Accession Number:

ADA071186

Title:

CHIRP Versus BURST Sonar Resolution Techniques for Classification During Detection

Descriptive Note:

Corporate Author:

DALMO VICTOR TEXTRON BELMONT CA

Personal Author(s):

• Baker, Richard E.

Report Date:

1969-01-01

Pagination or Media Count:

11.0

Abstract:

A previous Dalmo Victor report, R-2850-2931, proposed the CHIRP pulse compression technique as most adequately resolving detection range, classification and range rate problems for search sonars. This report qualitatively evaluates the effects of propagation non-linearities and Fresnel zone target scattering interference on CHIRP resolution. Comparisons are made to a BURST short pulse train system. For equal resolution, both techniques require equal bandwidths and similar spectral amplitude distributions. BURST resolves signals from different range cells by phase or time difference alone CHIRP by both time and frequency. Propagation non-linearities cause similar coherence loss and resolution broadening. Scattering is a linear process. CHIRP resolves overlapping long pulse echoes by superposition of time-frequency separated signals. It is concluded that CHIRP provides resolution equivalent to BURST for a given sonar bandwidth. CHIRP permits use of a long, low data rate, detection pulse. In addition, the coherent integration used in a CHIRP system provides a greater target detection range than can be achieved with the non-coherent integration used in a BURST system, for the same average power. CHIRP also permits removal of range rate by triggering the classification display sweep at receipt of the first compressed CHIRP echo.

Descriptors:

• *SONAR PULSES
• BURST TRANSMISSION
• PULSE COMPRESSION
• RESOLUTION
• SEARCH SONAR
• SIGNAL PROCESSING
• SONAR TARGETS
• SUBMARINE DETECTION
• TARGET CLASSIFICATION
• TRANSFER FUNCTIONS

Subject Categories:

• Undersea and Antisubmarine Warfare
• Acoustic Detection and Detectors

Distribution Statement:

APPROVED FOR PUBLIC RELEASE