C/N performance of broadband two-way transmission of RF signals over transmission mediums with limited bandwidth

An RF block conversion apparatus for processing an input RF signal formed by combining n RF signals each of said RF signals being within a frequency band distinct from a frequency band of all other RF signals that were combined to form said input RF signal, said apparatus comprising:

• a signal input for receiving said input signal,
• n bandpass filters each having an input connected to the signal input and an output, all bandpass filters having a bandwidth such that the bandwidth of each filter corresponds to a bandwidth of one of the signals from which the input signal was formed,
• n−1 mixers, each mixer connected to an output of one of the n bandpass filters, such that there in one bandpass filter not connected to a mixer, wherein each of the bandpass filters has a bandwidth that does not overlap a bandwidth of any of the other bandpass filters;
• and
• means for generating n−1 oscillator signals, each of a different RF frequency and connected to the mixers such that each mixer receives a different one of the n−1 oscillator signals and converts a signal from the bandpass filter to which the mixer is connected.

A broadband two-way communication system comprising:

• a headend;
• at least one service area node;
• a two-way transmission system connecting said at least one service area node with said headend for simultaneous two-way communication, said service area node comprising n branches each carrying a shared bandwidth RF subscriber signal and an up conversion system frequency stacking all of said shared bandwidth RF subscriber signals into a frequency stacking all of said shared bandwidth RF subscriber signal in which said n shared bandwidth RF subscriber signals are incorporated into n separate frequency bands, said frequency stacked RF return signal being transmitted over said two-way transmission system to said headend, said up conversion system including up converters using local oscillator signals to generate said separate frequency bands, and up converter local oscillator means generating said local oscillator signals for up conversion from a base local oscillator signal transmitted from said headend over said two-way transmission system, said headend having means generating a broadband downstream signal which is transmitted over said two-way transmission system to said at least one service area node which distributes said broadband RF downstream signal over each of said n branches, said headend also having a down conversion system for extracting said shared bandwidth RF subscriber signals from said frequency stacked RF return signals as separate signals, said down conversion system comprising bandpass filter means extracting each of said n separate frequency bands from said frequency stacked RF return signal, down converters using n−1 local oscillator signals to extract said shared bandwidth RF subscriber signals from said separate frequency bands, down converter local oscillator means generating said local oscillator signals for down conversion from said base local oscillator signal;
• and
• oscillator means, located at said headend, for generating said base local oscillator signal.

RF block conversion means for processing n shared band RF signals, said apparatus comprising:

• means for receiving a signal of a selected RF frequency for use as a base local oscillator signal;
• means for generating from said base local oscillator signal, n−1 local oscillator signals, each of a different RF frequency;
• n−1 mixers to each of which one of said n−1 local oscillator signals is applied to convert between one of said shared band RF signals and n−1 different frequency bands;
• and
• n bandpass filters including n−1 bandpass filters for each of said n−1 different frequency bands converted to said mixer means and one bandpass filter for said shared band, all n of said bandpass filters being connected to a common node at which a frequency stacked RF signal having said n RF signals stacked in n frequency bands is present.

A method of broadband two-way communication between a headend and a large number of subscribers comprising:

• generating a broadband RF downstream signal at the headend;
• transmitting said broadband RF downstream signal over a two-way transmission system to a number of service area nodes;
• distributing said broadband RF downstream signal from each service area node to associated groups of subscribers over a plurality of branches between the service area node and said groups of subscribers;
• sending shared bandwidth RF subscriber signals from each group of subscribers back to the associated service area node over said branches;
• frequency stacking said shared bandwidth RF subscriber signals from said plurality of branches in each service are node into a stacked frequency RF return signal using a common base local oscillator signal transmitted from said headend to each of said local nodes via said two-way transmission system;
• transmitting said stacked frequency RF return signals from each service area node to said headend;
• frequency destacking said stacked frequency RF return signals in said headend to extract said plurality of shared bandwidth RF subscriber signals;
• generating said base local oscillator signal;
• and
• distributing said base local oscillator signal to said headend for said frequency destacking and to each of said plurality of subscriber units for said frequency stacking of said shared bandwidth RF subscriber signals.

An RF block conversion apparatus for processing n shared band RF signals in a broadband two-way communication system, said apparatus comprising:

• n signal inputs, one for each of the n shared band RF signals,
• n−1 mixers, each mixer attached to one of the n signal inputs,
• at least one generator for generating n−1 oscillator signals, each of a different RF frequency and connected to the mixers such that each mixer receives a different one of the n−1 oscillator signals and converts one of said shared band RF signals;
• and
• n bandpass filters each having an input and an output, the input of one bandpass filter connected directly to a signal input and each of the other of said bandpass filters having their input connected to one of the mixers such that each mixer is connected to one of the bandpass filters, the outputs of all bandpass filters being connected to a common node and not connected to a combiner or splitter wherein each of the bandpass filters has a bandwidth that does not overlap a bandwidth of any of the other bandpass filters.

An RF block conversion apparatus for processing four shared band RF signals in a broadband two-way communication system, said apparatus comprising:

• four signal inputs, one for each of the four shared band RF signals,
• three mixers, each mixer attached to one of the four signal inputs,
• at least one generator generating three oscillator signals, each of a different RF frequency and connected to the mixers such that each mixer receives a different one of the three oscillator signals and converts one of said shared band RF signals;
• and
• four bandpass filters each having an input and an output, the input of one bandpass filter connected directly to a signal input and each of the other of said bandpass filters having their input connected to one of the mixers such that each mixer is connected to one of the bandpass filters, the outputs of all bandpass filters being connected to a common node and not connected to a combiner or splitter wherein each of the bandpass filters has a bandwidth that does not overlap a bandwidth of any of the other bandpass filters.