Final answer:
Equal level far end cross talk (ELFEXT) is a measure of interference between twisted pair cables. Power sum equal level far end cross talk (PS-ELFEXT) includes the combined effect of multiple disturbers. PS-ELFEXT is obtained by summing the disturbance caused by all close pairs.
Step-by-step explanation:
The concept of equal level far end cross talk (ELFEXT) is a measure of the amount of interference or crosstalk between two pairs of twisted pair cables. It represents the unwanted signal that is induced in a receiving cable conductor due to coupling with a transmitting cable conductor. ELFEXT is usually expressed in decibels (dB) and indicates the difference between the signal level on the disturbed cable (far end) and the signal level on the transmitter cable (near end).
The relationship between equal level far end cross talk (ELFEXT) and power sum equal level far end cross talk (PS-ELFEXT) is that PS-ELFEXT takes into account the combined effect of multiple disturbers on one cable, whereas ELFEXT does not. PS-ELFEXT is obtained by summing the disturbance caused by all close pairs in the same cable.