Wide-Band Signal Processing Using the Two-Beam Surface Acoustic Wave Acoustooptic Time Integrating Correlator

Abstract

A bstruet-A new acoustooptic architecture for performing real-time correlation of tigh-frequency wide-band signals has beerr developed. It uses a surface-acoustic-wave (SAW) delay line, and features the optical interference of two coherent light beams which have been Bra&-diffracted by SAW's propagating in the tine. The signal muttipiication, and subsequent time integration of the product formed, is performed by a photodiode array which deteets the diffracted tight. This arehitectrrre has achieved tirstebandwidths products exceeding 106 (34 MHz X 30 ins), and has several attributes which make it particularly well suited for use as a spread-spectrum signal processor. These include linearity of operation, large dynamic range, a large time aperture over which the correlation can be observed, and the ability to determine the center frequency and bandwidth of the signals. A correlator with this architecture has been used to detect a number of wide-band spread-spectrum signals. Its suitability for nse as a signal processor in several spread-spectrum systems is considered. I. INTRODUCTION EVERAL present-day radio systems munications, navigation, and radar used for commake use of spread-spectrum techniques to obtain greater range, multi-Manuscript

Analysis of DNA sequences by an optical time-integrating correlator

“…perform the correlation of two signals. The many possible ways to build TICs are well documented in the literature [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] and good review papers are available [15,21,27].…”

“…It is also desirable to emphasize the correlation peak by removing the pedestal shown in Figure 3. The technique used here involves subtraction of two successive frames collected by the detector with a 180* phase shift on one of the signals applied to the Bragg cells for the collection of the second frame [8,21]. The effective integration time generated by the phase-shift method is twice the integration time of the detector array.…”

Dynamic range of quadrature radio-frequency time-integrating acousto-optic correlator

“…But the presence of a spatial carrier frequency in its output charge distribution complicates information reading and restricts possible area of application. The spatial carrier can be removed by the use of crossing light beams [3]. In this case the second quadrature processing channel is required to preserve all the information completely.…”