Active Sonar Echo Analysis: Monostatic vs. BistaticMisbah Dhuca, Westlake High School, Austin Tx

Supervisor: Jerry Mitchell, Signal and Information Sciences Laboratory, Applied Research Laboratories

Objective: Determine the differences between echoes created by monostatic sonar and bistatic sonar.

Approach: • Monostatic & bistatic active sonar

detecting a 688i attack submarine were simulated in Matlab.

• A set of highlights represented the target• Source and receiver locations, and aspect

of the target were chosen.• Levels were randomly assigned. • TOA of each echo was calculated.• Using an HFM signal as our transmit

signal, we emulated receive processing by cross correlating the transmit signal against itself.

• Plotted the cross correlation on a colormap.

Results: • Differences are in the submarine’s relative

orientation to the source and receiver.• Monostatic plot has hour glass shape • The graphs are identical at 30˚. • Direct blast masking would occur between

150˚ and 210˚ in the bistatic plot• Monostatic highlights approximately time

coincident at 90˚ and 270˚. • Bistatic highlights approximately time

coincident at 150˚ and 210˚.

Results

Highlights were defined relative to the center. Highlights of a 688i submarine: bow; forward hydropane; conning tower; and rudders. Submarine aspect was 0˚.

Monostatic active sonar places the source and receiver in the same position while bistatic sonar places them in different locations.

Source angle: 45˚ Receiver angle: 45˚Distance from source & receiver to center of submarine: 350 meters

Source angle: 30˚ Receiver angle: 120˚Distance from source & receiver to center of submarine: 350 meters

Monostatic BistaticTime of arrivals vs. levels

Each color represents a different level .

Numbers indicate highlight and colors indicate level.

Cross Correlation

Numbers indicate highlight.

Monostatic Bistatic