Modulator for a broadband communications system

In a bidirectional communications system comprising a plurality of customer interface unite (CIU), each defining a destination for incoming data and an origin for outgoing data and including a multi-channel modulator for generating modulated signals within discrete increment channels of a frequency band of the bidirectional communications system by modulating assigned carriers for a plurality of upstream channels with a outgoing data, the multi-channel modulator comprising;

• filter, responsive to in-phase (I) signal components and quadrature (Q) signal components of the outgoing data, for filtering the I signal components and the Q signal components to generate filtered I and Q signal components;
• a plurality of channel modulators, each of the channel modulators responsive to the filtered I and Q signal components for modulating a selected one of the assigned carriers for the plurality of upstream channels with the outgoing data to produce a complex modulated signal having a real signal component and an imaginary signal component;
• an adder module, responsive to the complex modulated signal generated by each of the channel modulators, for summing the real signal component of each channel modulator to produce a real resultant signal and for summing the imaginary signal component of each channel modulator to produce an imaginary resultant signal;
• a digital-to-analog converter (DAC) module for converting the real resultant signal and the imaginary resultant signal to analog signals;
• and
• a transmitter, responsive to the analog signals, for transmitting the modulated signals within the discrete increment channels.

A customer interface unit (CIU) for connection to a broadband communication network, the CIU operative for receiving first signals in a first frequency band from a headend associated with the broadband communication network and for communicating telephony signals between a subscriber and the headend in a second frequency band of the broadband communication network, the customer interface unit comprising:

• a first demodulator for demodulating the first signals in the first frequency band to produce demodulated first signals and for coupling the demodulated first signals to an output port of the customer interface unit;
• and
• a multi-channel modulator for generating modulated signals in the second frequency band by modulating carrier signals in accordance with the telephony signals, each of the telephony signals including in-phase (I) and quadrature (Q) signal components, the multi-channel modulator comprising:
• a filter for filtering the I and Q signal components to produce filtered I and Q signal components;
• an interpolation module for generating processed I and Q signal components by upsampling the filtered I and Q signal components;
• a plurality of channel modulators, each of the channel modulators responsive to the processed I and Q signal components for modulating a selected one of the carrier signals with a selected one of the telephony signals to produce a complex modulated signal having a real signal component and an imaginary signal component;
• an adder module, responsive to the complex modulated signal generated by each of the channel modulators, for summing the real signal component of each channel modulator to produce a real resultant signal and for summing the imaginary signal component of each channel modulator to produce an imaginary resultant signal;
• a digital-to-analog converter (DAC) module for converting the real resultant signal and the imaginary resultant signal to analog signals;
• and
• a transmitter, responsive to the analog signals, for transmitting the modulated signals within the second frequency band of the broadband communications network.

A customer interface unit (CIU) for connection to a broadband communication network, the CIU operative for receiving first signals in a first frequency band from a headend associated with the broadband communication network, for receiving second signals from the headend, and for communicating telephony signals between a subscriber and the headend, said customer interface unit comprising:

• a first demodulator for demodulating the first signals in the first frequency band and for coupling them to an output port of the customer interface unit;
• a second demodulator for receiving the second signals and for identifying, from the second signals, one of a plurality of frequency sub bands in a second frequency band in the broadband communication network for communicating the telephony signals to the headend;
• and
• a frequency agile modulator, responsive to the identified one of said plurality of frequency sub bands in the second frequency band, for generating modulated signals by modulating the telephony signals from the customer interface unit in the identified frequency subband, each of the telephony signals including in-phase (I) and quadrature (Q) signal components, the frequency agile modulator comprising:
• a filter for filtering the I and Q signal components to produce filtered I and Q signal components;
• an interpolation module for generating processed I and Q signal components by upsampling the filtered I and Q signal components;
• a plurality of channel modulators, each of the channel modulators responsive to a pair of the processed I and Q signal components for modulating one of a plurality of carrier signals selected in response to the identified one of the plurality of frequency subbands in the second frequency band with a selected one of the telephony signals to produce a complex modulated signal having a real signal component and an imaginary signal component;
• an adder module, responsive to the complex modulated signal generated by each of the channel modulators, for summing the real signal component of each channel modulator to produce a real resultant signal and for summing the imaginary signal component of each channel modulator to produce an imaginary resultant signal;
• a digital-to-analog converter (DAC) module for converting the real resultant signal and the imaginary resultant signal to analog signals, and
• a transmitter, responsive to the analog signals, for transmitting the modulated signals within the identified frequency subband of the second frequency band of the broadband communications network.