Abstract: A method of channel processing is provided wherein multiple reduced-bandwidth “processing blocks” may be combined at RF to allow for the continuous and flexible placement of multiple-channels across the full or partial CATV output band. Each reduced-bandwidth processing block is associated with a fixed-frequency upconversion. In order to allow for continuous agile channel placement, the processing blocks overlap one another in frequency at RF. In the case where it is not necessary that the full CATV band be available to the combined output, the number of required processing blocks and upconversion paths is reduced and individual processing blocks and upconversion paths may be used to cover multiple non-contiguous frequency bands.

Abstract: A method of channel-to-port assignment is described where the distribution of channels is performed in the digital domain of the CATV/QAM upconverter/modulator. This channel distribution allows for the possibility of simple failover, power combining of multiple outputs, and a fine granularity of channel to port mapping, QAM or analog channel, in a multi-port device.

Abstract: A distortion-cancellation method for analog CATV or QAM transmission over cable is provided wherein a single feedback path from the output of a multiple-channel multiple-port upconverter/modulator is down-converted and used to reduce or cancel undesirable noise components including LO leakage, spurious, and modulated noise. The method allows for real-time monitoring, tuning, or control of the CATV/QAM output and of interfering signals and aging effects as compared to a desired performance metric.

Abstract: A method of channel processing is provided wherein multiple reduced-bandwidth “processing blocks” may be combined at RF to allow for the continuous and flexible placement of multiple-channels across the full or partial CATV output band. Each reduced-bandwidth processing block is associated with a fixed-frequency upconversion. In order to allow for continuous agile channel placement, the processing blocks overlap one another in frequency at RF. In the case where it is not necessary that the full CATV band be available to the output, the number of required processing blocks and upconversion chains is reduced and individual processing blocks and upconversion chains may be used to cover multiple non-contiguous frequency bands.

Abstract: A distortion-cancellation method for analog CATV or QAM transmission over cable is provided wherein a single feedback path from the output of a multiple-channel multiple-port upconverter/modulator is down-converted and used to reduce or cancel undesirable noise components including LO leakage, spurious, and modulated noise. The method allows for real-time monitoring, tuning, or control of the CATV/QAM output and of interfering signals and aging effects as compared to a desired performance metric.

Abstract: A method of channel-to-port assignment is described where the distribution of channels is performed in the digital domain of the CATV/QAM upconverter/modulator. This channel distribution allows for the possibility of simple failover, power combining of multiple outputs, and a fine granularity of channel to port mapping, QAM or analog channel, in a multi-port device.

Abstract: Direct digital QAM modulation at an RF frequency is obtained from digitally synthesized RF signals which are generated for use as the two vectors. The two vectors are individually controlled in phase and summed to provide a combined phase and amplitude modulation that forms the modulated signal. The synthesized RF signal is generated from a higher reference frequency using a variable pulse stretching technique implemented with programmable delay lines. The amount of the pulse stretch in each cycle is controlled by a phase increment value. Pulse stretching can be extended beyond one cycle by pulse swallowing, allowing the generation of an RF signal from DC up to and including the input reference frequency. Phase modulation is added by digital control of the pulse stretching according to the phase modulation data bits.

Abstract: A method to improve the frequency resolution and phase noise of a synthesized RF signal results in superior instantaneous frequency change and phase modulation capability, wide frequency set ability, and suitability for implementation in a digital ASIC. The RF signal synthesis is achieved from a higher reference frequency clock signal using a variable pulse stretching technique. The amount of the pulse stretch in each cycle is set by a phase increment value and is implemented using programmable delay lines. Pulse stretching can be extended beyond one cycle by pulse swallowing, allowing the generation of an RF signal with frequencies from DC up to the input reference frequency. Phase modulation is incorporated by digital control of the phase stretching with the phase modulation bits.

Abstract: The present invention provides a method to improve the frequency resolution and phase noise of a synthesized RF signal. It also results in the superior characteristics of instantaneous frequency changeability, wide frequency setting ability, and fully digital ASIC implementation ability. The synthesized RF signal is generated from a higher reference frequency using a variable pulse stretching technique. The amount of the pulse stretch in each cycle is controlled by a phase increment value and is implemented using programmable delay lines. Pulse stretching is extended beyond one cycle by pulse swallowing, allowing the generation of an RF signal from DC up to the input reference clock signal frequency.

Abstract: The present invention provides a means to implement amplitude and phase modulation digitally and directly at an RF frequency that benefits from high output power without the use of amplifiers. This is accomplished by the combination of two varying amplitude and phase vectors. A reference oscillator produces a carrier signal, which is supplied to two digital delay lines composed of a sequence of delay banks. The delay lines are controlled by lookup tables that are updated by the vector control circuit, used to determine the delay of each digital delay line. The output of each delay line is multiplexed to a switching bank which is also controlled by the vector control circuit. The output of the switching bank, in combination with a summer, is used to produce discrete amplitude adjustment of the vector.

