Patent ID: 6937717

Claim:
A detector for detecting a signal at a signaling frequency on a transmission line carrying a communication signal comprising signaling frequencies and noise, said detector comprising: a resonator having an input configured for coupling to the transmission line to receive the communication signal, an output for outputting a resonated signal, and a control used to configure said resonator; a controller coupled to said control of said resonator for configuring said resonator in a first state corresponding to the signaling frequency and in a second state corresponding to a reference frequency; a comparator coupled to the output of said resonator for comparing a first value of said resonated signal at the output of said resonator configured in said first state to a second value of said resonated signal at the output of said resonator configured in said second state, said comparator generating an indicator based on the comparison; a running maximum circuit coupled between said resonator and said comparator for determining a first largest value of said resonated signal at said output of said resonator configured in said first state during a measurement period, said first largest value being said first value, and determining a second largest value of said resonated signal at said output of said resonator configured in said second state during another measurement period, said second largest value being said second value; and a counter coupled to said running maximum circuit and said controller for determining said measurement periods.