50
DSOX4USBSQ USB 2.0 Signal Quality Analysis Application Electrical Testing Notes
3
Host Signal Quality Testing
Host Low Speed Signal Quality Test
To set up and run the Host Low Speed signal quality tests:
1
Connect the USB Device, test fixtures, and equipment. See
"Host Low
Speed Connection"
on page 52.
2
Set up the test signal/packet that will be analyzed.
To generate bus traffic, connect a known good Low Speed device to the
port under test and capture a Low Speed packet to perform the eye
pattern analysis.
3
On the oscilloscope's front panel, press the
[Analyze]
key.
4
In the Analyze Menu, press the
Features
softkey; then, select
USB Signal
Quality
.
5
Press the
Test
softkey and select the
Host Low Speed Signal Quality
test.
6
Press the
Signals
softkey. In the USB Signal Quality Signals Menu:
a
Press the
D+ Source
softkey and select the analog input source
channel connected to the D+ signal (channel 2 in the previous
connection instructions).
b
Press the
D- Source
softkey and select the analog input source
channel connected to the D- signal (channel 3 in the previous
connection instructions).
On 4- channel oscilloscopes, you are forced to use different channel
pairs for the D+ and D- signals. This provides the maximum sample
rate. (Channels 1 and 2 are one pair and channels 3 and 4 are the
other pair.)
7
Press the
Auto Setup
softkey to automatically set up the oscilloscope for
the selected test.
Table 8
Equipment Used in Host Downstream Low Speed Signal Quality Test
Quantity
Item
Description/Model
1
Oscilloscope
Agilent 4000 X-Series
2
Passive probes
Probes included with the oscilloscope are
sufficient.
1
Host test bed computer
Any computer with the Windows XP,
Windows 7, or Windows 8 operating system
and hi-speed USB ports.
1
SQiDD board
Agilent E2646A/B
1
low speed USB device
Any USB mouse
