Teledyne LeCroy QPHY-USB - Manual (Page 59)

QPHY-USB Software Option
QPHY-USB Operator’s Manual Rev F
59
Hub Full-Speed Downstream Signal Quality
1. Set up the equipment as follows. The hub is tested at tier 5 (at the end of a chain of 4 hubs) connected to
a device at tier 6. The first hub in the chain should be a USB Full-Speed hub. The chain of hubs is
intended to test the receiver sensitivity of the hub.
Figure 61. Hub Full-Speed Downstream Signal Quality Setup
1. Start the USB High-Speed Electrical Test Tool, select Device, and then press Test.
2. Press Enumerate Bus and verify the hub under test appears in the Select Device window.
3. A Full-Speed device is connected to the downstream port of the hub under test through the SQ Device
section of the Test Fixture.
4. Select Hub in the mode control and FS Downstream Signal Quality in the test control of the USB Test
Wizard.
5. Press the Single Trigger front panel button on the oscilloscope until a full packet is captured on the
screen. Use the cursors to select the downstream portion of the data packet (as the following figure
shows). The cursors are set to 1 UI before the first bit in the sync field on the left and 1 UI after the end of
the EOP on the right.
6. Press Next in the USB Test Wizard to process the waveform. MATLAB generates an eye pattern
waveform file and an HTML signal quality report. These files are stored in the
D:\Applications\USB2\Results directory.