Technical data

74 DSOX4USBSQ USB 2.0 Signal Quality Analysis Application Electrical Testing Notes
5 Hub Downstream Signal Quality Testing
The analyzed acquisition remains on screen and can be viewed by
moving or dismissing the results dialog box.
You can run tests when the oscilloscope is already stopped. This is
useful in the case of embedded hosts (and other cases) where the
device under test (DUT) may not easily be placed in a test mode, and
you want to analyze already acquired data.
See Also • Chapter 6, “Saving Test Results to an HTML File,” starting on page 81
Hub Downstream Full Speed Connection
Perform these connection steps:
1 Attach the passive probes to the oscilloscope's Channel 3 and Channel 2
inputs.
2 Attach the SQiDD board to the hub under test.
3 Attach the upstream port of the hub under test to the end of 4
self- powered hubs and a host system. Hub #1 has to be a full- speed
hub and hub #2 a Hi-speed hub. The other hubs can be either full
speed or hi- speed hubs.
4 Attach a full speed device to the same section of the SQiDD board. If
the section has a switch, it should be set to ON.
5 Connect the oscilloscope Channel 2 probe to D+ probe point of the
device under test portion. Connect the oscilloscope channel Channel 3
probe to the D- probe point of the device under test portion.
6 Exit the HS Electrical Test Tool if you have previously launched it.
NOTE
Placing a full speed and/or a high-speed device downstream of a full speed hub forces both
to operate in full speed mode.