DVB-T2 Signal Discovery Using Frequency-Shifted Guard Interval
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Solution Overview
Problem
Current DVB-T2 signal discovery processes are slow and inefficient, particularly when scanning for RF channels and determining signal formats, which can lead to increased scan times and data capacity reduction, especially with the introduction of additional broadcaster options and signal types like DVB-T and analogue TV.
Innovation Solution
The implementation of a Unique Signal-Discovery Symbol (USDS) with a frequency shift in the guard interval, allowing for rapid identification of DVB-T2 signals, coarse frequency offset determination, and frame start indication, while minimizing interference and data capacity loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional DVB-T2 signal discovery processes are used, then signal format determination can be achieved, but scan times are increased and data capacity is reduced
Solution Approach 1:
The signal structure is segmented into distinct parts: a frequency-shifted guard interval portion and a data portion. The frequency-shifted guard interval serves as a unique identifier for rapid signal discovery, while the data portion carries the actual information. This segmentation allows the system to quickly identify DVB-T2 signals without processing the entire data stream, thus reducing scan time while preserving data capacity.
Solution Approach 2:
A specific local property (frequency shift) is applied to the guard interval portion of the signal to create a distinctive characteristic that enables rapid identification. This localized modification does not affect the overall data capacity since it only alters the guard interval, which is otherwise redundant information used for synchronization and equalization purposes.
2Adaptability or versatility
If additional broadcaster options and signal types are added, then signal versatility is improved, but scan time increases
Solution Approach 1:
The frequency-shifted guard interval is placed at the beginning of the signal frame, performing the preliminary function of signal identification before any data processing occurs. This allows the receiver to quickly determine whether a signal is present and what format it uses, enabling rapid switching between different signal types (DVB-T, DVB-T2, analogue TV) without extensive scanning.
Solution Approach 2:
The system uses parameter changes (frequency shift in the guard interval) to create a distinctive marker that can be detected across different signal formats. This parameter modification provides a universal identification mechanism that works regardless of the specific broadcaster options or signal types being used, maintaining versatility while enabling fast discovery.
Data Source
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AI summary
A system for determining the presence of, and information about, a DVB-T2 signal comprises means for providing a symbol with an active portion, providing a repetition portion and frequency shifting the repetition portion with respect to the active portion at a transmitter. At a receiver, the signal is multiplied by a complex conjugate of a delayed version of the signal to recover the symbol. The symbol may be referred to as a unique signal discovery symbol.