Maintenance Architecture
555-233-143
1-22 Issue 1 May 2002
ERL and SFRL Talking State
Echo-Return Loss (ERL) and Single-Frequency Return Loss (SFRL) performance
are usually dominated by termination and/or loop input impedances. The system
provides an acceptable level of echo performance if the ERL and SFRL are met,
as follows:.
Peak Noise Level
■ Analog to analog — 20 dBrnC (decibels above reference noise with
C-filter)
■ Analog to digital — 19 dBrnC
■ Digital to analog — 13 dBrnC
Echo Path Delay
■ Analog port to analog port — < 3 ms
■ Digital interface port to digital interface port — < 2 ms
Station-to-station ERL should meet or exceed 18 dB SFRL
should meet or exceed 12 dB
Station to 4-wire trunk connection ERL should meet or exceed 24 dB SFRL
should meet or exceed 14 dB
Station to 2-wire trunk connection ERL should meet or exceed 18 dB SFRL
should meet or exceed 12 dB
4-wire to 4-wire trunk connection ERL should meet or exceed 27 dB SFRL
should meet or exceed 20 dB
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