Method and apparatus for detecting and quantifying impairments in QAM signals
First Claim
1. A method for detecting and quantifying impairments of a received communication signal of a quadrature amplitude modulation (OAM) data communication system represented by a plurality of ideal values, said method comprising the steps of:
- a) storing a statistically significant number of a plurality of received points of said signal for each of said ideal values corresponding to a plurality of groups of said plurality of ideal values, wherein said plurality of ideal values being distributed around an origin of said coordinate system in a plurality of adjacent rows and columns forming a square shape pattern, said rows and columns being in a direction of said in-phase axis and said quadrature axis respectively, said pattern defining four outer corner ideal values, external horizontal and vertical ideal values of said two outermost of said rows and two outermost of said columns respectively, internal ideal values in a center proximity of said origin, different combinations of said received points corresponding to respective of said defined ideal values forming said plurality of groups, each of said received points being defined by an in-phase and a qadrature components in a coordinate system in which a first axis is an in-phase axis and a second axis is a quadruture axis, said components having corresponding ideal components from their respective of said ideal values, each of said groups corresponding to a respective of said imparments and being specific to the same wherein said impairments are selected from a group including signal compression ratio. I/O gain imbalance ratio, I/O phase imbalance, phase noise, signal to noise ratio, signal to interference ratio and clipping level;
b) analyzing said components of said received points of respective of said groups in relation with their respective of said ideal components of said ideal values to quantify said impairments of said signal and provide calculated values of the same;
c) displaying said calculated values of said impairments.
5 Assignments
0 Petitions
Accused Products
Abstract
A method for detecting and quantifying impairments of a received communication signal of a QAM data communication system represented by a plurality of ideal values. The method includes storing a statistically significant number of a plurality of received points of the signal for each ideal value corresponding to a plurality of groups of said plurality of ideal values. The received points are defined by an in-phase and a quadrature components in a coordinate system in which a first axis is the in-phase axis and a second axis is a quadrature axis. The components have corresponding ideal components from their respective ideal value. Each group corresponds to respective impairments and is specific to the same.
-
Citations
14 Claims
-
1. A method for detecting and quantifying impairments of a received communication signal of a quadrature amplitude modulation (OAM) data communication system represented by a plurality of ideal values, said method comprising the steps of:
-
a) storing a statistically significant number of a plurality of received points of said signal for each of said ideal values corresponding to a plurality of groups of said plurality of ideal values, wherein said plurality of ideal values being distributed around an origin of said coordinate system in a plurality of adjacent rows and columns forming a square shape pattern, said rows and columns being in a direction of said in-phase axis and said quadrature axis respectively, said pattern defining four outer corner ideal values, external horizontal and vertical ideal values of said two outermost of said rows and two outermost of said columns respectively, internal ideal values in a center proximity of said origin, different combinations of said received points corresponding to respective of said defined ideal values forming said plurality of groups, each of said received points being defined by an in-phase and a qadrature components in a coordinate system in which a first axis is an in-phase axis and a second axis is a quadruture axis, said components having corresponding ideal components from their respective of said ideal values, each of said groups corresponding to a respective of said imparments and being specific to the same wherein said impairments are selected from a group including signal compression ratio. I/O gain imbalance ratio, I/O phase imbalance, phase noise, signal to noise ratio, signal to interference ratio and clipping level; b) analyzing said components of said received points of respective of said groups in relation with their respective of said ideal components of said ideal values to quantify said impairments of said signal and provide calculated values of the same; c) displaying said calculated values of said impairments. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. A method for detecting and quantifying parameters of a received communication signal of a quadrature amplitude modulation data communication system represented by a specific coding, said signal parameters are selected from a group including real baud rate, real carrier frequency, amplitude and group delay response, and low frequency disturbance (hum) said method comprising the steps of:
-
a) storing a statistically significant number of a plurality of operating parameters available and extracted from a signal demodulator of a receiver of said signal; b) analyzing said plurality of operating parameters to quantify said signal parameters of said signal and provide calculated values of the same further comprising; b1) counting a MPEG (Motion Picture Expert Group) stream word rare over a specific time duration of an order of magnitude of one second from said plurality of operating parameters; b2) determining a signal user bit rate and consequently said real baud rate parameter of said signal using said MPEG word rate and said specific coding, said real baud rate impairment being accurate within an accuracy of a counter time base of said demodulator; wherein said operating parameters include a control word and a control word dimensional factor, said method further comprising, the steps of; b3) performing a re-sampling of said operating parameters to recover an actual baud rate of said signal; b4) determining said real carrier frequency parameter of said signal from said actual baud rate using a numerically controlled frequency generator having an output frequency being related to said actual baud rate by multiplying the latter (actual baud rate) by an average of said control word and dividing by said control word dimensional factor; and wherein said signal being filtered by an equalizer of said receiver of said data communication system to compensate for linear distortions of said signal using complex coefficients, said distortions being frequency responses, phase responses and reflections, said operating parameters further include said complex coefficients from said equalizer, said method further comprising the step of; b5) determining said amplitude and group delay response parameter of said signal by calculating an amplitude and a phase from said frequency responses and a group delay from said phase responses of said equalizer respectively using said complex coefficients, wherein said signal being related to a power line, said method further comprising the steps of; b6) synchronizing a spectrum analyzer to said power line having a frequency and first harmonics being order of magnitude less than a frequency of said signal; b7) sampling sequences of an amplitude of said signal with a resolution bandwidth of a same order of magnitude as said signal using a typical functionality of said spectrum analyzer; b8) triggering said sequences to said frequency and first harmonics of said power line and averaging the same; b9) determining said low frequency disturbance (hum) parameter of said signal by zooming on small amplitude modulation of said averaging to extract a peak-re-peak modulation; and c) integrally displaying said calculated values of said signal parameters. - View Dependent Claims (13, 14)
-
Specification