US 5,687,163 A · Method and apparatus for signal classification using I/Q quadrant histogram

Abstract

An efficient method and apparatus for determining, recording, and analyzing the phase history of a Line-in signal. The Line-in signal is coupled to a conventional demodulator. I and Q components are output by the conventional demodulator and coupled to an IQ quantizer. The IQ quantizer determines a quadrant on an I/Q plot from the amplitude of each component. A histogram is generated which indicates in which quadrant the Line-in signal was for a first sample, and in which quadrant the Line-in signal was for a second sample, the second sample having been taken immediately after the first sample. From this histogram, the number of times the Line-in signal transitions from one quadrant to another over a predetermined period of time is known. If the number of times the input signal crosses one of the axis of the I/Q plot in a first direction is greater than the number of times the input signal crosses that axis in the opposite direction, then the frequency of the Line-in signal differs from the frequency of the In-phase reference signal and the Quadrature reference signal. The frequency of the Line-in signal is directly related to the difference between the number of times the signal crosses an axis of the I/Q plot in a first direction, minus the number of time the signal crosses that axis of the I/Q plot in the opposite direction. The present invention also determines whether the Line-in signal represents a particular signaling pattern, such as the well-known AA pattern defined in the V.32 standard.

Claims28

Dependent claims

A signal classification system for analyzing characteristics of an input signal having associated phase transition indicators, each phase transition indicator indicating a relationship between the characteristics of the input signal during at least two points in time, including:

(a) a plurality of counters, each having count values, and each being associated with a unique phase transition indicator;
(b) a controller, coupled to the plurality of counters and configured to be coupled to an external device for:
(1) receiving phase transition indicators from the external device;
(2) incrementing each counter associated with each phase transition indicator received from the external device.

1 more element

A signal classification system for analyzing phase and frequency of an input signal having associated quadrature and in phase components, each component having an amplitude indicative of the relative phase of the input signal with respect to a reference signal, including:

(a) a plurality of counters, each having count values, and each counter being associated with a change in phase from one predetermined phase state to another predetermined phase state;
and
(b) a controller, configured to be coupled to an external device, and to the plurality of counters, for:
(1) receiving from the external device, indications of the amplitude of the quadrature component and the in-phase component of the input signal;
(2) determining, from the indications of the amplitudes of the quadrature and in-phase components, a series of consecutive phase states, each phase state associated with the amplitudes of one pair of quadrature and in-phase components at one point in time;
(3) incrementing the counter associated with a change in phase from a first phase state of a pair of two consecutive phase states from among the series of consecutive determined phase states to a second phase state of the pair.

3 more elements

A signal classification system for analyzing phase and frequency of an input signal having a quadrature component and an in-phase component, each component having an amplitude, including:

(a) a demodulator for receiving an input signal, a first reference signal, and a second reference signal, and for outputting a quadrature component and an in phase component indicative of the relative phase of the input signal with respect to each of the first and second reference signals;
(b) a plurality of counters, each having count values, and each counter being associated with a change in phase from one predetermined phase state to another predetermined phase state;
and
(c) a controller, configured to be coupled to the modulator and to the plurality of counters, for:
(1) receiving from the modulator the quadrature component and the in-phase component of the input signal;
(2) determining, from the quadrature and in-phase components, a series of consecutive phase states, each phase state associated with the amplitudes of one pair of quadrature and in-phase components at a point in time;
(3) incrementing the counter associated with a change in phase from a first phase state of a pair of two consecutive phase states from among the series of consecutive determined phase states to a second phase state of the pair.

4 more elements

A method for analyzing phase and frequency of an input signal having associated quadrature and in phase components, each component having an amplitude indicative of the relative phase of the input signal with respect to a reference signal, using a signal classification system having a plurality of counters, each having count values, and each counter being associated with a change in phase from one predetermined phase state to another predetermined phase state, the signal classification system also having a controller, configured to be coupled to an external device, and to the plurality of counters, including the steps of:

(a) receiving from the external device, indications of the amplitude of the quadrature component and the in-phase component of the input signal;
(b) determining, from the indications of the amplitudes of the quadrature and in-phase components, a series of consecutive phase states, each phase state associated with the amplitudes of one pair of quadrature and in-phase components at a point in time;
(c) incrementing the counter associated with a change in phase from a first phase state of a pair of two consecutive phase states from among the series of consecutive determined phase states to a second phase state of the pair.

Dependencies are inferred from the claim text.

Method and apparatus for signal classification using I/Q quadrant histogram

Life of this patent

Method and apparatus for signal classification using I/Q quadrant histogram

Life of this patent

Abstract

Claims28