Digital Modulator Pulse Shaping for Cable TV Bandwidth
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Solution Overview
Problem
Existing cable TV networks face difficulties in efficiently reconfiguring analog and digital signal interconnections, limiting the flexible use of bandwidth for Video on Demand services due to hardwired modulators that require manual reconfiguration and restrict switching between frequency bands.
Innovation Solution
A method and apparatus for shaping pulses in a communications system, involving generating and combining overlapping pulses, and modulating input signals using a numerically controlled oscillator and QAM modulation, allowing for efficient use of bandwidth and flexible switching between frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hardwired modulators are used in cable TV networks, then signal transmission stability is improved, but system reconfiguration flexibility deteriorates
Solution Approach 1:
The patent replaces hardwired mechanical interconnections with software-configurable digital signal processing. The modulator architecture uses programmable logic and digital signal processors that can be reconfigured through software, eliminating the need for physical rewiring while maintaining signal transmission stability. This allows dynamic allocation of frequency bands and modulation schemes based on service requirements.
Solution Approach 2:
The invention implements dynamic reconfiguration capabilities where the modulator can adapt its parameters in real-time. The system uses configurable pulse shaping filters and modulation schemes that can be adjusted through control signals, enabling the same hardware to serve multiple functions and frequency bands without manual intervention.
2Device complexity
If manual reconfiguration is required for modulators, then system complexity is reduced, but operational efficiency deteriorates
Solution Approach 1:
The patent implements self-service automation where the modulator system can reconfigure itself based on incoming service requests and network conditions. The control system automatically adjusts modulation parameters, frequency allocations, and resource distribution without requiring technician intervention, thereby improving operational efficiency while maintaining manageable system complexity through standardized protocols.
3Object-affected harmful factors
If frequency bands are fixed for specific services, then interference between services is reduced, but bandwidth utilization efficiency deteriorates
Solution Approach 1:
The invention implements dynamic frequency allocation where service assignments and frequency band allocations can change in real-time based on network conditions and service requirements. The system uses configurable pulse shaping and filtering to minimize interference between dynamically allocated channels, allowing efficient packing of multiple services within the available spectrum while maintaining signal integrity.
Solution Approach 2:
The patent utilizes adjustable modulation parameters including pulse shaping filter characteristics, symbol rates, and frequency offsets that can be optimized for each service allocation. These parameters are dynamically adjusted to maximize spectral efficiency while maintaining adequate isolation between adjacent channels, thereby reducing interference without sacrificing bandwidth utilization.
Data Source
AI summary
The present application describes a method and filter for shaping a series of pulses spaced in time for subsequent transmission in a communications system, each of the pulses having a magnitude comprising the steps of providing a generic shaped pulse, for each pulse in the series, generating a shaped pulse by scaling the generic shaped pulse by an amount proportional to the magnitude, wherein at least a portion of each generated pulse overlaps in time with at least a portion of at least one subsequent generated pulse, and combining the overlapping portions of the generated pulses.The present application also describes a method and apparatus for modulating an input signal comprised of an ordered series of samples separated by a substantially constant period T comprising the steps of providing a carrier signal, the carrier signal comprised of a series of samples separated by a substantially constant period T, wherein one of the carrier samples corresponds to each of the input signal samples, selecting a plurality of N successive samples from the series of input signal samples, the series of samples having an input order, for each of the N selected samples in parallel, multiplying the selected sample by the corresponding carrier sample and recombining the N multiplied samples while maintaining the input order.