Patent BE536119A successfully refreshed from Google Patents.
Patent EP0397535A2 successfully refreshed from Google Patents.
EP0397535A2
Expired / Lapsed
EP
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Modem
Assignee: Motorola Solutions Inc
•
Filing: 1990-05-14
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Granted: —
•
Expires: 2010-05-14
Abstract
Abstract A modem receives data sent from a remote device over a communication channel by using a single carrier modulated signal. The modem includes a receiver which receives the modulated signal and a line probing signal sent by the remote device over the channel. The receiver is capable of receiving the modulated signal over any one of a plurality of frequency bands. A line probing processor measures characteristics of the channel based upon the received line probing signal. A selector selects one of the plurality of frequency bands, this selection being based upon the measured characteristics of the channel. The selected frequency band is to be used for receiving the modulated signal from the remote device.
Inventors
- 👤 Vedat M. Eyuboglu
- 👤 Ping Dong
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 02:33
CPC Classifications
H; H04; H04L; H04L1/00; H04L1/20; H04L1/206
Claims Analysis
Total Claims: 67
Claim 1
Independent Claim
123 words
A modem for receiving data sent from a remote device over a communication channel by using a single carrier modulated signal, the modem comprising: a. a receiver for receiving the modulated signal and for receiving a line probing signal sent by the remote device over the channel, the receiver being capable of receiving the modulated signal over any one of a plurality of frequency bands; b. a line probing processor for measuring characteristics of the channel based upon the received line probing signal; and c. a selector for selecting one of the plurality of frequency bands, said selection being based upon the measured characteristics of the channel, said selected frequency band to be used for receiving the modulated signal from the remote device.
Claim 2
Dependent Claim
123 words
A modem for receiving data sent from a remote device over a communication channel by using a single carrier modulated signal, the modem comprising: a. a receiver for receiving the modulated signal and for receiving a line probing signal sent by the remote device over the channel, the receiver being capable of receiving the modulated signal over any one of a plurality of frequency bands; b. a line probing processor for measuring characteristics of the channel based upon the received line probing signal; and c. a selector for selecting one of the plurality of frequency bands, said selection being based upon the measured characteristics of the channel, said selected frequency band to be used for receiving the modulated signal from the remote device.
Claim 3
Dependent Claim
60 words
The modem of claim 1 wherein the line probing processor comprises: a. a spectrum analyzer for generating discrete spectral representations of the received line probing signal; and b. a module for estimating a frequency response for the channel based upon the discrete spectral representations of the received line probing signal, the frequency response being estimated at more than one frequency.
Claim 4
Dependent Claim
51 words
The modem of claim 1 wherein the line probing processor comprises: a. a spectrum analyzer for generating discrete spectral representations of the received line probing signal; and b. a module for estimating a power spectral density of channel noise based upon the discrete spectral representations of the received line probing signal.
Claim 5
Dependent Claim
37 words
The modem of claims 1, 2, or 3 wherein the modulated signal is a linearly modulated signal and wherein each one of said plurality of frequency bands is characterized by a corresponding baud rate and carrier frequency.
Claim 6
Dependent Claim
23 words
The modem of claim 4 wherein the carrier frequency of one or more of said plurality of frequency bands is equal to zero.
Claim 7
Dependent Claim
16 words
The modem of claim 4 wherein the linearly modulated signal is a quadrature amplitude modulated signal.
Claim 8
Dependent Claim
16 words
The modem of claim 1 wherein the measured characteristics include a frequency response of the channel.
Claim 9
Dependent Claim
37 words
The modem of claim 1 wherein the receiver includes an adaptive filter for providing a desired overall impulse response to a decoder and wherein at least some of the measured characteristics take into account the adaptive filter.
Claim 10
Dependent Claim
16 words
The modem of claim 8 wherein the adaptive filter is used in conjunction with trellis precoding.
Claim 11
Dependent Claim
23 words
The modem of claim 1 wherein the measured characteristics further include a signal-to-noise ratio of the channel measured at more than one frequency.
Claim 12
Dependent Claim
15 words
The modem of claim 1 wherein the line probing signal is a substantially periodic signal.
