Block spectrum receiver for a broadband communications system

Claim 1

A system for coupling telephony signals modulated on a carrier in a predetermined spectral subband of a broadband communication network from a subscriber to a telephony network interface, comprising: a tuner for tuning to and selecting the predetermined spectral subband; a block channelizer for collecting a group of telephony signals from said tuner and providing time division multiple access (TDMA) sampled signals corresponding to the modulated telephony signals at baseband; a baseband demodulator for demodulating the TDMA sampled signals and deriving demodulated telephony signals; and an output interface for coupling said demodulated telephony signals to a telephony network, wherein the baseband demodulator comprises: an input port for receiving a serial data stream comprising a plurality of digital signal samples representing a plurality of QPSK-modulated DS0 telephony channels at baseband; an automatic gain control (AGC) stage for adjusting the gain of the digital signal samples for each of the DSO telephony channels; a symbol timing recovery (STR) stage coupled to the AGC stage for extracting timing information for each of the QPSK-modulated DSO telephony channels from the digital signal samples and delaying the sampling of the digital signal samples at a decoding stage to a time such that the sampling will be at optimized symbol instants; a carrier phase recovery (CPR) stage coupled to the STR stage for locking the demodulator to the frequency of the carrier for each of the QPSK-modulated DS0 telephony signals; and a symbol decoding stage for sampling the digital signal samples and providing a digital signal output corresponding to the demodulated DS0 telephony channels.

Claim 2

A system for coupling telephony signals modulated on a carrier in a predetermined spectral subband of a broadband communication network from a subscriber to a telephony network interface, comprising: a tuner for tuning to and selecting the predetermined spectral subband; a block channelizer for collecting a group of telephony signals from said tuner and providing time division multiple access (TDMA) sampled signals corresponding to the modulated telephony signals at baseband; a baseband demodulator for demodulating the TDMA sampled signals and deriving demodulated telephony signals; and an output interface for coupling said demodulated telephony signals to a telephony network, wherein the baseband demodulator comprises: an input port for receiving a serial data stream comprising a plurality of digital signal samples representing a plurality of QPSK-modulated DS0 telephony channels at baseband; an automatic gain control (AGC) stage for adjusting the gain of the digital signal samples for each of the DSO telephony channels; a symbol timing recovery (STR) stage coupled to the AGC stage for extracting timing information for each of the QPSK-modulated DSO telephony channels from the digital signal samples and delaying the sampling of the digital signal samples at a decoding stage to a time such that the sampling will be at optimized symbol instants; a carrier phase recovery (CPR) stage coupled to the STR stage for locking the demodulator to the frequency of the carrier for each of the QPSK-modulated DS0 telephony signals; and a symbol decoding stage for sampling the digital signal samples and providing a digital signal output corresponding to the demodulated DS0 telephony channels.

Claim 6

A method of processing telephony signals communicated in an upstream frequency spectral band from subscribers in a broadband communication system, comprising the steps of: modulating upstream telephony signals on single carrier per channel, the carriers for each channel being coherently harmonically related; selecting a predetermined spectral subband in said upstream frequency spectral band containing a contiguous plurality of telephony signal channels; tuning to the center frequency of said selected predetermined spectral subband; downconverting said selected spectral subband to a lower center frequency; digitizing said selected spectral subband to obtain a plurality of digital signal samples representing said selected spectral subband; block processing all channels within said selected spectral subband to derive separate digital baseband signals representing said contiguous plurality of telephony signal channels; and demodulating said separate digital baseband signals to provide individual demodulated telephony signals, wherein block processing all channels within said selected spectral subband comprises the steps of: block filtering said plurality of digital signal samples to effect a half Nyquist filter matched to a half Nyquist filter at a subscriber; and downconverting each of said channels to baseband with a digital fast Fourier transform (FFT) operation.

Claim 7

A method of processing telephony signals communicated in an upstream frequency spectral band from subscribers in a broadband communication system, comprising the steps of: modulating upstream telephony signals on single carrier per channel, the carriers for each channel being coherently harmonically related; selecting a predetermined spectral subband in said upstream frequency spectral band containing a contiguous plurality of telephony signal channels; tuning to the center frequency of said selected predetermined spectral subband; downconverting said selected spectral subband to a lower center frequency; digitizing said selected spectral subband to obtain a plurality of digital signal samples representing said selected spectral subband; block processing all channels within said selected spectral subband to derive separate digital baseband signals representing said contiguous plurality of telephony signal channels; and demodulating said separate digital baseband signals to provide individual demodulated telephony signals, wherein block processing all channels within said selected spectral subband comprises the steps of: block filtering said plurality of digital signal samples to effect a half Nyquist filter matched to a half Nyquist filter at a subscriber; and downconverting each of said channels to baseband with a digital fast Fourier transform (FFT) operation.

Claim 9

A system for coupling telephony signals modulated on a carrier in a predetermined first band of frequencies in a cable television (CATV) network from a subscriber to a telephony network interface, comprising: a tuner for tuning to and selecting the predetermined spectral subband; a block channelizer for collecting a group of telephony signals from said tuner and providing time division multiple access (TDMA) sampled signals corresponding to the modulated telephony signals at baseband; a baseband demodulator for demodulating the TDMA sampled signals and deriving demodulated telephony signals; an output interface for coupling said demodulated telephony signals to a telephony network; equipment for providing television program signals to subscribers in a predetermined second band of frequencies; and a frequency agile modulator located at the subscriber operative to change the frequency at which telephony signals are communicated from a first frequency in the first band of frequencies to a second frequency in the first band of frequencies in response to a command received from a control device.

Claim 10

A system for coupling telephony signals modulated on a carrier in a predetermined first band of frequencies in a cable television (CATV) network from a subscriber to a telephony network interface, comprising: a tuner for tuning to and selecting the predetermined spectral subband; a block channelizer for collecting a group of telephony signals from said tuner and providing time division multiple access (TDMA) sampled signals corresponding to the modulated telephony signals at baseband; a baseband demodulator for demodulating the TDMA sampled signals and deriving demodulated telephony signals; an output interface for coupling said demodulated telephony signals to a telephony network; equipment for providing television program signals to subscribers in a predetermined second band of frequencies; and a frequency agile modulator located at the subscriber operative to change the frequency at which telephony signals are communicated from a first frequency in the first band of frequencies to a second frequency in the first band of frequencies in response to a command received from a control device.