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Page 174 of 544 Transmission parameters
553-3011-100 Standard 14.00 January 2002
Longitudinal balance
Longitudinal balance defines the amount of impedance balance that exists
between the tip and ring conductor with respect to ground. Longitudinal
balance is measured by injecting a longitudinal signal on the tip and ring
conductors with respect to ground and measuring the amount of signal (noise)
that is introduced between the tip and ring. The equation for calculating
longitudinal balance is:
Longitudinal Balance = 20 Log Vs/Vm
Vs is the disturbing longitudinal voltage and Vm is the tip to ring metallic
noise voltage. Ideally the metallic noise voltage would be negligible and the
longitudinal balance would approach infinity.
Crosstalk
Crosstalk is speech signal (signalling) energy transferred from one voice
channel to another. The crosstalk coupling loss for every possible type of
connections over the frequency range of 200 to 3200 Hz is shown in Table 55.
Table 54
Longitudinal balance for loop start interfaces
Frequency
Hz
Minimum balance
dB
Average balance
dB
200 58 63
500 58 63
1000 58 63
3000 53 58