Tektronix TDSUSB2, Manual

Page: 42 / 250

Operating Basics
Table 5. Low and Full Speed measurements (cont.)
Area Option Description
Receiver Sensitivity Test Receiver Sensitivity Is an indicator of Receiver Sensitivity. A High Speed capable device must
indicate 'packet (Data) not received' (squelch) when the input of the
receiver falls below 100 mV differential amplitude. Similarly the device must
not indicate squelch if the differential amplitude is greater than 150 mV
Chirp Test Chirp Checks a part of handshake that occurs during Reset Protocol for high-
speed capable hubs and devices. In this handshake, the hub/host and the
device are required to detect chirp J and K of a specified minimum duration
and amplitude
Suspend Test Suspend Measures the time between the end of the last Start of Frame (SOF) and
the rising edge transition to the Full Speed J state. The acceptable range
should be between 3 ms to 3.125 ms. This is applicable if you have
selected a Host, Device, or a Hub-Upstream device
Resume Test Resume Resumes the High-speed operation in a device or a hub, which is indicated
by the presence of High-speed SOF packets (with 400 mV nominal
amplitude) following the K state driven by the host controller. For the Host
this is the time between the falling edge of D+ to the First SOF. This should
not exceed 3.0 ms
Rest from High-Speed
Test
Reset Measures the time between the beginning of the last SOF and before the
reset and the beginning of Chirp-K. This is between 3.1 ms and 6 ms. This
test will be applicable for Device and HUB upstream
Reset from Suspend Reset from Suspend Measures the time between the falling edge of D+ signal and the start of
Device chirp-K. This is between 2.5 us and 3 ms. This test is applicable for
Device and HUB upstream
Packet Parameter Packet Parameter Measures the parameter of the packet such as Sync Bits, EOP, and Inter-
Packet Gap depending on the selected measurement
Selecting a Measurement
To take a measurement, select Measurement from the Measurements menu,
which is also the default opening screen in the application. To access the Select
option in the Measurement menu, select Measurements> Select.
There are three categories of measurements: Low Speed, Full Speed, and High
Speed measurements. The measurements for Low, Full and High Speed signals
are Signal Quality Checks, Inrush Current Check, and Droop Test. The additional
measurements for High Speed tests are Receiver Sensitivity, Monotonic
Property, and Chirp Test, Packet Parameter, Suspend, Resume, Reset from
Suspend, and Reset from High Speed.
You need to select the measurements for a particular signal speed of the unit
under test. After selecting the tests, you must configure the application based on
Signal Source, Tier, Test Point, and Signal Direction.
You can test the units for the following:
Devices for Upstream Signal Quality Check
28 TDSUSB2 Universal Serial Bus Measurement Package