Technical data

Link Layer Protocol Tests 17
Agilent U7232A DisplayPort Electrical Performance Compliance Test Application 147
Link Layer Protocol Tests
The link layer protocol tests consists of Pre- Emphasis, Level and Bit Rate
tests.
Link Layer Protocol - Pre-Emphasis
The link layer - pre- Emphasis test verifies if the pre- Emphasis of the DUT
can change accordingly from the lowest pre- Emphasis to the highest
pre- Emphasis setting.
The test must be made on the highest bit rate supported by the
differential voltage swings of 400 mV using a test pattern of PRBS 7. The
following equation is used to calculate the pre- Emphasis result:
Pre- Emphasis Result = 20log(VSwingPE/ VSwingNoPE)
VSwingPE = VHpe- VLpe
VSingNoPE = VHnope- VLnope
where:
VHpe = the high voltage value is measured using the histogram modes
at the top for transition eyes.
VLpe = the low voltage value is measured using the histogram modes at
the top for transition eyes.
VHnope = the high voltage value is measured using the histogram modes
at the top for non- transition eyes.
VLnope = the high voltage value is measured using the histogram modes
at the top for non- transition eyes.
Link Layer Protocol - Level
The link layer - level tests verifies if the amplitude level of the DUT can
change accordingly from the lowest to the highest setting.
The amplitude measurement is performed using the following equation at
all bit rates without pre- Emphasis and a PRBS 7 waveform:
Peak- to- peak Voltage = VH - VL where:
VH is the high voltage levelVL is the low voltage level
Link Layer Protocol - Bit Rate
The link layer - bit rate tests verifies if the bit rate of the DUT can change
accordingly from the lowest to the highest setting.