Nortel Meridian 1 Option 11C Compact, Technical Reference Manual, Page: 31 / 148

Page 20 of 136 Chapter 2 — Transmission parameters
553-3121-100 Standard 2.0 September 1998
Return Loss
The return loss measures how closely the input impedance matches the
required impedance (source impedance). Return loss at an impedance
discontinuity in a transmission path is the ratio (in dB) of the power level of
an incident signal to the power level of the resulting reflected signal.
Echo Return Loss (ERL) is a weighted average of the return loss value over
the frequency range of 500 to 2500 Hz.
Single Frequency Return Loss (SFRL) is the lowest value of return loss in the
frequency range of 200 to 3200 Hz.
The return loss is measured against its characteristic input impedance (see
Table 7).
Reference Source is 0 dBmO.
Table 7
Return Loss
Interface Echo Return Loss (dB)
Single Frequency
Return Loss (dB)
2 Wire Line >18 >12
2 Wire Trunk >22 >17