Methods and systems for rapid detection of digital radio signals

摘要

Systems and methods are disclosed for rapid detection of digital content within received radio frequency (RF) signals. The disclosed embodiments digitize received RF signals and apply a sliding window average to subsampled complex magnitudes for the digital samples to generate subsampled magnitude values. The subsampled magnitude values are then collected over a small number of symbols for the digital content, and the results are analyzed to determine whether or not digital content is present with the received signals. For example, multi-symbol histograms and magnitude ratios determined over multiple symbols can then be utilized to make the determination of whether digital content is present in the received signals. The resulting detection determination can be utilized further to control operations of systems utilizing the disclosed embodiments. The disclosed embodiments can be used, for example, to detect the presence of HD (High Definition) Radio digital content within broadcast channels.

主权项

1. A receiver system for detecting digital content in a radio frequency (RF) channel, comprising:
front-end circuitry configured to receive radio frequency (RF) signals and to output signals associated with a channel within the RF signals; analog-to-digital conversion (ADC) circuitry configured to receive the output signals and to output digital samples having a real component (I) and an imaginary component (Q); complex magnitude determination circuitry configured to receive the digital samples and to generate complex magnitudes for the digital samples; sliding window averaging filter circuitry configured to subsample the complex magnitudes for each of a plurality of symbols, to apply a sliding window average to the subsampled complex magnitudes to generate a plurality of averaged subsampled magnitude values for each symbol based upon subsampled complex magnitudes within sliding windows of subsampled complex magnitudes, and to output the averaged subsampled magnitude values for each symbol; and shape detection circuitry configured to determine if digital content is present within the channel having a digital content shaping function, the digital content shaping function being associated with digital content to be detected, the shape detection circuitry comprising:
buffer circuitry configured to store the averaged subsampled magnitude values for each symbol, each averaged subsampled magnitude value having an associated index value; anddetection circuitry configured to detect a minimum value within the stored averaged subsampled magnitude values for each symbol, to output an index value associated with the detected minimum value for each symbol, and to form an index count histogram based upon index values output for the plurality of symbols;wherein the index count histogram includes count values associated with the index values output for the plurality of symbols; andwherein the shape detection circuitry is further configured to use the count values within the index count histogram to determine if digital content is present within the channel having the digital content shaping function; wherein the digital content is included within OFDM (orthogonal frequency division multiplexed) symbols transmitted within the channel, and wherein the digital content shaping function comprises a pulse shaping function applied to each OFDM symbol.