Null Shifting With Fixed Delays
Abstract
Null shifting over a 1 GHz bandwidth is demonstrated using a fiber optic and transversal filter. The null depth for our system is greater than 70 dB measured with a 10KHz 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 centimeter 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 effected by using ths approach. Keywords: Optical signal processing; Fiber optics; Integrated optics.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1990
- Accession Number
- ADA223941
Entities
People
- Debra M. Gookin
- Mark H. Berry