US 8,559,813 B2 · Passband reflectometer

Abstract

A time-domain (TD) reflectometer that is designed to operate based on probe and response signals that are substantially fully spectrally confined to a designated frequency passband. In one embodiment, the TD reflectometer uses a passband transmitter to generate the probe signal based on a pseudo-random bit sequence and a passband receiver to demodulate the response signal. The TD reflectometer determines the impulse response of a channel under test based on cross-correlation of the transmitter and receiver baseband signals. In various embodiments, the TD reflectometer can be designed to operate in an acoustic-frequency range, a radio-frequency range, or an optical-frequency range. Due to its passband configuration, the TD reflectometer is advantageously capable of determining impulse responses without disrupting the operation and/or interfering with normal functions of the tested channel.

Claims21

Dependent claims

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.

6 more elements

A method of characterizing an impulse response, the method comprising:

generating a drive signal based on a bit sequence using a passband transmitter;
converting the drive signal into a probe signal using an interface, 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;
applying the probe signal to a channel under test using the interface;
receiving a response signal corresponding to the probe signal back from said channel, wherein the interface is configured to receive said response signal;
generating a receiver-baseband signal based on the response signal using a passband receiver;
and
characterizing an impulse response of the channel based on the bit sequence and the receiver-baseband signal;
and
wherein the step of generating the drive signal using the passband transmitter comprises:
converting the bit sequence into a corresponding sequence of constellation symbols;
and
converting the sequence of constellation symbols into a transmitter-baseband signal, wherein:
the drive signal is generated based on the transmitter-baseband signal;
and
the impulse response is determined based on a correlation between the receiver-baseband signal and the transmitter-baseband signal.

12 more elements

Dependencies are inferred from the claim text.

Passband reflectometer

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Passband reflectometer

Life of this patent

Abstract

Claims21