Simrad PI TWIN SPREAD - QUICK REFERENCE GUIDE REV B, PI Twin Spread Quick Reference Manual

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(CD11207A)

Quick reference guide

PI Twin Spread sensor

Purpose

The PI Twin Spread is used with two

Remote sensors to measure the physical

distance between the trawl doors during

twin trawl operations.

(A) = The PI Twin Spread sensor

communicates with the PI system

on the vessel.

(B) = The PI Twin Spread sensor

is mounted on the port trawl

door.

(C) = One PI Remote sensor is

mounted on the center clump.

(D) = One PI Remote sensor is

mounted on the starboard trawl

door.

Daily operation

Once installed and put to use, the

Twin Spread sensor will automatically

be switched on once the waterswitch is

activated. After an initial startup, the sensor

starts interrogating the Remote sensors

to measure the two distances. The results

are transmitted to the vessel. When the

sensors are not in use, check that the sensor

lamps (D) do not flash from time to time,

as this indicates that the sensor is on and is

discharging its batteries. In this case, wash

the sensor in fresh water to remove salt and

dirt.

If you operate with Fast update rate, the

sensors must be charged approximately

every 24 hours. Used with Normal or

Slow update rates, the operational life is

approximately 48 or 70 hours respectively.

For the Remote sensors, the batteries will

last approximately 50, 100 and 150 hours

respectively. The optimal sensor charging

temperature is from +10 to +25° C.

Note that the two rubber inserts provided

Main parts

(A) = Negative charging and fastening lug

(B) = Positive charging and fastening lug

(C) = Communication link to the vessel

(D) = Location of sensor lamp (rear side of

PI Spread)

(E) = Water switch sensor

(F) = Transverse communication links to

the two Remote sensors

at the bottom of each sensor adapter must

not be replaced with any other types or

designs. It is essential that these inserts

provide a secure cradle for the sensors,

but they must also allow for free water

circulation to allow the sensor’s water

switch to engage. Also, the design of the

inserts allows sand and mud to flow out

when the trawl doors are pulled up from

the water.

Note: Charging sensors at sub-zero

temperatures can create explosive gasses.

Simrad AS assumes no liability for the

improper charging of sensors or the use of

chargers not specified in Simrad’s sensor

charging documentation.

Sensor configuration

You can operate two sets of Twin Spread

sensors, these sets are identified as Twin

Spread 1

and Twin Spread 2.

• Twin Spread 1

uses two Remote

sensors: Remote 1 and Remote 3.

• Twin Spread 2

uses two Remote

sensors: Remote 2 and Remote 4.

On delivery, all Twin Spread sensors are

configured as Twin Spread 1 in Channels

2 and 7, with Fast update rate, and for

use with Remote sensors 1 and 3. The

four Remote sensors can be ordered pre-

programmed from Simrad, but if you wish

to use a Twin Spread 2 set-up you must re-

configure a Twin Spread 1 sensor using the

PI Configurator utility.

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(CD11207B)

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Note: The Twin Spread sensor and the

PI system setup must also correspond,

otherwise the communication will not work.

The sensor update rate controls how often

the sensor reads and reports the door spread.

Three settings are available. Note that a

faster update rate will decrease the battery

life.

Fast (~5,5 sec): Recommended for new

trawl or gear or changes in rigging to

monitor any instabilities or unexpected

changes. This mode provides the shortest

battery life before charging.

Normal (~14 sec): Recommended for

well known trawl, gear and door behavior

with stable situations. Use

this setting during normal

conditions.

System configuration

Sensor configuration: The sensor must

be configured with a unique sensor number.

Select channel number and update rate

according to the sensor’s configuration.

Write down the configuration for future

reference.

Status & Receiver: The Interference

filter must be switched on. Set it to level

9 if you have noise problems from other

hydroacoustic sources. Note that with

the filter on, it will influence the signal

spectrum shown in the Status display.

Sensor filter:

Switch this filter to Light.

Set it to Heavy only if you experience

excessive noise. Position Off will provide

raw data and fastest possible response.

Numerical
presentation

On the PI display, the

distances between the

trawl doors are displayed

in the numeric display.

Two rectangles are

used, one for each distance. If

the distance is increasing or

decreasing, this is shown with

two arrows and the variation in

meters per minute.

When the readings are stable, the digits

are shown in black colour. When the values

are predicted, the digits are grey, and if the

contact is lost, the characters **.* are shown

in grey. The characters

±±.± indicate that

the Twin Spread sensor has lost contact with

the Remote sensor(s), while characters ???

means that the Remote sensors are out of

range.

(A) = Twin Spread sensor set up as sensor

no.1.

(B) = The distancea are measured in meters.

(C) = Current distance between the port

door and the center clump.

Mounting

The Spread and Remote sensors must

be mounted in special adapters on each

trawl door and on the centre clump. These

adapters must be installed aforehand.

Detailed information on how to install the

adapters are provided with the installation

kit.

Installation principle

The PI Twin Spread sensor is mounted

on the port door. One PI Remote sensor is

mounted on the center clump, while the

other Remote sensor is mounted on the

starboard door. It is essential that there is

a clear line of sight between the transverse

communication “eyes” (one on each sensor),

and between the top of the PI Twin Spread

sensor and the hydrophone on the vessel.

1

0.5

S1 [m]

S3 [m]

34.5

68.9

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EE D

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(CD11101T)

(D) = The distance is increasing by 1 meters

per minute.

(E) = Arrows pointing “out” means that the

distance is increasing. Arrows pointing “in”

means that it is decreasing.

(F) = Graphic alarm

(G) = Indicator, lit for every sensor

interrogation.

(H) = Interference symbol.

The bottom numeric display shows the

distance from the port door to the starboard

door, and indicates that the distance

decreases with 0.5 m per minute.

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(CD11207C)

(A) = Port trawl

(B) = Starboard trawl

(C) = Port door

with the PI Twin

Spread sensor

mounted in an

adapter. One acoustic

communication

link is directed

forward towards the

vessel, while two are

directed towards the

two Remote sensors.

(D) = Center clump

with one Remote sensor

(E) = Starboard door

with the other Remote

sensor

(F) = Forward

857-165224 / Rev.B / October 2005

Slow (~34 sec): Recommended to

monitoring a stable situation over time,

focus on door not falling over, broken sweep

lines etc. during the tow. The PI system will

be more sensitive to bad communication

conditions due to slow data update. This

mode provides longest operational battery

life before charging.