Teledyne LeCroy QPHY-ENET - Manual (Page 77)

QPHY-ENET Software Option
QPHY-ENET Operator’s Manual Rev G
77
Disturber Calibration Procedure
This procedure measures the amplitude of the disturbing sine wave being applied to the DUT. The calibration is
required to adjust the amplitude of the disturbing sine wave, which is generated by a dual-channel waveform
generator with 180-degree phase shift. See
X
Table 4. Gigabit Ethernet tests, modes and fixtures
X
for the various
signal frequency and amplitude settings used throughout the tests.
Note: All harmonics of the sine wave must be >40dB below fundamental. The TF-ENET-B embedded power splitter divides the signal
between the oscilloscope and the disturbing signal source.
1. Disconnect DUT from J68.
2. Connect waveform generator to J3 and J4.
3. Remove jumpers from J91 and J92, and install jumpers on J17, J19, J99, J100, J71 and J77.
4. Connect the oscilloscope channel 2 to J86, channel 3 to J87. The 50 Ω termination of the oscilloscope inputs
will terminate the signal pair with 100 Ω.
5. Set the waveform generator (AWG) to output the Mode 1 disturbing sine wave. The two output signals must
have the same amplitude but a 180 degree phase shift.
6. On Fixture Calibration dialog, press Measure (Disturber Amplitude) and adjust both AWG outputs until
reading is 1.4 V (Frequency is 31.25 MHz) for the Mode 1 test. Since the fixture splitter divides the value in
half, the entered value is half the standard voltage. Press Measure after each AWG adjustment.
7. Record the value of the AWG voltage setting for Mode 1 testing.
8. On the Fixture Calibration dialog, press Measure (Disturber Amplitude). Adjust both AWG outputs until
reading is 2.7 V for the Mode 4 test (Frequency is 20.833 MHz). Since the fixture splitter divides the value in
half, the entered value is half the standard voltage. Press Measure after each AWG adjustment.
9. Record the value of the AWG voltage setting for Mode 4 testing.
Figure 62. Disturbing Signal Amplitude measurement