Broadcast Signal Detection Using Frequency Offset Evaluation
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Solution Overview
Problem
In all-digital digital radio broadcasting systems, the search for broadcast signals is time-consuming due to the absence of analog signals, which complicates the detection process.
Innovation Solution
A broadcast signal detecting method that involves receiving and evaluating broadcast signals at different frequencies, converting them to intermediate frequencies, checking frequency offsets, and demodulating data to determine if the signal is from a broadcasting station, thereby shortening the search time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a searching method is used wherein the broadcast signal is selected and outputted upon evaluation that an analog broadcast signal is included, then the detection process is simplified, but the search time becomes excessively long in all-digital systems
Solution Approach 1:
The patent performs preliminary actions by first evaluating reception quality metrics (SNR, signal strength) and frequency offset before attempting full signal detection and demodulation. This preliminary filtering eliminates obviously invalid frequencies early in the search process, reducing the overall search time without sacrificing detection accuracy.
Solution Approach 2:
The signal detection process is segmented into multiple stages: initial frequency scanning with quick quality evaluation, intermediate frequency offset checking, and final demodulation for confirmation. This segmentation allows the system to process frequencies in order of likelihood, stopping early when a valid signal is found or when all possibilities are exhausted, thereby reducing search time.
2Measurement precision
If the broadcast signal is evaluated by checking reception quality and frequency offset at multiple frequencies, then the accuracy of broadcast signal detection is improved, but the processing complexity increases
Solution Approach 1:
The patent applies partial action by performing complete demodulation and data verification only for frequencies that pass the initial quality and frequency offset checks. For most frequencies in the scanned range, only lightweight evaluation metrics are computed, reducing overall processing complexity while maintaining high detection accuracy for valid signals.
Solution Approach 2:
Different evaluation criteria are applied at different stages of the search process. Initial scanning uses simple SNR and signal strength thresholds, intermediate checking uses frequency offset validation, and final confirmation uses full demodulation. This local quality approach optimizes processing complexity by applying appropriate evaluation depth only where necessary.
Data Source
AI summary
If reception quality of a broadcast signal of a first frequency received by a tuner satisfies setting conditions, the frequency received by the tuner is changed from the first frequency to a second frequency. It is evaluated whether or not the amount of offset between a reference frequency and the frequency of the signal, which is generated by converting the broadcast signal of the second frequency received by the tuner into an intermediate frequency is within a predetermined range. If the offset between the reference frequency and the frequency of the intermediate frequency signal is within the predetermined range, the data included in the broadcast signal of the first frequency is acquired by a demodulating the broadcast signal of the first frequency. It is evaluated whether or not the broadcast signal of the first frequency is a broadcast signal of a broadcasting station based on the acquired data.