ITU-T G.164

Abstract

<em>Application</em> <br>This Recommendation is applicable to the design of echo suppressors used on international telephone connections which have: <br>mean one-way propagation times between subscribers of up to the maximum regarded as acceptable in Recommendation G.114. (The design of the echo suppressor should not impose any lower limit of delay on its use); <br>a level of circuit noise entering the send-in port (<em>S</em>_in) or receive-in port (<em>R</em>_in) of up to -40 dBm0p; <br>round trip end delays between the receive-out port (<em>R</em>_out) and <em>S</em>_in port of the echo suppressor of up to 24 ms (including all transmission and switching plant). <br><em>Note</em> - Recommendation G.161 [1] refers to 25 ms. The value of 24 ms, a multiple of 2, is used in this Recommendation as being more applicable to the design of digital echo suppressors; <br>a loss of the echo path in dB (see the Recommendation cited in [2] that is likely to be such that the minimum loss from <em>R</em>_out to <em>S</em>_in of the echo suppressor will be equal to the difference between relative levels at, these two ports plus 6 dB. <br>Echo suppressors must be designed to perform in a satisfactory manner under all the conditions described above.