US5008903A
Expired / Lapsed
US
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Adaptive transmit pre-emphasis for digital modem computed from noise spectrum
Assignee: REMBRANDT TECHNOLOGIES LP
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Filing: 1989-05-25
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Granted: 1991-04-16
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Expires: 2009-05-25
Abstract
Abstract An apparatus and method calculates pre-emphasis coefficients for a transmitting modem based upon the noise spectrum as it is received at the receiving modem. A noise spectrum analysis circuit calculates a difference between the best-fit transmitted data and the actually received data. This difference is used to compute a discrete Fourier transform of the noise spectrum, which is transmitted back to the transmitting modem on the secondary channel. This data is used to calculate filter coefficients for the transmitting modem.
Inventors
- 👤 William L. Betts
- 👤 James J. DesRosiers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:02
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/0002
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
98 words
An apparatus for calculating pre-emphasis coefficients for a transmitting modem in a communications system, including: first transmitting means in the transmitting modem, including adjusting means responsive to the pre-emphasis coefficients for adjusting frequency-dependent characteristics of an output of said first transmitting means; receiving means for receiving said output from said first transmitting means; generating means for generating parameters responsive to a noise spectrum of said output including means for calculating said noise spectrum of said output; second transmitting means for transmitting said parameters to the transmitting modem, and computing means for computing the pre-emphasis coefficients from said parameters.
Claim 2
Independent Claim
98 words
An apparatus for calculating pre-emphasis coefficients for a transmitting modem in a communications system, including: first transmitting means in the transmitting modem, including adjusting means responsive to the pre-emphasis coefficients for adjusting frequency-dependent characteristics of an output of said first transmitting means; receiving means for receiving said output from said first transmitting means; generating means for generating parameters responsive to a noise spectrum of said output including means for calculating said noise spectrum of said output; second transmitting means for transmitting said parameters to the transmitting modem, and computing means for computing the pre-emphasis coefficients from said parameters.
Claim 3
Dependent Claim
15 words
The apparatus of claim 1 wherein said adjusting means includes a filter with several taps.
Claim 4
Dependent Claim
13 words
The apparatus of claim 2 wherein said filter includes at least nine taps.
Claim 5
Dependent Claim
15 words
The apparatus of claim 1 wherein said generating means includes a noise spectrum generator circuit.
Claim 6
Dependent Claim
63 words
The apparatus of claim 4 wherein said noise spectrum generator circuit includes: determining means for determining best-fit transmitted data points from said output of said first transmitting means as received by said receiving means; comparing means for determining a difference between said best-fit transmitted data points and said output as received by said receiving means thereby calculating said noise spectrum of said output.
Claim 7
Independent Claim
231 words
An apparatus for calculating pre-emphasis coefficients for a transmitting modem in a communications systems, including: first transmitting means in the transmitting modem, including adjusting means responsive to the pre-emphasis coefficients for adjusting frequency-dependent characteristics of an output of said first transmitting means; receiving means for receiving said output from said first transmitting means; generating means, including a noise spectrum generator circuit, for generating parameters responsive to a noise spectrum of said output; second transmitting means for transmitting said parameters to the transmitting modem; and computing means for computing the pre-emphasis coefficients from said parameters; wherein said noise spectrum generator circuit includes determining means for determining best-fit transmitted data points from said output of said first transmitting means as received by said receiving means; and comparing means for determining a difference between said best-fit transmitted data points and said output as received by said receiving means; wherein said receiving means includes analog-to-digital conversion means and demodulating means which generates a complex signal; and wherein said noise spectrum generator circuit includes a phase corrector responsive to said complex signal; a slicer which determines, from said complex signal, best-fit transmitted data points from said first transmitted means; subtracting means for determining a difference between said best-fit transmitted data points and said complex signal; an inverse phase corrector responsive to said difference; and a complex discrete Fourier transform block responsive to said inverse phase corrector.
