Persons with hearing impairments or speech impediments are able
\nto communicate over the telephone using TTY\/TDD (teletype\/text
\ntelephone devices for the deaf), hereafter referred to as TTY
\ndevices. These devices typically have a keyboard and a 2-line
\ndisplay, allowing a TTY user to type messages over the phone lines
\nto another TTY user. TTY devices transmit the characters at either
\n45.45 bps or 50 bps using the Baudot code, a binary frequency shift
\nkeyed scheme that is carrierless, half duplex, and without error
\nprotection.<\/p>\n
In June 1996, the FCC adopted Section 20.18(c) of the
\nCommission's Rules. It requires that, as of October 1, 1997, all
\ncovered wireless carriers must be capable of transmitting 911 calls
\nfrom individuals with speech or hearing disabilities through means
\nother than mobile radio handsets, e.g., through the use of TTY
\ndevices. The pre-existing digital wireless networks have rendered
\nTTY conversations unintelligible. The frame and bit errors that
\noccur over the air, as well as the variable rate speech coding,
\nconspired to create unacceptably high character error rates.<\/p>\n
The purpose of this standard is to establish minimum performance
\nrequirements and a test procedure for verifying solutions for
\ntransporting the Baudot code over cdma2000 [7] wireless networks
\nusing 3GPP2 13K Vocoder [2], EVRC [1], SMV [8], EVRC-B, EVRC-WB,
\nand EVRC-NW [1], corresponding to Service Options 17, 3, 56, 68,
\n70, and 73, respectively. An electronic package containing tools
\nand test vectors for the purpose of performing these minimum
\nperformance tests accompanies this standard.<\/p>\n
For the remainder of this document, the term test vocoder refers
\nto the speech coder with TTY extension for which compliance with
\nthis document is being verified. The term reference vocoder refers
\nto the C simulation of the vocoder with the most recent TTY
\nextension, which is provided in the accompanying electronic
\npackage.<\/p>\n","protected":false},"excerpt":{"rendered":"
TTY\/TDD Minimum Performance Specification<\/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 2012<\/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-691959","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\/691959","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=691959"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_cat?post=691959"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_tag?post=691959"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}