Split band processing for spread spectrum communications

• US 5,579,335 A
• Filed: 09/27/1995
• Issued: 11/26/1996
• Est. Priority Date: 09/27/1995
• Status: Expired due to Term

• Current Assignee: Echelon Corporation (Renesas Electronics Corporation)
• Original Assignee: Echelon Corporation (Renesas Electronics Corporation)
• Inventors: Sutterlin, Philip H., Stewart, J. Marcus
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Kim, Kevin
• Application Number:
  US08/534,574
• Time in Patent Office: 426 Days
• Field of Search: 375/343, 375/349, 375/350, 375/365, 375/367, 375/208, 375/200, 375/260, 375/240, 375/368
• US Class Current: 375/150
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 2203/5408 using protocols
• CPC Class Codes: H04B 2203/542 using zero crossing information
• CPC Class Codes: H04B 3/54 Systems for transmission via power distribution lines
• CPC Class Codes: H04L 25/03019 adaptive, i.e. capable of adjustment during data reception

Abstract

A method and apparatus for compensating for distortion in a spread spectrum communications system particularly useful where the spread spectrum is transmitted over a power line. The information carrying signal (ICS) is split into two sub-bands and the ICS in one sub-band (or a correlation value determined from the ICS in that sub-band) is delayed relative to the other sub-band. The ICS (or correlation values) from the two sub-bands are recombined after the delay and processed in an ordinary manner. The time delay is selected so as to compensate for the distortion. In one embodiment, the correlation peaks in each of the sub-bands are examined and the time delay is determined by, in effect, aligning the peaks in the two sub-bands in time so that when the two sub-bands are combined, a sharper correlation peak is obtained.

Claims

1. In a spread spectrum communication system where information is transmitted over a medium on an information carrying signal (ICS) having a broadband frequency spectrum, a method for compensation for distortion in the ICS, comprising the steps of:

separating the ICS into at least two sub-bands, each of the sub-bands covering a different predetermined band of frequencies, the frequencies bands of the sub-bands approximately covering the broadband frequency spectrum of the ICS;

separately correlating the ICS in each of the sub-bands with at least one predetermined pattern;

delaying results of one of the correlations with respect to results of the other correlation;

combining the results of the two correlations after the delaying step;

examining the results of the correlations; and

developing a control signal based on the examination of the results of the correlation, the control signal controlling the duration of the delaying.

2. The method defined by claim 1 wherein the delay is one of a plurality of discrete time delays.

3. The method defined by claim 1 wherein the ICS in each of the sub-bands is correlated with a different reference pattern.

4. In spread a spectrum communication system where information is transmitted over a medium on an information carrying signal (ICS) having a broad band frequency spectrum, a method for compensating for distortion in the ICS, comprising the steps of:

performing a first correlation between the ICS and a first predetermined pattern so as to obtain a correlation based on the lower frequencies contained in the ICS;

performing a second correlation between the ICS and a first predetermined pattern so as to obtain a correlation based on the higher frequencies contained in the ICS;

delaying the results of one of the first and second correlations with respect to the other correlation;

combining the results of the two correlations after the delaying step;

examining the results of the first and second correlations; and

developing a control signal based on the examination of the results of the first and second correlations, the control signal controlling the duration of the delaying.

5. In a spread spectrum communication system where information is transmitted over a medium on an information carrying signal (ICS) having a broadband frequency spectrum, a method for compensation for distortion in the ICS, comprising the steps of:

separating the ICS into at least two sub-bands, each of the sub-bands covering a different predetermined range of frequencies falling within the broadband frequency spectrum of the ICS;

delaying the ICS in one of the two sub-bands with respect to the ICS in the other sub-band;

combining the ICS in the two sub-bands after the delaying step; and

correlating the ICS after the combining step;

wherein the delaying comprises;

delaying one of the two sub-bands with respect to the other sub-band for a period of time where the period of time is selected to obtain a maximum correlation in the correlating step.

