in. lg(tail fin mounting)

36 in. 503282 Rope, Nylon, 1/8 in. Dia

1 108227 Pin, Quick Release

5 500275 Clamp, Cable (Modified)

24 503681 Screw, Hex Head - Trimmed, No. 6-32

x 3/8 lg Stainless Steel

(transducer mounting)

2 107956 O-Ring, Buna N, 70 Duro.

2 C22337 Connector Bulkhead, Single Pin

2 A22329 Anode, Zinc, Rectangular

1 B17724 Screw, Alignment

1 A17721 Nut, Alignment

2 D17708 Fin, Tail

2 C22335 Connector, Jumper Assy, Single Pin

1 C22334 Lead, Grounding

1 A22336 Kit, Rearming1 114103 Grease, 8 oz Tube

10 501262 Cable Tie

10 50369X Screw, Shear Pin, Nylon,

No. 10-32 x 1 in. lg

1 135070 Wrench, ¾”


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7-6

7.5 TOW FISH ELECTRONICS ASSEMBLY - P/N D27977

(Figure 7-2)


1 D27933 Plate, Bulkhead

2 D32167 Assy, PC Board

1 C22234 Connector, Eight Pin

9 C22337 Connector, Single Pin (P1)

1 107956 O-Ring, Material

AR 114103 Grease, Silicone


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7-7

Figure 7-2. Tow Fish Electronics Assembly.


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7-8

Figure 7-3. Transmitter/TVG Amp PCB component layout for

Model 272-TD1II Tow Fish.


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7-10

Figure 7-4. 50-meter tow cable assembly.


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7-11

Figure 7-5. Wiring diagram.


50/92


7-12

Figure 7-6. Interconnection cable diagram standard cable.


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7-13

Figure 7-7. Interconnection cable diagram for optional

coax type double armored tow cable


52/92


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54/92

Appendix A

ACI Inter face

A-i

Table of Contents

A.1. Introduction ...............................................................................................................................A-1A.1.1 Specifications........................................................................................................................A-1

A.1.2 Input/Output..........................................................................................................................A-2A.1.2.1 Rear-Panel BNC Connectors ........................................................................................A-2A.1.2.2 Onboard Header Connectors......................................................................................... A-2

A.2. Installation .................................................................................................................................A-2

A.3. Operation ...................................................................................................................................A-2A.3.1 Serial Command/ Status Interface ........................................................................................A-2

A.3.1.1 ACI Commands ............................................................................................................A-2A.3.1.2 Tow fish Status .............................................................................................................A-3

A.3.2 Parallel-Data Output.............................................................................................................A-3A.3.2.1 Port Specifications ........................................................................................................A-3

A.3.2.2 Signal Identification .....................................................................................................A-4A.3.2.3 Data Format ..................................................................................................................A-4A.3.2.4 Operating Modes ..........................................................................................................A-4

A.3.3 DSP Serial-Data Output........................................................................................................A-5A.3.3.1 Port Specifications ........................................................................................................A-5A.3.3.2 Signal Identification .....................................................................................................A-5A.3.3.3 Data Format ..................................................................................................................A-5A.3.3.4 Operating Modes ..........................................................................................................A-6

A.4. Theory of Operation .................................................................................................................A-6A.4.1 General Information..............................................................................................................A-6A.4.2 Circuitry................................................................................................................................A-6

A.4.2.1 Analog Receivers.......................................................................................................... A-6A.4.2.2 CPU...............................................................................................................................A-7A.4.2.3 Timers...........................................................................................................................A-7A.4.2.4 Digital Output ...............................................................................................................A-7

A.5. Jumper Setup and Calibration ................................................................................................A-7A.5.1 Receiver Calibration.............................................................................................................A-7

A.5.2 Jumper Settings.....................................................................................................................A-8A.5.2.1 Parallel Programming Jumpers..................................................................................... A-8A.5.2.2 Serial Programming Jumpers........................................................................................A-8

A.6. Troubleshooting ........................................................................................................................A-9

A.6.1 Programming Jumper Plugs..................................................................................................A-9A.6.2 Tow fish Interface.................................................................................................................A-9A.6.3 Advanced ..............................................................................................................................A-9