Abstract: The present invention provides a means to implement amplitude and phase modulation digitally and directly at an RF frequency that benefits from high output power using non-linear amplifiers. This is accomplished by the combination of two constant amplitude phase varying vectors. A reference oscillator produces a carrier signal, which is supplied to two digital delay lines composed of a sequence of delay banks. The delay lines are controlled by lookup tables that are updated by the vector control circuit used to determine the delay of each digital delay line. The delay of the lines are set in such a way as to produce two vectors with the desired phase shift that, when summed together, produce a vector with the desired phase and amplitude characteristics.

Abstract: The present invention provides a means to implement amplitude and phase modulation digitally and directly at an RF frequency that benefits from high output power using non-linear amplifiers. This is accomplished by the combination of two constant amplitude phase varying vectors. A reference oscillator produces a carrier signal, which is supplied to two digital delay lines composed of a sequence of delay banks. The delay lines are controlled by lookup tables that are updated by the vector control circuit used to determine the delay of each digital delay line. The delay of the lines are set in such a way as to produce two vectors with the desired phase shift that, when summed together, produce a vector with the desired phase and amplitude characteristics.

Abstract: The present invention provides a means to implement amplitude and phase modulation digitally and directly at an RF frequency that benefits from high output power without the use of amplifiers. This is accomplished by the combination of two varying amplitude and phase vectors. A reference oscillator produces a carrier signal, which is supplied to two digital delay lines composed of a sequence of delay banks. The delay lines are controlled by lookup tables that are updated by the vector control circuit, used to determine the delay of each digital delay line. The output of each delay line is multiplexed to a switching bank which is also controlled by the vector control circuit. The output of the switching bank, in combination with a summer, is used to produce discrete amplitude adjustment of the vector.

Abstract: A method to implement direct digital QAM modulation at an RF frequency results in the superior characteristics of high output power using non-linear amplifiers, high frequency resolution, low phase noise, instantaneous frequency change capability, wide frequency setting ability, and suitability for full implementation in a digital ASIC. Two digitally synthesized RF signals are generated for use as the two vectors. The two vectors are individually controlled in phase and summed to provide a combined phase and amplitude modulation that forms the modulated signal. The synthesized RF signal is generated from a higher reference frequency using a variable pulse stretching technique implemented with programmable delay lines. The amount of the pulse stretch in each cycle is controlled by a phase increment value. Pulse stretching can be extended beyond one cycle by pulse swallowing, allowing the generation of an RF signal from DC up to and including the input reference frequency.

Abstract: A method to improve the frequency resolution and phase noise of a synthesized RF signal results in superior instantaneous frequency change and phase modulation capability, wide frequency set ability, and suitability for implementation in a digital ASIC. The RF signal synthesis is achieved from a higher reference frequency clock signal using a variable pulse stretching technique. The amount of the pulse stretch in each cycle is set by a phase increment value and is implemented using programmable delay lines. Pulse stretching can be extended beyond one cycle by pulse swallowing, allowing the generation of an RF signal with frequencies from DC up to the input reference frequency. Phase modulation is incorporated by digital control of the phase stretching with the phase modulation bits.

Abstract: The present invention provides a method to improve the frequency resolution and phase noise of a synthesized RF signal. It also results in the superior characteristics of instantaneous frequency changeability, wide frequency setting ability, and fully digital ASIC implementation ability. The synthesized RF signal is generated from a higher reference frequency using a variable pulse stretching technique. The amount of the pulse stretch in each cycle is controlled by a phase increment value and is implemented using programmable delay lines. Pulse stretching is extended beyond one cycle by pulse swallowing, allowing the generation of an RF signal from DC up to the input reference clock signal frequency.

Abstract: The present inventions provide methods and systems for optimizing the power consumption of a power amplifier used to amplify a QAM modulated signal by dynamically adjusting its compression point. The compression point is adjusted based upon the instantaneous peak value of the base band QAM signal.

Abstract: The present inventions provide methods and systems for reducing the peak to average power ratio of a multi-channel block of QAM signals. Reducing the peak to average power ratio of a signal ensures that amplifiers and transmitters are not saturated, causing loss of data, and reducing spatter to adjacent channels. Further, reducing peak to average power ratios reduces the consumption of power during transmission. The reduction is obtained by providing a symbol delay on one or more of the QAM signals prior to the signals being summed where the delay is computed such that peak QAM power transitions in the QAM signals statistically do not align in time. The delay is arranged according to the equation: the additional delay for each QAM signal is equal to the symbol rate of the QAM signals divided by the number of QAM signals in summation.

Abstract: A receiver for tracking a carrier suppressed phase-shifted input signal comprises a phase-locked loop circuit for receiving the input signal and having a variable frequency oscillator responsive to a control signal for oscillating at a frequency corresponding to an intermediate frequency and a frequency difference detector for producing an output signal indicative of the frequency difference between the frequency of the input signal and the intermediate frequency, a feedback loop network having a narrow-band path and a wide-band path and being responsive to the detector output signal for producing the control signal and applying the control signal to the oscillator through one of the paths whereby to change the intermediate frequency of the oscillator in response to the control signal, a quality detector responsive to the detector output signal for producing a signal corresponding to the bit error rate of the input signal; and selection means responsive to the bit error rate signal for causing the control sig