DSU3

D I G I TA L S E N S O R U N I T S

Ahead of the CurveSM

DSU3
The 428XL offers all new hardware and software which is specifically

designed to address the growing demands of the geophysical industry

for even larger channel counts, high performance digital receivers, and

greater layout flexibility. With the introduction of the 428XL, the DSU3 has

been introduced with enhanced capabilities. The Digital Sensor Unit (DSU)

enhancements include: insensitivity to tilt, reduced power consumption

and redesigned packaging to move sensors deeper into the ground when

planted, lowering the profile of the DSU3 and improving coupling.

DSU (Digital Sen Higher Productivity
Three Component Digital Sensors
The DSU3 is an integrated package made up of station electronics and three digital accelerometers based on MEMS (Micro-
machined Electro-Mechanical Sensor) technology with low power consumption and full functionality at any tilt angle. The DSU
has proven to be high-performance, power-efficient and reliable in all operations.

The DSU3 digitizes data from a single ground station and its three orthogonal components allow it to accurately record
the ground motion on all three axes. This is a significant improvement over traditional analog P-wave geophones that
only record the vertical component. Utilization of the full seismic wave field, when accurately recorded and processed,
enhances the seismic interpretation and reservoir characterization to help reduce F & D costs.

Excellent Compatibility
Links of DSUs are designed to be used in conjunction with the 400 Series family of field systems. Links of FDUs with
analog sensors and DSUs with digital accelerometers may be mixed within the same recording spread under the control
of a single central unit, and without additional specific hardware. The DSU is fully supported by all software functions and
telemetry flexibility in the 428XL.

Full Sensor Testability

The DSU3, as is the case with all electronics in the 400 Series family, is fully field testable. Thanks to the built-in
accelerometer, the sensor can be tested for distortion, gain, phase accuracy and crosstalk as well as for gravity, noise
and tilt. This full set of tests can be cycled automatically and on a continuous basis throughout the production day thus
ensuring the highest quality signal on every shot. Results are recorded and time stamped on the header information of the
seismic records.

Applications of DSU Technology

Field proven to great effect worldwide in reservoir monitoring projects, DSUs are providing information with regard to
the structure and fracture characteristics of producing fields that were not available with the previous generations of
equipment. Existing fields believed to be exhausted can once again become strong producers through new generations of
full wave digital sensors providing improved characterization, higher resolution images and as a result, greater recovery.
No matter the difficulty of the terrain to image or the challenge of the target to reach; the high fidelity and broader
bandwidth achieved from DSU point receivers, recording the full range of compressional and shear wave motion, allow for a
higher quality image at a lower acquisition cost.

For 50 years Sercel has been at the cutting-edge of seismic technology and innovation. Whether the job calls for acquisition
systems, digital sensors, vibrators or associated QC software, Sercel equipment is fully integrated to form a complete
seismic acquisition package. Designed to integrate with future evolutions, these systems will fulfill all of today’s needs,
and will continue to meet them far into the future.

As customers demand more accurate, higher-resolution data, make sure you’re Ahead of the Curve with the best possible
system in the industry.

Omni-directional sensors, minimal battery use, and ease of deployment all result in highly productive seismic field
operations.
nsor Unit) Equipment Profile
Geophysical Benefits DSU3
Functions: • Acceleration measurement and data
• Excellent vector fidelity
transmission with CRC control

• Broad bandwidth • 24 bits digital acquisition

Full scale: 5 m/s2

• Shear wave structural imaging
Tilt max value: +/- 180°

- Structures below gas clouds Noise (10-200Hz): 0.4 μm/s2/√Hz

System dynamic range: 120 dB @ 4 ms

• Improved reservoir characterization
Sampling rate: 4, 2, 1, 0.5, 0.25 ms

- Lithology delineation Bandwidth: 0 - 800 Hz (up to 1600 Hz with degraded

specifications)
- Discriminate lithology & saturation effects Distortion: -90 dB

Amplitude calibration
- Monitor fluid variations (pressure, saturation)
accuracy: +/- 0.25%

- Open fracture trends & density Orthogonality

calibration accuracy: +/- 0.25%

• High frequency preservation: no intra-array statics Power consumption: 285 mW @ 8 Mbps, 300 mW @ 16 Mbps

Static sensor tests: Tilt, gravity, noise

• Noise attenuation potential with polarization filtering
Dynamic sensor tests: Distortion, gain, phase

- no unaliased ground-roll required Dimensions (HxWxD): 159.2 x 70 x 194 mm

(6.2 x 2.7 x 7.6 in.)
• Isotropic recording: no array filtering Weight: 0.43 kg (0.9 lbs.)

Operating
temperatures: -40° to +70°C

Storage temperatures: -40° to +70°C

Operational Benefits
Water depth: 15 m (for WPSR)
• Low system weight
1 m (for ST+)

• Omni-tilt

• Better plants with improved coupling since leveling is not required

• Reduced effort field deployment

• Fewer connections required

• Reduced possibility of wiring errors

• Reduced power consumption

• Sensor quality control

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DSU3 New Features and Benefits
Omni-Tilt
New features of the DSU3 include insensitivity to tilt, improved packaging, and
reduced power consumption.

The orthogonally configured digital sensors inside the DSU3 make it possible for
them to be deployed in snow, desert, on hills, or wherever at any tilt angle. The
sensors detect the effects of earth’s gravitational pull on each sensor allowing
them to identify their orientation in relation to a vertical plant, and make the
appropriate corrections.

Redesigned Packaging
The packaging of the DSU3 has been redesigned to move the sensors deeper into the
ground when planted. Lowering the profile of the unit provides greater protection from
surface wind noise susceptibility and optimal ground coupling.

Reduced Power Needs

Very low power consumption (as low as 265mW for the 3 sensors and the
associated data transmission and test circuitry package) allows seamless
deployment of thousands of units and fewer trips back to the field during
The DSU has proven to be operations for battery maintenance and recharging. Efficient power management
with only one battery required for every 40 3C stations in the ground improves
high-performance, crew logistics (A 10,000 station, 30,000 channel crew uses only 250 batteries.)
The batteries used may be any 12V battery whose size and type can be selected
power-efficient and
to suit the local environment or temperature.
reliable in all operations.
Omni-directional sensors, minimal battery use, and ease of deployment all result
in highly productive seismic field operations.

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