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OneExpert DSL User's Guide
22052280, Rev. 015 April 2019
Chapter 13 Copper Testing
209
Far-End Crosstalk (FEXT) testing
The test detects coupling at the far end from one pair of wires to another. Using an
UltraFED IIB, a tone is transmitted from the far end on one pair of wires, and the ONX
measures crosstalk on another pair of wires at the near end. This allows coupling from one
pair to another to be detected.
1. Connect both Tip (A) and Ring (B) pairs (T/R and T1/R1 or A/B and A1/B1) to the lines
under test.
2. Connect the UltraFED IIB to the far end of the lines under test, such that Pair 1 on the
UltraFED is connected to T/R (A/B) and Pair 2 is connected to T1/R1 (A1/B1).
3. Select FEXT from the Mode menu.
4. Select the frequency to transmit. Use the left and right arrow keys to cycle though
commonly used frequencies or press the OK key to enter a custom frequency.
5. Press the Start key. The ONX will configure the UltraFED to transmit the selected
frequency and measure the crosstalk.
You have completed the test.
Return loss testing
This test measures return loss caused by impedance mismatches for a user-specified
frequency.
1. Connect the Tip and Ring (A and B) leads of the ONX to the line under test.
2. Connect the ground (E) lead of the ONX to ground.
3. Select
Mode , and then select Return Loss .
4. Select Options , and then select Single Frequency .
An UltraFED IIB may be used to terminate the far end of the line by selecting
Terminate with UFED from the Options menu.
5. To specify the range, press Technology , and then select:
• Wideband – 20 KHz – 10 MHz (ONX580P only)
• Narrowband – 200 Hz – 10 KHz (ONX580 only) ; 200 Hz – 20 KHz (ONX580P
only)
6. To specify the termination, press Technology , and then select:
• Wideband – 100 ohm, 120 ohm, 135 ohm
• Narrowband – 600 ohm, 900 ohm
7. Press Frequency and enter a value or use the arrows.
8. Press the Start softkey.
9. To save the results to a report, use the Tray menu.
The test is complete.