JW Fishers RMD-1 User manual

Remote Metal Detector
OPERATION MANUAL
RMD-1
012511
JW FISHERS MFG INC
1953 COUNTY ST.
E. TAUNTON, MA 02718 USA
[phone]; [phone]; FAX [phone]
Email: [email protected] WEB: www.jwfishers.com

LEFT BLANK
Coil Set
Underwater
Electronics
Housing Control Box
Mounting Arms
RMD-1 System

SPECIFICATIONS
Sensitivity (in water or air): High Position
• Piece of eight......................................................... 10 in.
• Shotgun ................................................................. 28 in.
• 4" diameter pipe .................................................... 34 in.
• One gallon can ...................................................... 36 in.
• 2' x 4' sheet metal.................................................. 50 in.
• Maximum range..................................................... 62 in.
PERFORMANCE/DESCRIPTION:
• Detection area (standard coil) ...............62 in. deep, 52 in. wide
• Input voltage .......................... 9 -36 vdc, or 120 vac, or 220 vac
• Power consumption.............................................................. 8 w
• Readout ................................................................. Meter, Audio
DIMENSIONS/WEIGHT: Air/Fresh water
• Coil set ............................... 10" x 16" x 5" H ................ 32/2 oz.
• U/W Housing & elect. .......9 1/2" L x 2 1/2"Dia..1.4 lbs/4 oz pos
electronics alone............1 7/8" x 7" x 1 1/2" H.................. 5 oz.
• Surface Control Box ......... 13"L x 13"W x 6"H............... 7.6 lbs.
• Cable ............................. 1/4" Dia x 150-1000' .......... 4-25 lbs.
• Shipping Box ................... 29"L x 25"D x 15"H .......... 25-61 lbs.
MATERIALS/COLOR:
• Underwater housing ............................ High impact PVC/yellow
• Control Box. High impact Underwater Kinetics case, PVC/black
• Cable ................................................. 4 conductor PVC/chrome
• Coil set ........................................... High impact urethane/black
OPTIONS
• Up to 1000 ft. cable.
• RS232 computer output on downstairs electronics.
• Analog output on downstairs electronics (0 to 2.5 or 0 to 5 vdc).
• RS232 computer output with GPS on surface control box.
• Analog output on surface control box (0 to 2.5 or 0 to 5 vdc).
• Input voltage for control box 220 vac and 9-36vdc.
• Different coil sizes (special build).
SENSITIVITY (switch selectable):
i
MAINTENANCE
YourRMD-1wasdesignedtobemaintenancefree. Itisconstructed
of corrosive resistant materials. It is recommended the coil be
rinsed in fresh water after use. It is recommended the control box
bekept outof directsunlightand awayfrom moisture. Closethe lid
when not in use, control box is not water proof. Keep cable
connectors dry. Please write/phone the factory at [phone],
[phone], or E-mail [email protected] if any problems.
LIMITED WARRANTY
Your detector underwent constant inspection during assembly to
insuremany yearsof troublefreeperformance. The RMD-1 hasa
TWOFULL YEARwarranty fromthe dateof purchase. Duringthis
period,your detectorwillbe repairedfreeof chargeshould afailure
occur due to materials or workmanship. The Warranty does not
coverbrokencables orcoils,ordamage duetodroppingor general
misuse.
Shouldserviceberequired,write/phone usexplainingthenatureof
theproblem,andwewillsupplyshippinginstructions. Allrepairsare
madeatourfactory. Repairsbyunauthorizedpersonsmayvoidthe
Warranty.
15