Claim 13
Dependent Claim
98 words
The modem of claim 11 wherein the line probing signal is of the form: x(t) = A Σ k cos(2πkf Δ t + ϑ k ), where x(t) represents the line probing signal; t is a time variable; A is a constant; f Δ is a frequency resolution; ϑ k is a phase angle; k is a frequency interval index which belongs to a subset of the integers ranging from k₁ through k₂; k₁ specifies the lowest frequency index included in the line probing signal; and k₂ specifies the highest frequency index included in the line probing signal.
Claim 14
Dependent Claim
29 words
The modem of claim 12 wherein the phase angles ϑ k of the line probing signal are selected to achieve a small peak-to-average ratio of the line probing signal.
Claim 15
Dependent Claim
23 words
The modem of claim 12 wherein the phase angles ϑ k of the line probing signal are equal to: ϑ k = π(k-k₂)²/(k₂-k₁)
Claim 16
Dependent Claim
33 words
The modem of claim 3 wherein the module performs weighted periodogram averaging to estimate the power spectral density of channel noise based upon the discrete spectral representations of the received line probing signal.
Claim 17
Dependent Claim
57 words
The modem of claim 15 wherein the module also estimates a power spectrum of the channel response based upon the discrete spectral representations of the received line probing signal and then computes a signal-to-noise ratio corresponding to the channel based upon both the power spectral density of channel noise and the power spectrum of the channel response.
Claim 18
Dependent Claim
31 words
The modem of claim 16 wherein the power spectrum of the channel response and the power spectral density of channel noise are estimated concurrently from the same received line probing signal.
Claim 19
Dependent Claim
37 words
The modem of claim 16 wherein the receiver further comprises an adaptive filter for providing a desired overall impulse response to a decoder and the signal-to-noise ratio is determined relative to the output of the adaptive filter.
Claim 20
Dependent Claim
16 words
The modem of claim 18 wherein the adaptive filter is used in conjuction with trellis precoding.
Claim 21
Dependent Claim
61 words
The modem of claim 1 further comprising a transmitter for transmitting information based upon the measured characteristics to the remote device so that the remote device may identify one of said plurality of frequency bands based upon said transmitted information and then communicate said identified band to the receiver and wherein the selector selects the identified band as said selected band.
Claim 22
Dependent Claim
60 words
The modem of claim 3 wherein received line probing signal may include an impairment (e.g. frequency offset and/or low frequency phase jitter) and wherein the line probing processor further comprises an offset monitor for reducing effects of said impairment on the discrete representation of the received signal prior its being used to determine the power spectral density of channel noise.
Claim 23
Dependent Claim
73 words
The modem of claim 21 wherein the line probing signal is substantially periodic and the discrete spectral representations are generated for each period of the received line probing signal and wherein the offset monitor reduces the effects of said impairment by first estimating said impairment and by then rotating the discrete representation corresponding to a current period of the received line probing signal by an amount determined by the estimate of said impairment.
Claim 24
Dependent Claim
52 words
The modem of claim 22 wherein the offset monitor estimates said impairment by comparing the discrete spectral representation corresponding to the current period of the received line probing signal to a reference signal derived from the discrete spectral representations corresponding to at least one previous period of the received line probing signal.
Claim 25
Dependent Claim
23 words
The modem of claim 2 or 3 wherein the discrete spectral representations of the received line probing signal are M-point Discrete Fourier Transforms.
Claim 26
Dependent Claim
67 words
The modem of claim 1 wherein the receiver is also capable of receiving the modulated signal at any one of a plurality of bit rates and wherein the modem further comprises logic for selecting one of the plurality of different bit rates based upon the measured characteristics of the receiver channel, said selected bit rate to be used for receiving the modulated signal from the remote device.
Claim 27
Dependent Claim
48 words
The modem of claim 25 wherein the line probing processor comprises: a. a spectrum analyzer for generating discrete spectral representations of the received line probing signal; and b. a module for computing a nonlinear distortion indicator based upon the discrete spectral representations of the received line probing signal.
Claim 28
Dependent Claim
37 words
The modem of claim 25 wherein the receiver comprises a monitor circuit for measuring a power level of the received line probing signal and wherein the measured characteristics includes a quantity derived from the received power level.
