EVALUATING THE EFFECTIVENESS OF HYPERSTACKING

FOR GPR SURVEYS

SAGEEP 2016

Dr. Jeffrey Feigin and Dr. David Cist

Geophysical Survey Systems Inc.Nashua, NH

Objective:

Compare performance in data quality of

Equivalent time sampling (ETS)

Hyperstacking (HS)

Defining terms:

Conventional Equivalent time sampling (ETS)One data sample per Transmit Pulse.

Hyperstacking (HS): A variant of Real Time Sampling (RTS)Many samples per Transmit Pulse.

Equivalent Time Sampling (ETS)

Response 1

Response 2

Response 3

Response 4

Subsampled Response

Response 5

Noise Free

with

noi

se

Response N

From response 1 From response N

Defining terms:

Conventional Equivalent time sampling (ETS)One data sample per Transmit Pulse.

Hyperstacking (HS): A variant of Real Time Sampling (RTS)Many samples per Transmit Pulse.

Real Time Stacking (RTS)

How is HS different from RTS?

HS is a subclass of RTS which incorporates Dithering Spreads energy to make full use of FCC limits.Benefits:

Reduced System noise

Reduced Broadcast noise.

Operates at a faster rate than standard RTS

Now can operate at high PRFs and still comply

Cost effective

Test Method:

Collect data from ETS and HS systems over the same profile line using the same cart and using similar frequencies (400MHz) Same processing

Collect these data in different locations Low Loss soils High Loss soils High noise environment

Compare the images qualitatively

Low Loss Soils

ETS HS

ETS HS

Shallow Depth (High resolution)

HS “350”

ETS at 800 MHz

High Loss SoilsHSETS

High Loss SoilsHSETS

ETS HS

High Noise Environment

Surveying close to a cell tower.

High Noise Environment

Surveying close to a cell tower.

ETS HS

High Noise Environment

Surveying close to a cell tower.

ETS HS

Conclusions Low Loss soils

• HS penetrates significantly more deeply than ETS systems.• Weak target reflections are brought out of the noise.

High Loss soilsHS performs about the same as ETS.

High Interference (Broadcast, Cellular, etc.) is randomized and Averaged Out.

Thank You