Method for descrambling and symbol decoding

A test and measurement device, comprising:

• a first input coupled to a sideband data communication channel that carries data related to one or more high speed data channels between a host and a device, the first input structured to acquire data carried on the sideband data communication channel;
• a second input coupled to one of the one or more high speed data channels and structured to acquire data signals carried on the coupled high speed data channel;
• and
• one or more processors structured to:
• send a command to provoke the host to send a retiming message that includes one or more scrambling codes that were used to encode data signals on the coupled high speed data channel,
• extract the one or more scrambling codes from the retiming message,
• convert the data signals received on the coupled high speed data channel to coded data,
• descramble the coded data using the one or more scrambling codes extracted from the retiming message into descrambled data, and
• search the descrambled data for a predetermined code sequence.