Claim 29
Dependent Claim
138 words
A modem for transmitting data to a remote device over a communication channel by using a single carrier modulated signal, the modem comprising: a. a signal generator for generating a line probing signal; b. a transmitter for transmitting the modulated signal and for transmitting the line probing signal to the remote device over the channel, the transmitter being capable of transmitting the modulated signal over any one of a plurality of frequency bands; c. a receiver for receiving characteristics of the channel from the remote device, the characteristics being derived by the remote device from the transmitted line probing signal; and d. a selector for selecting one of the plurality of frequency bands, said selection being based upon the measured channel characteristics, the selected frequency band to be used for transmitting the modulated signal to the remote device.
Claim 30
Dependent Claim
138 words
A modem for transmitting data to a remote device over a communication channel by using a single carrier modulated signal, the modem comprising: a. a signal generator for generating a line probing signal; b. a transmitter for transmitting the modulated signal and for transmitting the line probing signal to the remote device over the channel, the transmitter being capable of transmitting the modulated signal over any one of a plurality of frequency bands; c. a receiver for receiving characteristics of the channel from the remote device, the characteristics being derived by the remote device from the transmitted line probing signal; and d. a selector for selecting one of the plurality of frequency bands, said selection being based upon the measured channel characteristics, the selected frequency band to be used for transmitting the modulated signal to the remote device.
Claim 31
Dependent Claim
34 words
The modem of claim 28 wherein the modulated signal is a linearly modulated signal and wherein each one of said plurality of frequency bands is characterized by a corresponding baud rate and carrier frequency.
Claim 32
Dependent Claim
16 words
The modem of claim 29 wherein the linearly modulated signal is a quadrature amplitude modulated signal.
Claim 33
Dependent Claim
16 words
The modem of claim 28 wherein the measured characteristics include a frequency response of the channel.
Claim 34
Dependent Claim
23 words
The modem of claim 28 wherein the measured characteristics further include a signal-to-noise ratio of the channel measured at more than one frequency.
Claim 35
Dependent Claim
15 words
The modem of claim 28 wherein the line probing signal is a substantially periodic signal.
Claim 36
Dependent Claim
98 words
The modem of claim 33 wherein the line probing signal is of the form: x(t) = A Σ k cos(2πkf Δ t + ϑ k ), where x(t) represents the line probing signal; t is a time variable; A is a constant; f Δ is a frequency resolution; ϑ k is a phase angle; k is a frequency interval index which belongs to a subset of the integers ranging from k₁ through k₂; k₁ specifies the lowest frequency index included in the line probing signal; and k₂ specifies the highest frequency index included in the line probing signal.
Claim 37
Dependent Claim
29 words
The modem of claim 34 wherein the phase angles ϑ k of the line probing signal are selected to achieve a small peak-to-average ratio for the line probing signal.
Claim 38
Dependent Claim
23 words
The modem of claim 34 wherein the phase angles ϑ k of the line probing signal are equal to: ϑ k = π(k-k₂)²/(k₂-k₁)
Claim 39
Dependent Claim
124 words
A modem for receiving data sent from a remote device over a communication channel by using a single carrier modulated signal, the modem comprising: a. a receiver for receiving the modulated signal and for receiving a line probing signal sent by the remote device over the channel, the receiver being capable of receiving the modulated signal at any one of a plurality of bit rates; b. a line probing processor for measuring characteristics of the channel based upon the received line probing signal; and c. a selector for selecting one of the plurality of bit rates, said selection being based upon the measured characteristics of the receiver channel, the selected bit rate to be used for receiving the modulated signal from the remote device.
Claim 40
Dependent Claim
124 words
A modem for receiving data sent from a remote device over a communication channel by using a single carrier modulated signal, the modem comprising: a. a receiver for receiving the modulated signal and for receiving a line probing signal sent by the remote device over the channel, the receiver being capable of receiving the modulated signal at any one of a plurality of bit rates; b. a line probing processor for measuring characteristics of the channel based upon the received line probing signal; and c. a selector for selecting one of the plurality of bit rates, said selection being based upon the measured characteristics of the receiver channel, the selected bit rate to be used for receiving the modulated signal from the remote device.
Claim 41
Dependent Claim
60 words
The modem of claim 37 wherein the line probing processor comprises: a. a spectrum analyzer for generating discrete spectral representations of the received line probing signal; and b. a module for estimating a frequency response for the channel based upon the discrete spectral representations of the received line probing signal, the frequency response being estimated at more than one frequency.
