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TIA-718

Revision E, December 1, 2013

Complete Document

Minimum Performance Specification for the Enhanced Variable Rate Codec, Speech Service Options 3, 68, 70, 73 and 77 for Wideband Spread Spectrum Digital Systems

Includes all amendments and changes through Addendum 1, December 2013


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Referenced Items:

ANSI S1.4
ANSI X3.159
IEEE 269
IEEE 661

Product Details:

  • Revision: Revision E, December 1, 2013
  • Published Date: December 2013
  • Status: Active, Most Current
  • Document Language: English
  • Published By: Telecommunications Industry Association (TIA)
  • Page Count: 222
  • ANSI Approved: No
  • DoD Adopted: No

Description / Abstract:

This document specifies the procedures to test implementations of EVRC-A, EVRC-B, EVRC-WB, EVRC-NW or EVRC-NW2K compatible variable-rate speech codecs either by meeting the bit-exact  implementation, or meeting recommended minimum performance requirements. The EVRC-A is the Service Option 3 (SO 3) speech codec, the EVRC-B is the Service Option 68 (SO 68) speech codec, the EVRC-WB is the Service Option 70 (SO 70) speech codec, the EVRC-NW is the Service Option 73 (SO 73) speech codec, and the EVRC-NW2K is the Service Option 77 (SO 77) speech codec all described in [1]. The procedures specified in this document for the SO 3 speech codec are fully consistent with those contained in [3]. The SO 3 speech codec is used to digitally encode the speech signal for transmission at a variable data rate of 8550 bps, 4000 bps, or 800 bps. The SO 68 speech codec is used to digitally encode the speech signal for transmission at a variable data rate of 8550 bps, 4000 bps, 2000 bps, or 800 bps. The SO 70 speech codec is used to digitally encode the speech signal for transmission at a variable data rate of 8550 bps, 4000 bps, or 800 bps. The SO 73 speech codec is used to digitally encode the speech signal for transmission at a variable data rate of 8550 bps, 4000 bps, 2000 bps, or 800 bps. The SO 77 is same as SO 73 except it includes a maximum  rate 2 kbps mode speech codec.

Like some other speech coding standards, this standard provides a bit-exact method of verifying the test codec for minimum performance. In this optional procedure, a given set of test vectors are input to the test codec and the output vectors from the test codec must be bit-exact with the output vectors given in the software distribution which is associated with this standard. If they are bit-exact, the test codec passes the minimum performance requirement and no further testing is required. The bit-exact mode of testing, however, is only applicable to codecs whose design conforms in all respects to the algorithmic description of the specific EVRC service option, including the noise suppression, rate determination and post-filter components.

Should the candidate EVRC differ in any of these components, the test codec shall be tested using the objective and subjective tests prescribed by this standard. That is, EVRC-compliance of a "test codec" can be achieved by either:

• Complying with Sections 2.1.1 and 2.1.2 (SO 3), or Sections 2.2.1 and 2.2.2 (SO 68), or Sections 2.3.1 and 2.3.2 (SO 70), or Section 2.4.1 and 2.4.2 (SO 73), or Section 2.5.1 and 2.5.2 (SO 77) and demonstrating bit-exactness according to the procedure described in Section 3.1.4 (SO 3), or Section 3.2.4 (SO 68), or Section 3.3.4 (SO 70), or Section 3.4.4 (SO 73), or Section 3.5.4 (SO 77) respectively.

• Following the objective and subjective testing procedures set forth in Sections 2.1.1 and 38 2.1.2, or Sections 2.2.1 and 2.2.2, or Sections 2.3.1 and 2.3.2, or Section 2.4.1 and 2.4.2 3 (SO 73), or Section 2.5.1 and 2.5.2 (SO 77) of this standard.