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11 4

THEORY OF OPERATION

When the pinger is turned on (manually, or automatically when the

pinger is put in the water) a continuous series of acoustic pulses

(sound waves) are emitted from the transducer (black end) of the

pinger. The pulses are of very short duration. The pulse length is

measured in milliseconds (ms), and travel out from the transducer

in all directions.

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4 ms (pulse length)

1 sec

(one sec between pulses)

Pulse

amplitude

The operator has complete control of the output signal by “push on”

jumpers on the electronics board. These jumpers are set prior to

deployment of the pinger.

1) The pulse length (4 ms shown above) is operator adjustable

from 1 to 5 ms (may vary with model). The longer the pulse, the

further the signal will travel in the water; but the longer pulse

consumes more power and shortens battery life.

2) The repetition rate (sec between pulses) is also operator ad-

justable from .5 sec between pulses to 2 sec between pulses (1

sec between pulses shown above). A shorter rep rate does not

increase range; but it is easier to locate a pinger operating at .5

sec between pulses than one operating at two seconds between

pulses. A pinger operating at .5 sec consumes twice the battery

power of a pinger operating at a 1 sec rep rate.

3) Power output (pulse amplitude) is also operator adjustable

from .1 to 8 watts (may vary with model). The higher the output

power the farther the signal will travel through the water. Dou-

bling the output power increases the distance; but does not double

the distance. Doubling the output power reduces battery life in

half.

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JW Fishers SFP-1 User Manual

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