Accession Number:

ADB063872

Title:

Wideband, Interferometric Spectrum Analyzer.

Descriptive Note:

Final rept. May 80-May 81,

Corporate Author:

HARRIS CORP MELBOURNE FL

Personal Author(s):

• Shah, Manhar L.

Report Date:

1981-08-01

Pagination or Media Count:

98.0

Abstract:

An interferometric acousto-optic spectrum analyzer system is configured in which the light signal is made proportional to the amplitude of the RF signal, thereby doubling the dynamic range in dB over the Bragg cell spectrum analyzer. In an experimental system a 40 increase in dynamic range was observed. Several schemes to generate a reference beam and obtain constant frequency interference beats are discussed. The theoretical and experimental dynamic range of noninterferometric and interferometric acousto-optic Bragg cell spectrum analyzers are determined. Experimentally, we have observed 58 dB dynamic range for a cw signal and 54 dB dynamic range for a 5 micro sec pulse signal. A short pulse of 60 ns length was detected with 20 dB dynamic range, 100 probability of intercept and less than 1 micro sec time-of-arrival accuracy. The system bandwidth was close to 250 MHz with 3.5 MHz frequency resolution. The spuriour level was below 50 dB. The system used a 5 mW HeNe laser in a Mach-Zehnder configuration. Discrete Si photodetectors with a fiber optic array were used in the experiment.

Descriptors:

• *SPECTRUM ANALYZERS
• *PHOTODETECTORS
• *ACOUSTOOPTICS
• LIGHT MODULATORS
• BRAGG ANGLE
• REAL TIME
• BROADBAND
• DYNAMIC RANGE
• RADIOFREQUENCY
• FREQUENCY MODULATION
• OPTICAL INTERFEROMETERS
• VOLTAGE CONTROLLED OSCILLATORS

Subject Categories:

• Test Facilities, Equipment and Methods
• Optical Detection and Detectors

Distribution Statement:

APPROVED FOR PUBLIC RELEASE