{"id":165984,"date":"1992-11-01T00:00:00","date_gmt":"1992-11-01T00:00:00","guid":{"rendered":"https:\/\/www.microsoft.com\/en-us\/research\/msr-research-item\/a-tms320c25-based-telephone-scrambler-using-fast-computable-filter-banks\/"},"modified":"2018-10-16T20:04:19","modified_gmt":"2018-10-17T03:04:19","slug":"a-tms320c25-based-telephone-scrambler-using-fast-computable-filter-banks","status":"publish","type":"msr-research-item","link":"https:\/\/www.microsoft.com\/en-us\/research\/publication\/a-tms320c25-based-telephone-scrambler-using-fast-computable-filter-banks\/","title":{"rendered":"A TMS320C25-based telephone scrambler using fast-computable filter banks"},"content":{"rendered":"<div class=\"asset-content\">\n<p>In this work we describe the hardware architecture and the signal processing algorithm of a secure telephone which can be used over the public switched network. Using time-varying frequency-domain scrambling, a high level of security can be achieved, with no residual intelligibility. By means of the DFT filter banks implemented by the FFT and polyphase networks, all the signal processing for a full duplex conversation can be performed with a single TMS320C25 digital signal processor. The complete scrambler fits inside a standard telephone set unit.<\/p>\n<\/div>\n<p><!-- .asset-content --><\/p>\n","protected":false},"excerpt":{"rendered":"<p>In this work we describe the hardware architecture and the signal processing algorithm of a secure telephone which can be used over the public switched network. Using time-varying frequency-domain scrambling, a high level of security can be achieved, with no residual intelligibility. By means of the DFT filter banks implemented by the FFT and polyphase [&hellip;]<\/p>\n","protected":false},"featured_media":0,"template":"","meta":{"msr-url-field":"","msr-podcast-episode":"","msrModifiedDate":"","msrModifiedDateEnabled":false,"ep_exclude_from_search":false,"_classifai_error":"","msr-author-ordering":null,"msr_publishername":"Institute of Electrical and Electronics Engineers, Inc.","msr_publisher_other":"","msr_booktitle":"","msr_chapter":"","msr_edition":"International Conference on Signal Processing Applications and Technology","msr_editors":"","msr_how_published":"","msr_isbn":"","msr_issue":"","msr_journal":"","msr_number":"","msr_organization":"","msr_pages_string":"","msr_page_range_start":"","msr_page_range_end":"","msr_series":"","msr_volume":"","msr_copyright":"","msr_conference_name":"International Conference on Signal Processing Applications and Technology","msr_doi":"","msr_arxiv_id":"","msr_s2_paper_id":"","msr_mag_id":"","msr_pubmed_id":"","msr_other_authors":"Henrique S. 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