A.6.3.1 Setup. ............................................................................................................................A-9A.6.3.2 Commands from Sonar-Processor ..............................................................................A-10A.6.3.3 Status Message from ACI Card .................................................................................. A-10


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Appendix A

ACI Inter face

A-ii

List of Tables and Figures

Table 1 Programming-Jumper Settings .............................................................................................A-11

Figure 1 Board Input-Output Connectors...........................................................................................A-12

Figure 2 Parallel Timing....................................................................................................................A-13

Figure 3 DSP Serial Timing ..............................................................................................................A-13

Figure 4 Analog test points and controls ........................................................................................... A-14

Figure 5 Timing and control ..............................................................................................................A-15

Figure 6 A/D and parallel output .......................................................................................................A-16

Figure 7 High-speed serial output .....................................................................................................A-17


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Appendix A

ACI Inter face

A-1

APPENDIX A

ACI INTERFACE

A.1. Introduction

The Analog Control Interface (ACI) circuit board is an interface between a topside sonar processor and an EdgeTech Model 272-TD ana-log tow fish. This board provides the analog todigital conversion plus individual-channel ana-log-gain control of the tow fish signal. Both par-allel and high-speed serial data are simultane-ously available, however, only one type is gener-ally used depending on the selected processor. A

digital I/O or DSP board is required in the proc-essor to accept this information.

All control functions are selected by on-screenmenu or icon selection at the topside processor.These controls are conveyed to the ACI board via one of the processor’s serial ports.

The ACI board has an ISA form factor. It may beinstalled in the processor or remotely mounted inan external enclosure. When mounted in the processor, the card obtains power from the PC

bus. Other than power, there are no signal con-nections to the bus.

Onboard programming jumpers provide for vari-ous configurations and interface-signal polaritiesto meet the requirements for most sonar proces-sors on the market.

A high voltage supply is required along with the

ACI card to power the tow fish.. It too may bemounted internal or external to the processor. Ananalog test signal is provided for troubleshooting

without the tow fish.

Although the ACI board has been designed tooperate with the EdgeTech Model 272-TD towfish, it will also work with the single-frequencyModel 272-T tow fish. Only 100 kHz data will be available. The ACI board will not work ade-quately with a Model 272 tow fish however.

Note

The electrical interface to the ACI board’s

digital data output is the same as that for

the DCI card that is used with EdgeTech’s

DF-1000 digital tow fish, except that only 2

data channels are available at one time and

the data sampling is 2X. This minimizes

processor design changes when designing

for both boards.

This document provides information on genericinstallation of, and interfacing to, the ACI card.

Refer to other Sections in this manual for spe-cific instructions pertaining to a particular sonar processor.

A.1.1 Specifications

Card Type.............. ISA

Size........................ 4.5 in H x 9.5 in L(11.4 cm H x 24 cm L)

Power..................... +5 VDC via ISA bus or onboard connector

Serial Control Interface:Type ............................RS-232C

Character Baud Rate ... 4800 standard Number of Data Bits ... 8(D7=0) Number of Start Bits ... 1

Number of Stop Bits ... 1Parity...........................NoneHandshaking ............... None required

Digital-Data:

Data-Sample Rate ....... 50 kHz per side scan channelData Resolution...........12 bits per sampleHS Parallel Output ...... 2x16-bit channels in sequenceHS Serial Output......... One 2x16-bit channel in se-

quence, port and starboard Electrical Interface ......Standard CMOS ‘HC’ type

Trigger OutputConnector.................... BNC female

Polarity........................ Positive goingPulse Width.................89 µsecSignal Level ................ 0 to +5 volts (CMOS)Impedance...................1K ohms to +5 volts

100 ohms to 0 volts

Analog OutputsConnector.................... 2 x BNC femaleSignals......................... Port & starboard


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Appendix A

ACI Inter face

A-2

Polarity........................ Detected positive signalSignal Level ................ 0 to +5 volts

Source Impedance....... 100 ohms

A.1.2 Input/Output

Refer to Figure 1 at the end of this appendix for

connector-pin wiring information and Figures 5to 7 for their location. Refer to section A.1.1 for specifications.

