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Proceedings Paper

Null shifting with fixed delays
Author(s): Mark H. Berry; Debra M. Gookin
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Paper Abstract

Null shifting over a 1 GHz bandwidth is demonstrated using a fiber-optic and integrated-optic transversal filter. The null depth for this system is greater than 70 dB, measured with a 10-KHz IF bandwidth. The null shifting is achieved by varying the tap weight values. Null shifting in the response of a transversal filter is directly related to null steering for a radar direction finder. The fixed delays consist of optical fibers cut at 10-cm increments. Integrated optical 2 x 2 couplers are used as the tap weights. The weighting is controlled by an applied voltage. The depth of the null is limited by the dynamic range of the source/detector combination. Ordinary fixed weight fiber-optic transversal filters are subject to dynamic range and bandwidth limitations due to errors in cutting the fiber lengths. This problem can be remedied by using variable taps to shift the null frequency. The null depth and resolution is not detrimentally affected by using this approach.

Paper Details

Date Published: 1 June 1990
PDF: 5 pages
Proc. SPIE 1217, Optoelectronic Signal Processing for Phased-Array Antennas II, (1 June 1990); doi: 10.1117/12.18165
Show Author Affiliations
Mark H. Berry, Naval Ocean Systems Ctr. (United States)
Debra M. Gookin, Naval Ocean Systems Ctr. (United States)

Published in SPIE Proceedings Vol. 1217:
Optoelectronic Signal Processing for Phased-Array Antennas II
Brian M. Hendrickson; Gerhard A. Koepf, Editor(s)

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