GPS OPTION (used with RS232 Control Box option)
The GPS option allows the boat's GPS to be connected to the
ControlBox. Thisoptionis usedwith theRS232 ControlBoxoption
which will then output the boat's GPS and the RMD's output signal
to a computer.
Attach the output cable from the GPS system to the RMD-1
Control Box.
NOTE: The GPS system must have a serial output, not USB.
There is no adaptor to connect a GPS with USB output to a serial
port.
If the data cable for your GPS has a 9 pin “D” connector on the
end (for a PC serial port), it will connect directly to the “GPS
INPUT” jack on the Control Box. If the data cable for your GPS
has bare wire leads on the end, you will need to splice the
appropriate wires to the cable shown below. If your GPS did not
come with a data cable, one can be obtained from the GPS
retailer or manufacturer. There are usually a variety of cables
available, many also include connections for an external power
source for the GPS. We recommend using an external power
source as using the GPS with the data output consumes a set of
small batteries in a few hours.
INTRODUCTION
The RMD-1 is a high performance Pulse Induction metal detector
which can be attached to almost any ROV or towed underwater
system. PulseinductiontechnologyallowstheRMD-1todetectboth
ferrous and non-ferrous metal objects under the ocean floor while
ignoringmineralizationinthesaltwaterandseabed. TheROVmetal
detector locates and tracks underwater pipelines, finds missing
toolsanddredgeparts,locatesweaponsandunexplodedordnance,
and finds lost treasure.
Pulse detectors have had a major impact on the salvage business.
Their major claim to fame is that they are very sensitive and do not
detect minerals (extreme concentrations of iron ore may give a
modest reading). This lack of mineral detection is an answered
prayer for salt water divers who have to contend with heavy miner-
alizeddeposits on theocean floorwhich producefalse readings on
conventional detectors. Pulse detectors ignore these mineral de-
posits and respond only to metal targets (ferrous and non-ferrous
metal).
HOW PULSE DETECTORS WORK
Pulsedetectorsoperatebytransmittingacontinuousstreamofhigh
energy magnetic pulses (one hundred per second), from the Coil.
Aftereach pulseistransmitted, theunit then"listens"using theCoil
as the receiving antenna.
Coil
Figure 1
When a transmitted pulse hits a metal object, a magnetic field is
inducedintheobject. Thiscauseseddycurrentstoflowinthemetal,
whichinturngeneratesasecondmagneticfield. Thisfieldispicked
upbytheCoil,amplified,andthendisplayedbythemeterandheard
in the speaker/earphone.
1
PULSE
COIL
NOTE: The transmitted
pulse covers a much
larger area than shown
above.
EDDY CURRENTS
COIL COIL
RECEIVE
target
14
Coil Coil
Coil
GPS DATACABLE
red wire for Signal (Data Out)
black wire for Return (Data
Ground)
To RMD-1 Control Box
SOLDER WIRES TO
GPS DATACABLE

pin 1
1
2
3
4
5
Enlarged front view of 5 pin
connector . Pin 2,3 and 5
not used.(PIN END)
fish 1 white
ground black + shield pin 4
Analog output (0-5vdc)
Pin 2,3, and 5 Not used
2
13
45
5 pin socket
in box
5 pin DIN
Connector
in RMD-1
Control Box
REMOTE METAL DETECTOR DESCRIPTION
The RMD-1 system employs two coils molded into rugged ABS
shellsandfirmlyattachedtotheunderwatervehiclewithacorrosive-
proof tubular PVC frame. The frame provides a sturdy mount and
keeps the coils far enough away from the ROV so as not to be
affected by the metal parts. The oval coils produce a detection
envelope which extends 3 to 5 feet into the bottom. The sleek, low
profile coil design minimizes drag and weight on the ROV.
When the coil senses metal it sends a signal to the RMD-1
"downstairs" electronics unit attached to the underwater vehicle.
ThisdownstairselectronicsunitcanproduceRS232output,O-5vdc
output, or a proprietary signal used by the JWF topside control/
readout unit. The output from the downstairs electronics unit can
be transmitted through the ROV's umbilical or a separate cable.
The standard RMD-1 has a topside Control Box which displays the
readoutwithbothameterandaudioalarm. Theclosertheproximity
ofthemetaltarget,thestrongerthereading.Thetopsideunitcanuse
the underwater vehicle's umbilical cable to supply voltage to the
downstairselectronicsunitand toreceivetheoutputsignal fromthe
downstairs unit. The RMD-1 can be powered from 120 vac (stan-
dard) or 220 vac, or 9 - 36 vdc.
The RMD-1 is easy to operate and readily attaches to most any
underwatervehicle.
COIL SIZES
Thedetectionrangeofapulsemetaldetectorisdeterminedtosome
degreebythecoilsize.Largercoilswilldetectlargetargetsdeeper,
but have less sensitivity to the smaller targets. The 10 in x 16 in x 5
incoil,whichisstandardontheRMD-1,isanidealsizefordetecting
both small targets, such as individual coin size objects, and larger
targets to 5 ft deep. Special coil sizes can be built for special
applications.
ANALOG OUTPUT OPTION
The analog output option allows the RMD-1 to be connected to an
external device such as a strip chart recorder or data logger. The
output is 0 to +5.00vdc. The voltage is a representation of the
detection signal strength.
Theanalogoutputuses2 wiresandiswiredtoa5pinDINconnector
on the RMD-1 as Follows:
RS232 WIRING
JWFISHERSMFG
INC
BERKLEY, MA 0 2779
65 AN TH ON Y ST
VISUAL DETECT ION DISP L AY
POWER
AUDIO
JWFISHERSMFG
INC
BERKLEY, MA 02779
65 AN TH ON Y ST
VISUAL DETECTION DISPLAY
POWER
AUDIO
2
13
5 pin DIN
Connector
in RMD-1
Control Box
RS232
White
Black and Shield
RS232
Interface
9 pin "D"
female
connector
pin 2
pin 5
Pins 2,4 and 5 Not used
5 pin socket
in box
1
2
3
45
3
Enlarged front view
of 3 pin connector
(PIN END)
1
2
52
END VIEW
GPS OPTION (used with RS232 Control Box option)
The GPS option allows the boat's GPS to be connected to the
ControlBox. Thisoptionis usedwith theRS232 ControlBoxoption
which will then output the boat's GPS and the RMD's output signal
to a computer.

