Power Spectrum Channel Detection for Fast TV Service Scans
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Solution Overview
Problem
Conventional digital television receivers require lengthy service scans to identify available channels, especially in environments without prior knowledge of channel information or a defined frequency grid, leading to slow scanning times, particularly for satellite television.
Innovation Solution
A method involving the acquisition and analysis of a power spectrum to identify candidate channels by their centre frequency, allowing for rapid service information extraction and storage, utilizing a multi-channel receiver system with spectrum identifier, analysis, and controller modules to process and tune to candidate channels in parallel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sequential scanning is used to identify all available channels, then complete channel information is obtained, but the scanning time becomes excessively long (tens of minutes to hours)
Solution Approach 1:
The patent replaces the mechanical sequential tuning process with spectral analysis using Fast Fourier Transform (FFT). Instead of mechanically tuning through frequencies one by one, the system captures the entire signal band and performs spectral analysis to identify channel frequencies simultaneously, dramatically reducing scan time while maintaining complete channel detection
Solution Approach 2:
The patent performs preliminary spectral analysis of the entire signal band before individual channel processing. By first identifying all channel frequencies through power spectrum analysis, the system prepares a list of candidate channels that can then be processed efficiently, avoiding the need for time-consuming sequential scanning of all frequencies
2Loss of information
If the receiver scans the entire spectrum to locate channels without prior information, then all channels are found, but the process is extremely slow
Solution Approach 1:
The patent replaces the time-consuming mechanical spectrum scanning process with digital spectral analysis. The entire signal band is captured and transformed into the frequency domain using FFT, allowing simultaneous identification of all channel frequencies in a fraction of the time required for sequential scanning
Solution Approach 2:
The patent transitions from the time domain (sequential frequency tuning) to the frequency domain (spectral analysis). By viewing the signal spectrum all at once rather than tuning through frequencies sequentially, the system identifies all channel locations simultaneously, converting a time-intensive process into a rapid computational operation
3Measurement precision
If small stepsize is used in frequency scanning to ensure all channels are identified, then detection accuracy is improved, but scanning time increases significantly
Solution Approach 1:
The patent replaces incremental frequency tuning with fixed-step scanning with spectral analysis. The FFT-based approach provides inherent frequency resolution without requiring small tuning steps, as the spectral transform naturally identifies frequency components at the resolution determined by the analysis parameters, not by incremental tuning size
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces service scan time by quickly identifying channels from a power spectrum, eliminating the need for a full frequency scan, and is applicable to various transmission mediums including terrestrial, satellite, and cable broadcasts.
Implementation Method 1
a spectrum identifier module configured to compute a power spectrum of an input signal
Data Source
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AI summary
A method of performing a service scan for available channels across a bandwidth of an input signal, the method comprising the steps of: acquiring (401) a power spectrum of the input signal bandwidth; analysing (402) the power spectrum to identify a list of candidate channels, each candidate channel being identified by at least a centre frequency; processing (404, 405) each of the candidate channels in a receiver unit (205, 305) to extract (405) service information, if present, relating to the candidate channel; and storing (406) the service information for the channel in a memory (204, 304).