Multiplicative mismatched filters for optimum range sidelobe suppression in Barker code reception

• US 20080111734A1
• Filed: 11/14/2006
• Published: 05/15/2008
• Est. Priority Date: 11/14/2006
• Status: Active Grant

• Current Assignee: Adly T. Fam, Indranil Sarkar
• Original Assignee: Adly T. Fam, Indranil Sarkar
• Inventors: Fam, Adly T., Sarkar, Indranil
• Granted Patent: US 7,492,312 B2
• Time in Patent Office: Days
• US Class Current: 342/195
• CPC Class Codes: G01S 13/284 using coded pulses
• CPC Class Codes: H03H 17/0219 Compensation of undesirable effects, e.g. quantisation noise, overflow stability problems H03H17/0461
• CPC Class Codes: H03H 17/0236 using codes
• CPC Class Codes: H03H 17/0248 Filters characterised by a particular frequency response or filtering method
• CPC Class Codes: H03H 17/06 Non-recursive filters
• CPC Class Codes: H04B 1/7093 Matched filter type

Abstract

Very efficient sidelobe suppression of Barker codes is achieved through the use of a mismatched filter, which is comprised of a conventional matched filter cascaded with a computationally efficient filter based on multiplicative expansion. Several constant parameters are introduced in the terms of the expansion and are optimized to improve the performance of the filter. Optimized mismatched filters for length 13, 11, 7 and 5 Barker codes are presented. For each of these codes, filters with one, two and three stages are studied. The technique is extended to compound Barker codes based on their representation in a factored form in the z-domain. Hardware requirements for the filters discussed in the disclosure are also presented.

Claims

1. A mismatched filter for systems that employ Barker codes as pulse compression codes, the said filter being a sidelobe suppression filter in cascade with a matched filter matched to the code of interest;

the sidelobe suppression filter being based on a multiplicative expansion, approximation and parameterization of the transfer function of the inverse filter 1/R(z) where R(z) denotes the matched filter output in the z-domain. The parameters introduced in the said mismatched filter transfer function are optimized for the particular Barker code and the number of terms used in the multiplicative expansion.

2. The method and filtering technique as described in claim 1, when extended to compound Barker codes as a cascade of mismatched filters, with appropriate zero paddings as needed, for the individual codes used to construct the compound codes.

3. The method and filtering technique as described in claim 1, when any minimum peak sidelobe (MPS) code is used as the pulse compression code.