Claim 42
Dependent Claim
51 words
The modem of claims 37 wherein the line probing processor comprises: a. a spectrum analyzer for generating discrete spectral representations of the received line probing signal; and b. a module for estimating a power spectral density of channel noise based upon the discrete spectral representations of the received line probing signal.
Claim 43
Dependent Claim
17 words
The modem of claims 37, 38, or 39 wherein the modulated signal is a linearly modulated signal.
Claim 44
Dependent Claim
16 words
The modem of claim 40 wherein the linearly modulated signal is a quadrature amplitude modulated signal.
Claim 45
Dependent Claim
16 words
The modem of claim 40 wherein the measured characteristics include a frequency response of the channel.
Claim 46
Dependent Claim
22 words
The modem of claim 37 wherein the measured characteristics include a signal-to-noise ratio of the channel measured at more than one frequency.
Claim 47
Dependent Claim
15 words
The modem of claim 37 wherein the line probing signal is a substantially periodic signal.
Claim 48
Dependent Claim
98 words
The modem of claim 44 wherein the line probing signal is of the form: x(t) = A Σ k cos(2πkf Δ t + ϑ k ), where x(t) represents the line probing signal; t is a time variable; A is a constant; f Δ is a frequency resolution; ϑ k is a phase angle; k is a frequency interval index which belongs to a subset of the integers ranging from k₁ through k₂; k₁ specifies the lowest frequency index included in the line probing signal; and k₂ specifies the highest frequency index included in the line probing signal.
Claim 49
Dependent Claim
29 words
The modem of claim 45 wherein the phase angles ϑ k of the line probing signal are selected to achieve a small peak-to-average ratio for the line probing signal.
Claim 50
Dependent Claim
23 words
The modem of claim 45 wherein the phase angles ϑ k of the line probing signal are equal to: ϑ k = π(k-k₂)²/(k₂-k₁)
Claim 51
Dependent Claim
32 words
The modem of claim 39 wherein the module performs weighted periodogram averaging to estimate the power spectral density of channel noise from the discrete spectral representations of the received line probing signal.
Claim 52
Dependent Claim
57 words
The modem of claim 48 wherein the module also estimates a power spectrum of the channel response based upon the discrete spectral representations of the received line probing signal and then computes a signal-to-noise ratio corresponding to the channel based upon both the power spectral density of channel noise and the power spectrum of the channel response.
Claim 53
Dependent Claim
27 words
The modem of claim 49 wherein the power spectrum and the spectral power density of channel noise are estimated concurrently from the same received line probing signal.
Claim 54
Dependent Claim
38 words
The modem of claim 37 wherein the receiver further comprises an adaptive filter for providing a desired overall impulse response to a decoder and wherein at least some of the measured characteristics take into account the adaptive filter.
Claim 55
Dependent Claim
16 words
The modem of claim 51 wherein the adaptive filter is used in conjuction with trellis precoding.
Claim 56
Dependent Claim
63 words
The modem of claim 37 further comprising a transmitter for transmitting information based upon the measured characteristics to the remote device so that the remote device may identify one of said plurality of bit rates based upon said information and then communicate said identified bit rate to the receiver and wherein the selector selects the identified bit rate as said selected bit rate.
Claim 57
Dependent Claim
60 words
The modem of claim 39 wherein received line probing signal may include an impairment (e.g. frequency offset and/or low frequency phase jitter) and wherein the line probing processor further comprises an offset monitor for reducing effects of said impairment on the discrete representation of the received signal prior its being used to determine the power spectral density of channel noise.
Claim 58
Dependent Claim
73 words
The modem of claim 54 wherein the line probing signal is substantially periodic and a discrete spectral representation is generated for each period of the received line probing signal and wherein the offset monitor reduces the effects of said impairment by first estimating said impairment and by then rotating the discrete representation corresponding to a current period of the received line probing signal by an amount determined by the estimate of said impairment.
Claim 59
Dependent Claim
52 words
The modem of claim 55 wherein the offset monitor estimates said impairment by comparing the discrete spectral representation corresponding to the current period of the received line probing signal to a reference signal derived from the discrete spectral representations corresponding to at least one previous period of the received line probing signal.
