What is the difference between physical and phy layer conformance testing?
The terms physical and phy layer refer to specific clauses of the SAS standard. Physical layer conformance tests are based on Clause 5 of the SAS spec, and cover measurements typically related to the electrical characteristics of the device’s transmitter and transmitted signaling. This includes jitter, rise/fall time, amplitude, and return loss/impedance characteristics. Phy layer conformance tests are based on Clause 6 of the SAS spec, and deal more with the coding level and state machine aspects of a SAS device. Error injection and handling, timing issues, and 8B/10B coding issues are covered by the phy layer tests.
