4RF Aprisa XE, User Manual

Page: 98 / 272

Configuring the traffic interfaces | 97
7. Select the DFXS Line Impedance
This option sets the DFXS line termination impedance and the hybrid balance impedance to the
same value.
Selection Description
600 Ω Standard equipment impedance Default
600 Ω  + 2.16 uF Standard equipment impedance with low frequency
roll-off
900 Ω Typically used on loaded cable pairs
900 Ω  + 2.16 uF Typically used on loaded cable pairs with low
frequency roll-off
TN12 Standard complex impedance for Australia
TBR21 Widely deployed complex impedance
BT3 Standard complex impedance for New Zealand
ƒ On a short line (< 100 meters), the selected impedance should match the impedance of the
phone (off-hook).
ƒ On a long line (> 1000 meters), the selected impedance should match the impedance of the
phone (off-hook) as seen through the line.
If you are not sure what the expected impedance value should be, check with the CPE equipment
supplier.
8. Set the DFXS Transhybrid Balance (usually not required to change).
The default Transhybrid Balance value (0 dB), provides the best circuit performance where the
balance impedance (set by the Line Impedance setting) matches the impedance of the line.
You should only adjust the transhybrid balance when the balance impedance does not match the
actual line impedance. You can achieve small circuit improvements using this option.
9.
Set the DFXS Ringer Frequency.
This option sets the DFXS Ringing Frequency.
Selection Description
17 Hz Used in older networks
25 Hz Standard ringing frequency Default
50 Hz Used by some telephone exchanges