This document specifies the procedures which may be used to
\nensure that implementations of IS-733 compatible variable-rate
\nspeech codecs meet recommended minimum performance requirements.
\nThis speech codec is the Service Option 17 described in IS-733. The
\nService Option 17 speech codec is used to digitally encode the
\nspeech signal for transmission at a variable data rate of 266,
\n124,54 or 20 bits for each 20 ms frame.<\/p>\n
Unlike some speech coding standards, IS-733 does not specify a
\nbit-exact description of the speech coding system. The
\nspeech-coding algorithm is described in functional form, leaving
\nexact implementation details of the algorithm to the designer. It
\nis, therefore, not possible to test compatibility with the standard
\nby inputting certain test vectors to the speech codec and examining
\nthe output for exact replication of a reference vector. This
\ndocument describes a series of tests that may be used to test
\nconformance to the specification. These tests do not ensure that
\nthe codec operates satisfactorily under all possible input signals.
\nThe manufacturer shall ensure that its implementation operates in a
\nconsistent manner. These requirements test for minimum performance
\nlevels. The manufacturer should provide the highest performance
\npossible.<\/p>\n
Testing the codec is based on two classes of procedures:
\nobjective and subjective tests. Objective tests are based on actual
\nmeasurements of the speech codec function. Subjective tests are
\nbased on listening tests to judge overall speech quality. The
\npurpose of the testing is not only to ensure adequate performance
\nbetween one manufacturer's encoder and decoder but also that this
\nlevel of performance is maintained with operation between any
\npairing of manufacturers' encoders and decoders. This
\ninteroperability issue is a serious one. Any variation in
\nimplementing the exact standard shall be avoided if it cannot be
\nensured that minimum performance levels are met when
\ninter-operating with all other manufacturers' equipment meeting the
\nstandard. This standard provides a means for measuring performance
\nlevels while ensuring proper interoperation with other
\nmanufacturers' equipment.<\/p>\n
The issue of interoperability may only be definitively answered
\nby testing all combinations of encoderldecoder pairings. With the
\nnumber of equipment manufacturers expected to supply equipment,
\nthis becomes prohibitive task. The approach taken in this standard
\nis to define an objective test on both the speech decoder function
\nand the encoder rate determination function to ensure that its
\nimplementation closely follows that of the IS-733 specification.
\nThis approach is designed to reduce performance variation exhibited
\nby various implementations of the decoder and rate determination
\nfunctions. Because the complexity of the decoder is not large,
\nconstraining the performance closely is not onerous. If all
\nimplementations of the decoder function provide essentially similar
\nresults, then interoperation is more easily ensured with various
\nmanufacturers' encoder implementations.<\/p>\n
The objective and subjective tests rely upon the use of a master
\ncodec. This is a floating-point implementation of IS-733 written in
\nthe C programming language. The master codec is described more
\nfully in 3.4. This software is used as part of the interoperability
\ntesting.<\/p>\n
By convention in this document, the Courier font is used to
\nindicate C language and other software constructs, such as file and
\nvariable names.<\/p>\n","protected":false},"excerpt":{"rendered":"
Recommended Minimum Performance Standard for the High-Rate Speech Service Option 17 for Spread Spectrum Communication Systems<\/b><\/p>\n\n\n
\n Published By<\/td>\n Publication Date<\/td>\n Number of Pages<\/td>\n<\/tr>\n \n TIA<\/b><\/a><\/td>\n 2000<\/td>\n NA<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"featured_media":0,"template":"","meta":{"rank_math_lock_modified_date":false,"ep_exclude_from_search":false},"product_cat":[2646],"product_tag":[],"class_list":{"0":"post-692503","1":"product","2":"type-product","3":"status-publish","5":"product_cat-tia","7":"first","8":"instock","9":"sold-individually","10":"shipping-taxable","11":"purchasable","12":"product-type-simple"},"_links":{"self":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product\/692503","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/types\/product"}],"wp:attachment":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media?parent=692503"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_cat?post=692503"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_tag?post=692503"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}