Agilent Technologies DSOX4USBSQ USB 2.0 Manual de Serviço descarregar pdf (Página 8)

8 DSOX4USBSQ USB 2.0 Signal Quality Analysis Application Electrical Testing Notes

1 Preparing for Signal Quality Analysis

Oscilloscope Requirements

The DSOX4USBSQ USB 2.0 Signal Quality Analysis application requires an

Agilent InfiniiVision 4000 X-Series oscilloscope, firmware version 3.10 or

later.

For Hi-Speed

Tests

Hi- Speed tests require a 1.5 GHz bandwidth model oscilloscope.

Hi- Speed tests on a 2- channel oscilloscope with single- ended SMA cable

connections is not supported because the sample rate will not meet the

5 GSa/s rate that is required. Using a differential probe on a 2- channel

oscilloscope works fine.

For Full and Low

Speed Tests

Full and Low Speed tests can be performed with 200 MHz, 350 MHz,

500 MHz, 1 GHz, or 1.5 GHz bandwidth model oscilloscopes.

Full Speed testing is best on a 4- channel oscilloscope because when using

a 2- channel oscilloscope, channels 1 and 2 are non- interleaved and the

sample rate will be below the 4 GSa/s that the USB-IF testing procedures

require. If Full Speed tests are run on a 2- channel oscilloscope,

interpolation is used on the data.

For Optional USB

2.0 Triggering and

Decode in the

Oscilloscope

The optional DSOX4USBH and DSOX4USBFL products (for USB 2.0

Hi- Speed and Full/Low- Speed triggering and decode, respectively) can be

very useful tools for identifying and triggering on packets that you might

want to run the USB signal quality tests on.

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Agilent Technologies DSOX4USBSQ USB 2.0 Manual de Serviço Página 8