GAL CAN
36 in
MAX RANGE
62 in
DRAWN
TO SCALE
MAX DETECTION ENVELOPE
(10 in x 16 in x 5 in COIL)
52 in
30 in
RMD-1 SENSITIVITY
ThesensitivityoftheRMD-1 isswitchselectable. Normaloperation
isintheHiposition.Ifyouaretryingtopinpointatargetbutthemeter
goes to full scale, switch to Low or Med sensitivity. The target is
directly below the center of the coil when the meter is at its highest
point(butnotfullscale). WhenoperatinginLowsensitivity,you can
expectdetectionranges aboutonehalfof Hi.Youcan expectthese
detection ranges whether the target is buried under mud, coral,
sand, or rocks.
Sensitivity (in water or air): Hi Position
• Piece of eight......................................................... 10 in.
• Shotgun ................................................................. 28 in.
• 4" diameter pipe .................................................... 34 in.
• One gallon can ...................................................... 36 in.
• 2' x 4' sheet metal.................................................. 50 in.
• Maximum range..................................................... 62 in.
RMD-1 DETECTION ENVELOPE
The detection envelope for the RMD-1 is very large - much larger
thanthe coilwidth/length. The drawingbelow shows thedetection
envelopes (Hi position) for a one gallon can and for the maximum
detection envelope (a very large object).
WhenusingtheRMD-1witha GPSreceiverthefollowingconnection
andpower-upsequencemustbefollowedforproperoperation.
1. Cable up entire system including GPS/Loran C to RMD-1,
RMD-1 to the computer (RS232 interface), and RMD-1
downstairs to RMD-1 control box. Also connect all compo-
nents to their proper power sources.
2. Power-up GPS/Loran C and obtain current position fix.
3. Power-up computer.
4. Power-up RMD-1
5. Initiate data collection program on computer.
IftheRMD-1ispoweredupbeforetheGPShasobtainedthecurrent
position or the GPS interface cable is disconnected, the RS232
interfacewilldefaulttothe"NoPositionAvailable"messageasshown
above.
Ifthe GPS/LoranCloses itspositionfix duringoperation, theRMD-
1 will default to the "No Position Available" message".
If either of these conditions occur correct the fault (re-initialize the
GPS,checkconnections, checkbatterycondition). OncetheGPS/
LoranCisagainfunctioningproperly,powerdowntheRMD-1, wait
five seconds and power up the RMD-1. The position information
shouldnowbepresent.
RS232ONDOWNSTAIRSELECTRONICSOPTION
WiththeRS-232option,thedownstairselectronicscanbeconnected
toanycomputerordatarecorderequippedwithanRS-232input.The
specificationoftheinterfaceisasfollows:8bitASCIIdata,4800baud
rate (custom baud rates are available), 1 stop bit and no parity bit.
The message relays the signal strength from the RMD expressed
from0to5,000millivolt(0to5.000volts).Thecompletemessageis
repeatedcontinuouslywithno delaybetween messages.
The message sent on the RS-232 output is as follows:
(Note: Themessage length canvary asshown)
RMD=95mv<cr><lf>
RMD=3270mv<cr><lf>
RMD=5000mv<cr><lf>
•Thebaselinereading(nometalpresent)isapproximately100mv.
Seepage9forconnectioninformation.
3
12