Claim 8
Independent Claim
231 words
An apparatus for calculating pre-emphasis coefficients for a transmitting modem in a communications systems, including: first transmitting means in the transmitting modem, including adjusting means responsive to the pre-emphasis coefficients for adjusting frequency-dependent characteristics of an output of said first transmitting means; receiving means for receiving said output from said first transmitting means; generating means, including a noise spectrum generator circuit, for generating parameters responsive to a noise spectrum of said output; second transmitting means for transmitting said parameters to the transmitting modem; and computing means for computing the pre-emphasis coefficients from said parameters; wherein said noise spectrum generator circuit includes determining means for determining best-fit transmitted data points from said output of said first transmitting means as received by said receiving means; and comparing means for determining a difference between said best-fit transmitted data points and said output as received by said receiving means; wherein said receiving means includes analog-to-digital conversion means and demodulating means which generates a complex signal; and wherein said noise spectrum generator circuit includes a phase corrector responsive to said complex signal; a slicer which determines, from said complex signal, best-fit transmitted data points from said first transmitted means; subtracting means for determining a difference between said best-fit transmitted data points and said complex signal; an inverse phase corrector responsive to said difference; and a complex discrete Fourier transform block responsive to said inverse phase corrector.
Claim 9
Dependent Claim
26 words
The apparatus of claim 6 wherein said phase corrector is responsive to equalization means and wherein said equalization means is responsive to said inverse phase corrector.
Claim 10
Independent Claim
154 words
An apparatus for calculating pre-emphasis coefficients for a transmitting modem in a communications systems, including: first transmitting means in the transmitting modem, including adjusting means responsive to the pre-emphasis coefficients for adjusting frequency-dependent characteristics of an output of said first transmitting means; receiving means for receiving said output from said first transmitting means; generating means, including a noise spectrum generator circuit, for generating parameters responsive to a noise spectrum of said output; second transmitting means for transmitting said parameters to the transmitting modem; and computing means for computing the pre-emphasis coefficients from said parameters; wherein said noise spectrum generator circuit includes determining means for determining best-fit transmitted data points from said output of said first transmitting means as received by said receiving means; and comparing means for determining a difference between said best-fit transmitted data points and said output as received by said receiving means; and wherein said determining means includes eye pattern data.
Claim 11
Independent Claim
154 words
An apparatus for calculating pre-emphasis coefficients for a transmitting modem in a communications systems, including: first transmitting means in the transmitting modem, including adjusting means responsive to the pre-emphasis coefficients for adjusting frequency-dependent characteristics of an output of said first transmitting means; receiving means for receiving said output from said first transmitting means; generating means, including a noise spectrum generator circuit, for generating parameters responsive to a noise spectrum of said output; second transmitting means for transmitting said parameters to the transmitting modem; and computing means for computing the pre-emphasis coefficients from said parameters; wherein said noise spectrum generator circuit includes determining means for determining best-fit transmitted data points from said output of said first transmitting means as received by said receiving means; and comparing means for determining a difference between said best-fit transmitted data points and said output as received by said receiving means; and wherein said determining means includes eye pattern data.
Claim 12
Independent Claim
172 words
An apparatus for calculating pre-emphasis coefficients for a transmitting modem in a communications systems, including: first transmitting means in the transmitting modem, including adjusting means responsive to the pre-emphasis coefficients for adjusting frequency-dependent characteristics of an output of said first transmitting means; receiving means for receiving said output from said first transmitting means; generating means, including a noise spectrum generator circuit, for generating parameters responsive to a noise spectrum of said output; second transmitting means for transmitting said parameters to the transmitting modem; and computing means for computing the pre-emphasis coefficients from said parameters; wherein said noise spectrum generator circuit includes determining means for determining best-fit transmitted data points from said output of said first transmitting means as received by said receiving means; and comparing means for determining a difference between said best-fit transmitted data points and said output as received by said receiving means; and wherein said generating means includes discrete Fourier transform means responsive to said difference, thereby calculating a frequency domain representation of said noise spectrum of said output.
