BATTERY SELECTION
The PULSE 12 draws approximately .3 amp at 24v. Two car type
batteries will last several days of continuous use. For good
portability, two motorcycle type batteries can be used, with a
minimum of 8 hours between charges. Battery status can be
checked at any time by pressing the Batt Ck switch upward and
observing the Fish 1 meter for a reading of .7 to 1.
MAINTENANCE
Please write/phone the factory at (508) 822-7330 if any problems.
RS232 /GPS/ANALOG OPTION
With the RS232 option the Pulse 12 can be connected to any
computer or data recorder equipped with an RS232 input. The
specification of the interface is as follows: 8 bit, 4800 baud rate, 1
stop bit, and no parity bit.
The GPS/Loran C interface allows the ships position information to
be input into the Pulse 12. The Pulse 12 then reformats the
information, combines it with the signal strength readings from the
towfish, and sends it to an external computer via the RS232
interface.
Any GPS or Loran C receiver equipped with a NMEA 0183 output
can be used with the Pulse 12. If you are not sure if your receiver
has NMEA 0183 output, check its manual or call the manufacturer.
You may find that you have to tell your GPS receiver to send out the
0183 information (refer to your GPS manual). If given a choice,
select 0183A or 0183C format. Both versions include the latitude/
longitude message format called GLL. The Pulse 12 can also
receive the message format called GGA, if the message GLL is not
available. The Pulse 12 automatically checks for the presence of
either message on power-up.
The sample message sent on the RS232 interface is as follows:
@Position, 4151.745353, N, 07102.394576, W,
Fish 1=,3270, Fish 2=,1650,Fish 3=,350<cr><lf>
Where the position is the latitude and longitude coordinates from the
GPS or Loran C receiver and "Fish 1", "Fish 2", and "Fish 3" are the
detection signal strengths expressed from 0 to 5,000 millivolts (0 to
5.000 volts). The complete message is repeated once per second.
GAL CAN
6'
MAX RANGE
16'
DRAWN
TO SCALE
DETECTION
AREA FOR
SINGLE COIL
9'
24'
MAX DETECTION ENVELOPE ( fresh water )
PULSE 12 SENSITIVITY
The sensitivity of the Pulse 12 is switch selectable and is dependent
on whether it is operating in fresh or salt water. If operating in fresh
water (or on land) you can expect detection ranges as indicated
under
Fresh
in the chart below. When operating in salt water, you
can expect detection ranges as indicated under
Salt
in the chart
below. When operating in salt water, a second switch
Sample
Pulse Delay
is used to "adjust out" the salt water impact on the large
Pulse 12 coil. The Sample Pulse Delay setting does impact the
detection range on smaller targets, but has little impact on larger
targets. You can expect these detection ranges whether the target
is buried under mud, coral, sand, or rocks.
Sensitivity (in water):
Fresh
Salt
Sample Pulse Delay
0
0
5
• Piece of eight ............................... 17 in ................. 9 in. ... 4 in.
• 25 lb. lead ingot ........................... 40 in ............... 32 in. . 31 in.
• One gallon can ............................... 6 ft ................. 4 ft. .... 4 ft.
• Automobile ................................... 13 ft ............... 12 ft. .. 12 ft.
• Ship (max. range) ......................... 16 ft ............... 14 ft. .. 14 ft.
PULSE 12 DETECTION ENVELOPE
The detection envelope for the PULSE 12 is very large - much larger
than the coil width/length. Figures 4a,b shows the fresh and salt
water detection envelopes for a one gallon can and for the maxi-
mum detection envelope (a very large object). Though it is not
shown, the envelopes exist above the coil as well as below.
3
Figure 4a
10
