Teledyne LeCroy QPHY-SATA - Manual (Page 27)

QPHY-SATA Software Option
915745 Rev G
27
Physical Layer General Requirements (PHY)
The PHY group of tests includes parameters from Table 29 – General Specifications in the SATA specification
Rev 3.0. There are four tests in this group. The High Frequency Test Pattern (HFTP) is used for all four PHY
tests. The data is demodulated and a low-pass filter is then applied to create an SSCTrack which displays how
the data rate varies over time. The carrier frequency of the SSC Track is set to the nominal frequency if there is
no SSC. If SSC is enabled the carrier is set to the center frequency of the SSC waveform, assuming max
deviation. The SSC Track has a low pass filter (LPF) with a cutoff frequency of 1.98 MHz. The output of the SSC
Track is multiplied by 2 and offset by the mean frequency so that it becomes a track of the bitrate centered at the
mean frequency.
PHY-01 – Unit Interval
This test measures the mean unit interval. It is measured by taking the mean of the SSC Track. This test applies
whether SSC is enabled or not. The minimum and maximum unit intervals are also reported.
PHY-02 – Frequency Long Term Accuracy
This test measures “ftol”, the deviation of the mean data rate from the nominal data rate. It is calculated as:
(mean data rate
– nominal data rate) / nominal data rate * 1 million ppm
This test only applies to products that do not have SSC enabled.
PHY-03 – Spread Spectrum Modulation Frequency
This test measures the frequency of the spread spectrum modulation. It only applies to products that have SSC
enabled.
PHY-04 – SSC Modulation Deviation
This test measures the deviation of the data rate from the nominal data rate. This test only applies to products that
have SSC enabled. It is calculated as follows:
(mean of maximum data rate – nominal data rate) / nominal data rate * 1 million ppm
(mean of minimum data rate – nominal data rate) / nominal data rate * 1 million ppm