Claim 13
Independent Claim
172 words
An apparatus for calculating pre-emphasis coefficients for a transmitting modem in a communications systems, including: first transmitting means in the transmitting modem, including adjusting means responsive to the pre-emphasis coefficients for adjusting frequency-dependent characteristics of an output of said first transmitting means; receiving means for receiving said output from said first transmitting means; generating means, including a noise spectrum generator circuit, for generating parameters responsive to a noise spectrum of said output; second transmitting means for transmitting said parameters to the transmitting modem; and computing means for computing the pre-emphasis coefficients from said parameters; wherein said noise spectrum generator circuit includes determining means for determining best-fit transmitted data points from said output of said first transmitting means as received by said receiving means; and comparing means for determining a difference between said best-fit transmitted data points and said output as received by said receiving means; and wherein said generating means includes discrete Fourier transform means responsive to said difference, thereby calculating a frequency domain representation of said noise spectrum of said output.
Claim 14
Dependent Claim
41 words
The apparatus of claim 8 wherein said generating means further includes discrete Fourier transform means responsive to said difference, thereby calculating a frequency domain representation and storing the values of the frequency domain representation of a noise spectrum of said output.
Claim 15
Dependent Claim
26 words
The apparatus of claim 10, wherein said computing means includes subtracting means for subtracting previously stored values from said frequency domain representation thereby calculating second differences.
Claim 16
Dependent Claim
18 words
The apparatus of claim 11 wherein said computing means further includes dividing means for dividing said second differences.
Claim 17
Dependent Claim
12 words
The apparatus of claim 12 wherein said dividing means divides by two.
Claim 18
Dependent Claim
14 words
The apparatus of claim 11 wherein said second differences replace said previously stored values.
Claim 19
Dependent Claim
15 words
The apparatus of claim 1 wherein said second transmitting means transmits over a secondary channel.
Claim 20
Dependent Claim
20 words
The apparatus of claim 15 wherein said secondary channel is a sideband of a channel of said first transmitting means.
Claim 21
Dependent Claim
20 words
The apparatus of claim 16 wherein said receiving means and said second transmitting means are incorporated into a single circuit.
Claim 22
Dependent Claim
17 words
The apparatus of claim 1 wherein said computing means converts said parameters from logarithmic to linear scale.
Claim 23
Dependent Claim
23 words
The apparatus of claim 1 wherein said computing means adjusts said parameters iteratively to adjust for resonator frequencies of said first transmitting means.
Claim 24
Dependent Claim
23 words
The apparatus of claim 1 wherein said computing means adjusts said parameters to assure a constant power output of said first transmitting means.
Claim 25
Independent Claim
77 words
A method for calculating pre-emphasis coefficients for a transmitting modem in a communications systems, including the steps of: transmitting from the transmitting modem; adjusting frequency characteristics of output from said transmitting step responsive to the pre-emphasis coefficients; receiving said output from said first transmitting means; calculating a noise spectrum of said output; generating parameters responsive to said noise spectrum of said output; sending said parameters to the transmitting modem; and computing the pre-emphasis coefficients from said parameters.
Claim 26
Independent Claim
77 words
A method for calculating pre-emphasis coefficients for a transmitting modem in a communications systems, including the steps of: transmitting from the transmitting modem; adjusting frequency characteristics of output from said transmitting step responsive to the pre-emphasis coefficients; receiving said output from said first transmitting means; calculating a noise spectrum of said output; generating parameters responsive to said noise spectrum of said output; sending said parameters to the transmitting modem; and computing the pre-emphasis coefficients from said parameters.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-04-15 | 1994-10-15 | 1995-04-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-04-15 | 1998-10-15 | 1999-04-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-04-15 | 2002-10-15 | 2003-04-16 | $7700.00 | Window Closed / Lapsed |