RS232 /GPS OPTION
WiththeRS232optiontheRMD-1ControlBoxcanbeconnectedto
anycomputer ordata recorderequipped withan RS232input. The
specification of the interface is as follows: 8 bit, 4800 baud rate, 1
stop bit, and no parity bit.
TheGPS/Loran Cinterface allowsthe ships positioninformation to
beinputintotheRMD-1. TheRMD-1thenreformatstheinformation,
combinesitwiththesignalstrengthreadingfromthesearchcoil,and
sends it to an external computer via the RS232 interface.
Any GPS or Loran C receiver equipped with a NMEA 0183 output
canbeusedwiththeRMD-1. Ifyouarenotsureifyourreceiverhas
NMEA0183output,checkitsmanualorcallthemanufacturer. You
mayfindthatyouhavetotellyourGPSreceivertosendoutthe0183
information (refer to your GPS manual). If given a choice, select
0183Aor0183Cformat. Bothversionsincludethelatitude/longitude
message format called GLL. The RMD-1 can also receive the
message format called GGA, if the message GLL is not available.
The RMD-1 automatically checks for the presence of either mes-
sage on power-up.
The sample message sent on the RS232 interface is as follows:
Position 4151.745353, N, 07102.394576, W <cr>
RMD= 3270mv <cr> <cr>.
Where the "Position" is the latitude and longitude coordinates from
the GPS or Loran C receiver and "RMD" is the detection signal
strengthsexpressedfrom0to5,000millivolts(0to5.000volts). The
complete message is repeated once per second.
If a GPS or Loran C is not being used, or if the GPS or Loran C
messageisnotbeingproperlyreceivedbytheRMD-1,themessage
will be as follows:
NO POSITION AVAILABLE <cr>
RMD = 3270mv <cr> <cr>.
4
UNDERWATER HOUSING: Contains downstairs electronics board. Can be powered from surface Control Box(standard)orfromlocalROVpower (9-36vdcat8w).Electronicsboardcan beremovedfrom housing and mounted in ROV. Electronics board output is RS232, or analog, or a proprietary sig- nal to surface Control Box (standard).
SURFACE CONTROL BOX: Contains switches and controls for operating the system. When metalisdetectedby the coil, the meter in the Control Box swings up and the audio alarm sounds off. Control Box also has an op- tional RS232 and analog output for computer or chart recorder connection. System can be op- erated without the Control Box byapplying powerdirectlyto the underwater housing.
JWFISHERSMFG INC
BERKLEY, MA 0 2779
65 AN TH ON Y ST
VISUAL DETECT ION DISP L AY
POWER
AUDIO
Underwater
Housing Up to a 1,000 foot of cable
Surface Control
Box
OutPut
(RS232 or Analog)
Input Power
(120/240 vac
or 9-36 vdc)
2 or 4 wires
RMD-1 SYSTEM CONFIGURATION
CABLE: Can use umbilical cable from ROVoraseparatecable. A 4 wirecableisrequiredifpower to the U/W housing electron- ics is from the surface; 2 wires if power is from ROV.
COIL: High noise immunity coil set. Standard coil set is 10" x 16" x 5". Larger coils are available by special order. Full ocean depth coils are also available.
4 foot cable
standard

RMD-1 CONTROL BOX
Theheartofthesystemisthecontrolboxwhichcontainsallcontrols
and indicators for the system:
• Meter Indicatesthe presence ofmetal by swing-
ing to the right. The closer the metal is to
the coil, the further it will go to the right.
• Speaker When the meter moves past .2 , the
speakersounds off. The higherthe meter
goes, the higher the pitch (frequency) out
of the speaker.
• Volume Control Adjusts the volume out of the speaker or
earphone.
• Earphone Jack Accepts a standard 1/4" earphone plug
(stereo or mono). Speaker output is si-
lenced when earphones are plugged in.
• RS232 Output With this option the RMD-1 can be con-
nected to any computer or data recorder
with a RS232 input.
MOUNTING AND CALIBRATION
The RMD-1 has been factory calibrated for proper operation when mounted on a
JW Fishers ROV or other non-metallic host platform. In other applications, the
search coils should be mounted as far from metallic components as possible. Only
nylon or 316 stainless steel fasteners may be used near the search coils.
Before permanently mounting the search coils, test the RMD system to insure that
it will operate properly with the search coils in the chosen location. When testing,
the host platform and search coils must be clear of other metals (at least 6 ft from
the search coils). To check for proper operation, test each sensitivity setting (low,
medium, and high). In each setting, the zero adjust knob should be able to set the
meter between 1 and 2, the normal operating range. If using the RS232 output, the
reading should be close to +0.1vdc (+100mv dc).
If the above condition can not be met, try repositioning the search coils for the
lowest meter reading. Once the best location is found, secure the search coils in
the chosen position. Retest the system. If the zero adjust knob cannot zero the
meter in each sensitivity setting, complete the following procedure to calibrate the
downstairs board.
Equipment needed: Phillips screw driver, small flat blade screwdriver, DC volt
meter able to read down to 0.1 vdc. If the RS 232 output will be used, the readings
from this test may be observed on the PC display instead of the dc volt meter.
1) Remove the (2) 4-40 x 3/8" flat head screws from the underwater housing.
2) Slide the cable end out of the housing.
3) Rest the circuit board on a non-metallic surface. Do not unplug any cables.
4) Turn on the RMD system.
5) Measure the voltage on the right pad of J2. Connect the (-) lead of the meter to
pin 2 of JP6 (green wire).
6) Turn the trimpot R37 with the small flat blade screwdriver. Turn in the direction
that causes the voltmeter reading to decrease. DO NOT ADJUST ANY
OTHERTRIMPOTS
7) Adjust R37 until the voltmeter or PC display reads +0.10vdc (+100mv).
8) Test the RMD system again. The zero adjust knob should be able to zero the
meter in all sensitivity switch positions. Slowly approach the search coils from
below the 'Bottom Coil' with a metal object. The voltage should begin to
increase as the object is brought closer to the 'Bottom Coil'. Please note that
the detection envelope is non-linear. The voltage change will be very small
(50-100mv) when the object is at the outer edge of the detection envelope.
The voltage change will be greater as the object is brought closer to the search
coils.
9) Reinstall the underwater housing and o-ring. Be sure the o-ring and its seats
are clean. Reinstall the (2) 4-40 x 3/8" flat head screws. Do not overtighten.
10
5
Power Cord
Speaker
Volume Control
Earphone Jack
Analog Output (option)
or
GPS Input (if RS232 option) RS232 Output
(option)
Coil
Selection
Switch
Zero Adjust
Power On LED
Power Switch
Meter

