Patent ID: 8705596

Claim:
A method in a physical layer device, comprising: receiving, by said physical layer device, a first instance of an input signal pattern; determining, by said physical layer device, a first response of a clock recovery circuitry circuit in said physical layer device to said first instance of said input signal pattern; receiving, by said physical layer device, a second instance of said input signal pattern; determining, by said physical layer device, a second response of said clock recovery circuitry circuit to said second instance of said input signal pattern; comparing, by said physical layer device, said determined first response to said determined second response, wherein said comparing comprises comparing responses of a capacitor control element in a phase locked loop in said clock recovery circuit; and generating, by said physical layer device, a result signal indicative of an error condition if said comparison of said determined first response to said determined second response indicates a variation beyond an acceptable threshold amount.