A.1.2.1 Rear-Panel BNC Connectors

TRIG OUT ...............Provides a short positive-going TTL level pulse each time the ACI triggersthe tow fish transmitter. With the ACI as master,it is used to synchronize other sonar equipment

PORT / STBD...........Two separate outputs of

the detected analog signals after filtering and amplification just prior to digitization.

A.1.2.2 Onboard Header Connectors

Serial Port J2 ... Ten-pin header that provides bi-directional RS-232 serial communication be-tween the ACI board and a sonar processor. Tow fish commands are input and tow fish status isoutput. Off-board ribbon cable configures to aDB-9F connector.

Parallel Data J4 (ISIS) ........Forty-pin header that outputs parallel side scan data for external processing. Configured for 1:1 compatibilitywith an internal Triton Technology ISIS con-nector.

Parallel Data J5 (SIDE SCAN) .......Forty-pinheader that outputs parallel side scan data for external processing. Off-board ribbon cable con-figures to a DB-37F connector configured for 1:1compatibility with the Triton Technology ISISoff-board connector.

Serial Data J3 (DSP SERIAL) ...........Ten-pinheader that outputs high-speed serial data to anexternal processor. Off-board ribbon cable con-figures to a DB-9F connector.

A.2. Installation

The ACI board may be either installed within thesonar processor’s chassis or external to it. When

installed inside the PC chassis, it is mounted inan unused ISA card slot for power and mechani-cal support. There are no signal connections

made to the PC’s bus. When it is mounted exter-nal to the PC, an external power supply is needed

for the tow fish.Two ribbon cable connections are required be-tween the ACI board and the PC. One is a serialconnection for commands from the PC. Theother is the digital data output to the PC. A digi-tal input board is required in the PC to transfer the digitized side scan data to the PC bus.

There are several system variations. Thereforefor specific wiring and programming-jumper settings refer to the appropriate manual adden-

dum supplied with a particular application. Thedefault settings are for interfacing with theEdgeTech Model 560A sonar processor.

A.3. Operation

A.3.1 Serial Command/ Status Interface

The ACI PCB receives commands from, and sends status information to the sonar processor through a full-duplex serial port. The serial in-terface is through a 10-pin ribbon cable within

the PC. A DB-9F ribbon cable extension isavailable for an external connection. Refer toFigure 1 for signal identification and connector- pin assignment.

A.3.1.1 ACI Commands

Serial signals from the topside processor controloperation of the ACI card. These operationalcommands include setting the tow fish ping rateand its frequency, setting the individual port and starboard amplifier gains, and enabling test sig-

nals.Once a command has been set it retains the lastvalue until the ACI power has been turned off or re-commanded to another setting. Even thoughthe last input is retained, it is advisable to peri-odically re-transmit the command signals to in-sure that the tow fish is operating at the desired setting in case a noise input causes an accidentalswitch to another setting.


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The command message format is

Message,

where is start-of-text (02H) and is end-of-text (03H). The Message content de-

notes the command function. Each function isindividually controlled with its own message.The messages can occur in any order at any rate.

When turned on, the ACI is immediately active.The following are the various command mes-sages accepted by the ACI. The default values atturn on are denoted in bold.

Parameter Command Operation

Range ..........Rxxx.........Sets side scan transmit rate where“xxx” denotes the Range settingin meters. Values of “xxx” are 25,

50, 75, 100, 150, 200, 300, 400,600 and 1000. Range is limited to150 meters maximum at 500 kHz.

Frequency:... F1.............Enable 100 kHz operationF5.............Enable 400 kHz operation

Trigger.........T1.............Turn on tow fish trigger T0.............Turn off tow fish trigger

Test Signal...X1 ............Turn on tow fish test signal

X0 ............Turn off tow fish test signal

Gain (both channels).....G0 to G4 ..Gain number. Simultaneous sets

the baseline gain on both port &

starboard channels in 6 dB steps.Both channels are set to the same

gain. G2 is default setting.

