Atec G-882TVG User Manual

G-882TVG CESIUM MAGNETOMETER

& TRANSVERSE GRADIOMETER

Marine Search Applications for UXO, pipelines, lost

•

objects with Multi-Sensor Array Capability

• High Sensitivity ─ 0.004 nT/sq-rt-Hz RMS with dual

CM−221 Larmor Counters

• Very Low Heading Error ─ ±0.25nT over 360˚

equatorial and polar spins

• Versatility ─ CM-221 counter includes 8 channel 12

bit A to D converters for real time internal
diagnostics, digital data stream concatenation,
and short, long or telemetry over coax options

• Reliability and Ruggedness – Cesium

magnetometers never need be returned to factory
for calibration or tuning. Designed for tough
environmental conditions and high “G” loads

• Gradiometer arrays offering simultaneous operation of up to 8 separate sensors using the

designed-in multi-sensor data concatenation of the CM-221 internal counter

• Geometrics offers complete turnkey systems including tow cables, gradiometer wing, digital data

acquisition systems with real time anomaly detection, GPS navigation and post acquisition data
processing software and training.

The Geometrics Model G-882TVG Transverse
Gradiometer system mates the well- proven high­performance cesium sensor with dual high
sensitivity and high speed CM-221 Larmor
Counters. This advanced integrated
magnetometer system provides unmatched
versatility in performance, with a wide sensor
separation for maximum target detection efficiency
and survey cost effectiveness.

The system comprises a transverse wing and two
G-882 Cesium Vapor magnetometer fish with
stabilizer weights and fins. Tow cables may be up
to 150m in length with standard power supply or
up to 700m with a high capacity voltage sense
supply. Depth sensors provide gradiometer
attitude and depth information to the operator
depth and an echo-sounder altimeter provides
height above sea floor for proper system flight
control.

Dual sensors are synchronized to 1ms sampling
and data is transmitted via RS-232 for recording by
any standard PC computer using our industry
standard MagLogLite software. High sample and
data transmission rates (up to 40 samples per
second) are standard.

The G-882G provides sensitivities of 0.004 nT/√Hz
RMS or approximately 0.01 nT P−P at 10 Hz,
selectable via software command for detection of
the smallest anomalies. MagLog software
computes the transverse difference for display and
analysis in real time, using the customer supplied
GPS for interpolation and target positioning.

The system's high performance is excellent for the
detection and delineation of cables, pipelines,
environmental, archaeological or military UXO and
EOD targets.

/

Software

Geometrics supplies MagMap2000 and
MagPick with each system for analysis and
interpretation of total field and gradient data.
Analytical signal is computed from the
transverse gradient, longitudinal time gradient
and computed vertical gradient to give a time­variation free data set for contouring and
plotting of anomaly targets. Simultaneous dual
inversion routines in MagPick produce a
located target worksheet with models including
object latitude-longitude position and depth of
burial. Download

ftp://geom.geometrics.com/pub/mag/Software/
Posters.zip for more information

MODEL G-882TVG MARINE CESIUM GRADIOMETER SPECIFICATIONS

OPERATING PRINCIPLE:
OPERATING RANGE:
OPERATING ZONES:

SENSITIVITY WITH CM-221 COUNTER:

SAMPLE RATE:
HEADING ERROR:
ABSOLUTE ACCURACY:
OUTPUT:

MECHANICAL:

CABLES:

OPERATING TEMPERATURE:
STORAGE TEMPERATURE:
ALTITUDE:
DEPTH RATING:
POWER:
ACCESSORIES:

Standard: Power/RS-232 multiconductor cable (electronics to power/data

Optional:

Logging Software MagLog (Logs GPS and Mag, shows trackplot, mag profile, other

Processing software MagMap2000, MagPick

SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE 05/09

GEOMETRICS EUROPE

20 Eden Way, Pages Industrial Park, Leighton Buzzard LU7 4TZ, UK
Tel: [phone] – Fax: [phone]
Email: [e-mail]

Self-oscillating split-beam cesium vapor (non-radioactive)
20,000 to 100,000 nT
The earth’s field vector should be at an angle greater than 10° from

the sensor’s equator and greater than 10° from the sensor’s long
axis. Automatic hemisphere switching.
<0.004 nT
Hz) sample rate (90% of all readings falling within the P-P envelope)

Up to 40Hz in 100ms increments
<0.25 nT over entire 360° equatorial and polar spins

<3 nT throughout range
Cycle of Larmor frequency = 3.498572 Hz/nT, RS-232 data at 115K

baud, concatenated data streams from 2 to 8 sensors depending on
sample rate
Total weight including 70kg (155 lbs) including two fish, wing and
tow cable. Sensor separation is 1. 5m for maximum gradient
Vectran Reinforced multi-conductor tow cable. Breaking strength
3,600 lbs, 0.48 in OD, 500 ft standard maximum. Up to 2100 ft with
variable voltage supply. 200 ft (60m) weighs 17 lbs (7.7 kg).

-30°F to +122°F (-35°C to +50°C)

-48°F to +158°F (-45°C to +70°C)
Up to 30,000 ft (9,000 m)

Depth rated to 4,000 psi (2,700m)
115/220 VAC, 60 watts at turn-on and 40 watts thereafter

junction box with 9 pin RS-232 connector and power lugs), lengths
to be specified, operation manual and reusable shipping and storage
containers

data )

GEOMETRICS INC. 2190 Fortune Drive, San Jose, California 95131, USA

Tel: [phone] – Fax: [phone]
Email: [e-mail]

sq-rt-Hz RMS. Typically 0.01 nT P-P at a 0.1 second (10