6. The method defined by claim 5 wherein the delay is one of a plurality of discrete time delays.

7. In a spread spectrum communication system where information is transmitted over a medium on an information carrying signal (ICS) having a broadband frequency spectrum, a method for compensation for distortion in the ICS, comprising the steps of:

separating the ICS into at least two sub-bands, each of the sub-bands covering a different predetermined band of frequencies, the frequencies bands of the sub-bands approximately covering the broadband frequency spectrum of the ICS;

separately correlating the ICS in each of the sub-bands with at least one predetermined pattern;

identifying at least one correlation peak in the results of the correlation for each of the sub-bands;

determining a time relationship between the correlation peaks in the sub-bands; and

delaying results of one of the correlations with respect to results of the other correlation for a period of time based on the time relationship between the peaks; and

,

combining the results of the two correlations after the delaying step.

8. The method defined by claim 7 wherein the determining of the time relationship comprises the determination of the time relationship between a correlation peak in a second of the sub-bands and a the plurality of correlation peaks n the first of the sub-bands closest in time occurring within a predetermined window to the correlation peak in the second of the sub-bands.

9. In a spread spectrum communication system where information is transmitted over a medium on an information carrying signal (ICS) having a broadband frequency spectrum, a method for compensation for distortion in the ICS, comprising the steps of:

separating the ICS into at least two sub-bands, each of the sub-bands covering a different predetermined band of frequencies, the frequencies bands of the subbands approximately covering the broadband frequency spectrum of the ICS;

separately correlating the ICS in each of the sub-bands with at least one predetermined pattern;

determining one or more parameters of the ICS;

establishing a delay based on the parameter;

delaying results of one of the correlation with respect to results of the other correlation for a period of time corresponding to the delay based on the parameter; and

,

combining the results of the two correlations after the delaying step.

10. In a spread spectrum communication system where information is transmitted over a medium on an information carrying signal (ICS) having a broad band frequency spectrum, a method for compensating for distortion in the ICS, comprising the steps of:

performing a first correlation between the ICS and a first predetermined pattern so as to obtain a correlation based on the lower frequencies contained in the ICS;

performing a second correlation between the ICS and a first predetermined pattern so as to obtain a correlation based on the higher frequencies contained in the ICS;

identifying at least one correlation peak in the results of each of the first and second correlations;

determining a time relationship between the correlation peaks in the first and the second correlations;

delaying the results of one of the first and second correlations with respect to the other correlation for a period of time based on the time relationship between the peaks; and

combining the results of the two correlations after the delaying step.

11. The method defined by claim 10 wherein the delay is one of a plurality of discrete time delays.

12. In a spread spectrum communication system where information is transmitted over a medium on an information carrying signal (ICS) having a broad band frequency spectrum, a method for compensating for distortion in the ICS, comprising the steps of:

performing a first correlation between the ICS and a first predetermined pattern so as to obtain a correlation based on the lower frequencies contained in the ICS;

performing a second correlation between the ICS and a first predetermined pattern so as to obtain a correlation based on the higher frequencies contained in the ICS;

determining one or more parameters of the ICS;

establishing a delay based on the parameter;

delaying the results of one of the first and second correlations with respect to the other correlation for a period of time corresponding to the delay based on the parameter;

combining the results of the two correlations after the delaying step;

examining the results of the first and second correlations; and

developing control signal based on the examination of the results of the first and second correlations, the control signal controlling the duration of the delaying.

13. The method defined by claim 12 wherein the delay is one of a plurality of discrete time delays.

14. In a spread spectrum communication system where information is transmitted over a medium on an information carrying signal (ICS) having a broadband frequency spectrum, a method for compensation for distortion in the ICS, comprising the steps of:

separating the ICS into at least two sub-bands, each of the sub-bands covering a different predetermined range of frequencies falling within the broadband frequency spectrum of the ICS;

measuring one or more parameters in the ICS;

establishing a delay based on the measured parameter;

delaying the ICS in one sub-band with respect to the ICS in the other sub-band for a period of time corresponding to the delay based on the parameter;

combining the ICS in the two sub-bands with respect to the ICS in the other sub-band; and

,

correlating the ICS after the combining step.