Gain (individual)......P+, S+

P-, S- ........Each command input incremen-tally increases or decreases gain

of the respective port or starboard channel in 1.5 dB steps to a limit

of ±12 dB from the G2 default

setting.

Reset............Z...............Software reset of the ACI proces-sor. Resets the ACI board withouthaving to power down the sonar

processor.

A.3.1.2 Tow fish Status

A serial message from the ACI card providesinformation of the its operating mode. This mes-sage may be used by the sonar processor to con-firm that the tow fish is operating at the com-manded settings. This message occurs at a 1 Hz

rate. The Message content consists of six datafields separated by commas as follows. Note:Spaces are shown below only for clarity. There

are no spaces in the message.

$ETACI, Range, Frequency, Port Gain, Starboard Gain,

Trigger, Test Signal

A typical status message is

$ETACI, R100.0, F1, P3.0, S-1.5, T1, X0 ,

where,Range ................................... 100 metersFrequency............................. 100 kHzPort Gain .............................. 3.0 dBStarboard Gain ..................... -1.5 dBTrigger .................................OnTest Signal ...........................Off

The port and starboard gain values are relative tothe default start-up value (G2) used for calibra-tion.

A.3.2 Parallel-Data Output

The parallel output provides two channels of sidescan data; either port and starboard 100 kHz, or port and starboard ‘500 kHz.’ For every sonar sample, port and starboard data are output in se-quence. Either the byte location from start-of-

transmission or the built-in ID bits may be used to identify the particular sample.

Data transfer may be setup for either DMA con-trol from the external host or continuous transfer.An internal FIFO allows for asynchronous datatransfer between the ACI and host.

A.3.2.1 Port Specifications

No. of Channels...... 2Port & Starboard,

100 kHz or ‘500 kHz’ No. of Data Bits...... 16 per sample per channelData Resolution ......12 bitsData Sample Rate... 50 kHz per channelData Throughput .... 100 kHzOutput FIFO...........512 bytesOutput Drive........... 10 LS TTLInput .......................CMOS (74HC)


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Connector................2x20-pin header internalDB-37F external

A.3.2.2 Signal Identification

Not every signal associated with the parallel port

is used by all sonar processors. Refer to Figuresfor input/output pin numbers and for timing in-formation. On-board jumpers select the control-signal polarity. The default settings are shown.

D15-D0......Data output signals.

D15-D4 ..........Side scan data, MSB-LSBD3 ..................Not used. Always a zero.D2, D1............Channel ID

00 Port 100 kHz01 Stbd 100 kHz10 Port 500 kHz11 Stbd 500 kHz

D0 ..................Toggles each sonar ping

IRQ ..... User-selectable positive or negative-

going output pulse approximately 35 µsecwide that indicates the start of a new side

scan line. (Default is IRQ+)

DRQ ..... User selectable positive or negativegoing output signal that when asserted,indicates that data is available for transfer

to the external host. As long as DRQ is as-serted, data is available in the FIFO for

transfer. (Default is DRQ+)

RD….. .. User selectable positive or negative

going data clock output 2.6 µsec wideused in the continuous data transfer mode.Output data is valid on the trailing edge of RD or at a minimum of 120 nsec after the

leading edge. (Default is RD-)

DACK... User selectable positive or negative

going input signal from the host thatclocks out the parallel data in the DMAtransfer mode. Data read is initiated on theleading edge and is valid on the trailingedge. The host can continually applyDACK pulses for continuous data transfer as long as DRQ remains asserted. TheDACK pulse width must be 20 nsecminimum. DACK is disabled for the con-

tinuous-mode data transfer. (Default is

DACK-)

A.3.2.3 Data Format

The 16-bit data word consists of 12-bit of digit-

ized data and four housekeeping bits. Of thelater, two bits identify the side scan channel, one bit identifies alternate side scan lines, and one isnot used. For each data sample, the output se-quences through the two channels with port al-ways the first output.

At the start of each sonar line, Bit D0 toggles

between high and low and remains in the samestate for the duration of the line. This bit can beused to indicate the start of a line for both real-time or post processing. It may be also be used to

group samples within a line.

