DVB-T Signal Detection via Time-Domain Correlation
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Solution Overview
Problem
Existing sensing algorithms for DVB-T and DVB-H signals are ineffective for all transmission modes, particularly at low signal-to-noise ratios, due to the distribution of lower-power pilots in the frequency domain, which complicates reliable detection in Cognitive Radio networks.
Innovation Solution
A method and system that correlate received RF signals with a time-domain reference sequence representing the frequency-domain pilots, using averaged signal samples and thresholds to detect DVB transmissions, improving detection performance across all transmission modes by reducing noise variance and maintaining robustness in various channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If frequency domain filtering is used to detect pilots, then detection is simple for ATSC signals with single pilot, but it is not feasible for DVB-T signals with distributed lower-power pilots
Solution Approach 1:
The patent inverts the detection approach by transitioning from frequency domain filtering to time domain correlation. Instead of filtering frequency components to find pilots, the method correlates the received signal with a known time-domain reference sequence representing the pilot pattern, making detection feasible for DVB-T signals with distributed pilots
Solution Approach 2:
The patent changes the detection parameter domain from frequency domain to time domain. By transforming the reference sequence to time domain and performing correlation there, the method adapts to detect DVB-T signals while maintaining the simplicity of reference-based detection
2Productivity
If existing sensing algorithms are used for DVB-T signals, then detection works for some transmission modes, but detection performance is unreliable across all transmission modes especially at low SNR
Solution Approach 1:
The patent performs preliminary averaging of signal samples before correlation with the reference sequence. This preprocessing step reduces noise variance in advance, improving the reliability of detection at low SNR values across all transmission modes
Solution Approach 2:
The method uses correlation results compared against thresholds to determine signal presence, providing a feedback mechanism that adapts to different transmission modes and channel conditions, ensuring reliable detection across varied scenarios
3Productivity
If CR devices operate in UHF band, then spectrum utilization improves, but interference to DTV reception occurs
Solution Approach 1:
The patent implements preliminary detection of DVB-T signals before CR devices transmit. By sensing the presence of primary transmissions using the correlation method and vacating the band when signals are detected, CR devices can utilize the UHF band efficiently while preventing harmful interference to DTV reception
Data Source
AI summary
A method and system is provided for detecting the presence of a DVB (digital video broadcasting) transmission. The method includes receiving an RF (radio frequency) signal in a selected channel (1101); creating signal samples from the received RF signal (1102); creating averaged samples from the signal samples, each averaged sample being an average of a predetermined number of signal samples that are separated by a minimum pilot pattern repetition period from one to the next signal sample (1103); correlating the averaged samples with a reference sequence (1104); and comparing a correlation result with a threshold correlation value (1105).