Patent ID: 8559813

Claim:
An apparatus comprising: a passband transmitter configured to generate a drive signal based on a bit sequence; an interface configured to convert the drive signal into a probe signal, apply the probe signal to a channel under test, and receive a response signal corresponding to the probe signal back from said channel; a passband receiver configured to receive, from the interface, an input signal corresponding to the response signal and to convert said input signal into a receiver-baseband signal; and a high-pass filter coupled between the interface and the passband receiver, wherein: the probe signal is spectrally limited to a spectral band located at frequencies higher than a first threshold frequency, wherein the first threshold frequency is a nonzero frequency; the apparatus is configured to characterize an impulse response of the channel under test based on the bit sequence and the receiver-baseband signal; and the high-pass filter has a cut-off frequency that is lower than or about the same as the first threshold frequency.