A.3.2.4 Operating Modes

An onboard jumper establishes whether the output data transfer is continuous or controlled by ahandshake signal from the host processor.

A.3.2.4.1 DMA Handshake Mode

At the start of a new line, IRQ is asserted. Thehost processor, using IRQ as an interrupt, ini-

tializes for DMA transfer. When data is avail-able, DRQ is asserted notifying the host that datatransfer can start. The data byte is output whenthe host asserts DACK and is stable for read-in by the host at the trailing edge. If that is the onlydata byte available, DRQ will reset, notifying thehost that there is no more data available. If onthe other hand data is still available in the FIFO,DRQ will remain asserted signifying to the hostthat it can continue data transfer until the buffer empties.

A.3.2.4.2 Continuous Mode (default)

Data is continuously loaded and transferred tothe output buffer as it is sampled. The FIFO isnot utilized. Neither is the DACK handshakesignal from the host. IRQ is asserted at the startof a new line and DRQ is asserted when data isavailable. RD is used by the host to synchronizedata readout from each channel. The host must


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maintain the word transfer rate for the two chan-nels in order to keep up with data sampling.

A.3.3 DSP Serial-Data Output

The high-speed serial port is designed to inter-

face to a DSP processor. Data is transferred tothe host through a single serial channel. For eachsonar sample, a 32-bit data string is output, 16 bits of port followed by 16 bits of starboard,MSB to LSB. Output data rate is set by either thehost processor or an onboard clock. Programma- ble jumpers set the source and rate.

When interfacing to a DSP, operate the DSP inits ‘variable’ mode because data is transferred in bursts, not continuous. Set the I/O board for

continuous mode without host control as pre-sented below. The same applies to third-party boards that use the TMS-320 series such asSonitech’s Spirit 30 family.

A.3.3.1 Port Specifications

No. of Serial Ports ....1P&S, 100 kHz or P&S, 500 kHz

No. of Data Bits........16 per sample per channelData Resolution........12 bits

Data Transfer Rate ...SelectableExternal ....................10 MHz maximum.

Internal .....................2, 4, 8 & 16 MHzData Sample Rate.....50 kHz per channelData Throughput ......100 kHzOutput Drive.............10 LS TTLInput .........................CMOS (74HC)Connector .................2x5-pin header internal,

DB-9F external

A.3.3.2 Signal Identification

Refer to Figure 1 for input/output pin numbersand Figure 3. for timing information.

NEW LINE.... Positive going output pulse ap-

proximately 120 µsec wide that indicatesthe start of a new side scan line.

SYNC OUT.....Positive or negative going output pulse (user selectable), one XCLK cy-cle wide that notifies the external proces-

sor that the first bit of the 32-bit data block will be available on the next fallingedge of XCLK.

SER OUT.....Sequential output data string of 16 bits of port data followed by 16 bits of

starboard data, MSB to LSB, for each data point. Data is clocked out at the rate of XCLK and is stable for readout on thefalling edge.

XCLK..... Data transfer clock. A shared input tothe ACI when data transfer rate is set bythe host processor. An output to the host processor when data transfer is set by theACI. Onboard jumpers set clock source.

SEND DATA....Control input signal that noti-

fies the ACI that the external processor isready to accept the next 2x16-bit datastring when in the handshake mode. En-ables data transfer when in the continuousdata-transfer mode.

A.3.3.3 Data Format

Data is transferred through a single serial chan-nel. For each data sample, 16 bits of port data areoutput followed by 16 bits of starboard data.

Each 16-bit data word consists of 12-bit digitized data, two bits that identify the side scan channel,one bit that identifies a side scan line, and onenot used. The output order of the 32-bit word isillustrated below.

B1....................Always a zeroB2-B13............ Port side scan, MSB-LSBB14-B15..........Channel ID

00.......Port 100 kHz10....... Port 500 kHz

B16.................. Toggles for each line

B17.................. Always a zeroB18-B29.......... Stbd side scan, MSB-LSBB30-B31..........Channel ID

01....... Stbd 100 kHz11....... Stbd 500 kHz

B32.................. Toggles e

Side Scan Sonar Mod 272TD-Users-Manual

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