Claim 60
Dependent Claim
48 words
The modem of claim 37 wherein the line probing processor comprises: a. a spectrum analyzer for generating discrete spectral representations of the received line probing signal; and b. a module for computing a nonlinear distortion indicator based upon the discrete spectral representations of the received line probing signal.
Claim 61
Dependent Claim
37 words
The modem of claim 37 wherein the receiver comprises a monitor circuit for measuring a power level of the received line probing signal and wherein the measured characteristics includes a quantity derived from the received power level.
Claim 62
Dependent Claim
147 words
In a system in which a local modem receives data sent by a remote device over a receiver channel in the form of a first single carrier modulated signal, the modem being capable of receiving the first modulated signal over any one of a first plurality of frequency bands, a method for establishing communication conditions comprising the steps of: a. sending a first line probing signal from the remote device to the local modem over the receiver channel; b. receiving the first line probing signal in the local modem; c. measuring characteristics of the receiver channel based upon the received first line probing signal; and d. selecting one of the first plurality of frequency bands based upon the measured characteristics of the receiver channel, said selected one of the first plurality of frequency bands to be used for receiving the first modulated signal from the remote device.
Claim 63
Dependent Claim
147 words
In a system in which a local modem receives data sent by a remote device over a receiver channel in the form of a first single carrier modulated signal, the modem being capable of receiving the first modulated signal over any one of a first plurality of frequency bands, a method for establishing communication conditions comprising the steps of: a. sending a first line probing signal from the remote device to the local modem over the receiver channel; b. receiving the first line probing signal in the local modem; c. measuring characteristics of the receiver channel based upon the received first line probing signal; and d. selecting one of the first plurality of frequency bands based upon the measured characteristics of the receiver channel, said selected one of the first plurality of frequency bands to be used for receiving the first modulated signal from the remote device.
Claim 64
Dependent Claim
139 words
The method of claim 59 wherein the modem transmits data to the remote device over a transmitter channel by using a second single carrier modulated signal and being capable of sending the second signal over any one of a second plurality of frequency bands, the method further comprising the steps of: a. sending a second line probing signal from the local modem to the remote device over the transmitter channel; b. receiving the second line probing signal in the remote device; c. measuring characteristics of the transmitter channel based upon the received second line probing signal; and d. selecting one of the second plurality of frequency bands based upon the measured characteristics of the transmission channel, said selected one of the second plurality of frequency bands to be used for sending the second modulated signal to the remote device.
Claim 65
Dependent Claim
147 words
In a system in which a local modem receives data sent by a remote device over a receiver channel in the form of a first single carrier modulated signal, the modem being capable of receiving the first modulated signal at any one of a first plurality of bit rates, a method for establishing communication conditions comprising the steps of: a. sending a first line probing signal from the remote device to the local modem over the receiver channel; b. receiving the first line probing signal in the local modem; c. measuring characteristics of the receiver channel based upon the received first line probing signal; and d. selecting one of the first plurality of bit rates based upon the measured characteristics of the receiver channel, said selected one of the first plurality of bit rates to be used for receiving the first modulated signal from the remote device.
Claim 66
Dependent Claim
147 words
In a system in which a local modem receives data sent by a remote device over a receiver channel in the form of a first single carrier modulated signal, the modem being capable of receiving the first modulated signal at any one of a first plurality of bit rates, a method for establishing communication conditions comprising the steps of: a. sending a first line probing signal from the remote device to the local modem over the receiver channel; b. receiving the first line probing signal in the local modem; c. measuring characteristics of the receiver channel based upon the received first line probing signal; and d. selecting one of the first plurality of bit rates based upon the measured characteristics of the receiver channel, said selected one of the first plurality of bit rates to be used for receiving the first modulated signal from the remote device.
Claim 67
Dependent Claim
139 words
The method of claim 61 wherein the modem transmits data to the remote device over a transmitter channel by using a second single carrier modulated signal and is capable of sending the second signal at any one of a second plurality of bit rates, the method further comprising the steps of: a. sending a second line probing signal from the local modem to the remote device over the transmitter channel; b. receiving the second line probing signal in the remote device; c. measuring characteristics of the transmitter channel based upon the received second line probing signal; and d. selecting one of the second plurality of bit rates based upon the measured characteristics of the transmission channel, said selected one of the second plurality of bit rates to be used for sending the second modulated signal to the remote device.
References Cited (Backward Citations)
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