• GPS Input If the RS232 output option is selected then
this connector is used to input GPS data
fromyour GPS.It isthen outputtedwith the
RS232 data string.
or
• Analog Output With this option a 0-2.5 vdc (or 0-5 vdc)
voltage is provided. This output tracks the
meter movement.
• Cable Jack The cable from the "downstairs electronics
unit" plugs into this jack.
• On/Off Switch Turns power (24vdc) on in the system.
• Power on LED Lights when power is on.
• Sensitivity Switch A three position switch which selects the
sensitivity of the detector:
Low Pos. The unit is operating in LOW sensitivity
(about 1/2 of HI).
Med Pos. The unit is operating in MED sensitivity
(about 2/3 of HI).
Hi Pos. The unit is operating on HI sensitivity (nor-
mal operating mode).
9 6
RMD-1 DOWNSTAIRS BOARD CONNECTIONS
RMD-1 DOWNSTAIRS ELECTRONICS
1
2
1
2
Bottom Coil
Top Coil
JP5
JP4
Blk
Yellow
Blk
Green
R33
R10
R16
PS1 1
24
3
5
1
2Output
JP6
Green
White R37
R56
U6
System Disable
JP1
1 2
J1
J4 J2
J3
JP7
60 Hz
50 Hz
9-36 vdc input
1
2
Black
Red
JP-1 SYSTEM DISABLE JP-4 TOP COIL JP-6 OUTPUT
1. (+) 1. (+) 1. Signal 2. Signal Return 2. GND 2. GND
JP-3 DC POWER INPUT (9-36 vdc) JP-5 BOTTOM COIL JP-7 FILTER JUMPER
1. (+) 1. GND or SD COMMAND 2. (-) 2. (+)

LEFT BLANK
OPERATION/CHECKOUT
- Position the coil outside and 5-6' away from any metal.
- Plug the cable from the underwater electronics board into the
control box.
- Connect power to the system.
- Turn the control box Power Switch on and note that the POWER
ON LED is illuminated.
- Turn the Sensitivity Switch to HI position.
- TurntheZEROADJUSTknobuntilmeterreadsapproximately.1.
- Thesystem isreadytogo. PeriodicadjustmentoftheZeroAdjust
knob may be necessary.
DETECTING METAL
As metal passes below the lower Coil, the needle swings up. At
abouta.2meterreadingtheaudiosoundsoffandincreasesinpitch
(frequency) as the needle swings higher. Maximum meter swing
occurswhenthetargetisdirectlybelowthecenteroftheCoil. Asyou
go past the target, the needle returns to .1 and the audio stops.
Runsome testsout ofthe waterwith ametal target(gal can isfine)
togetthefeelofthedetectionpattern. Thereisnoneedtomovethe
coil, simply move the target around (below) the coil set.
The upper coil is the noise cancellation coil. As metal is brought
above this coil it causes the meter to go down. If metal is brought
fromthe sideof the coilset, thetop coilcancels outthe detectionof
thebottom coil. Thisfeature allowsthe coilset tobe locatedneara
metalobject withoutdetecting it. However,ifthemetal istooclose
to the side of the coil it will reduce sensitivity to other targets. It is
whenametalobjectpassesbelowtheplaneofthelowercoilthatthe
target is detected.
78