Method for broadcasting of digital data, notably for radio broadcasting at high throughput rate towards mobile receivers, with time frequency interlacing and analog synchronization
First Claim
1. A method for the broadcasting and receiving digital data consisting of a source of binary elements comprising the steps of:
- providing a plurality of orthogonal frequency carriers;
convolutively coding said source binary elements to form a series of data elements;
temporally interlacing said series of data elements by selectively delaying at least some of said data elements of the series, no two adjacent data elements in said series being delayed by the same amount;
grouping said temporally interlaced series of data elements in data symbols;
grouping said data symbols in frames of symbols, each frame of symbols beginning with a frame header;
inserting in said frame header a first analog synchronization symbol formed by an interval of silence, said interval of silence having the duration of a data symbol;
frequentially interlacing said data elements by selectively modulating said plurality of orthogonal frequency carriers with the data elements of data symbol, each of said data elements being associated with only one of said frequency carriers;
simultaneously broadcasting all of said modulated frequency carriers, the temporal and frequential interlacing effectively preventing any two adjacent data elements in said series of data elements from being broadcast successively in time on a same frequency carrierreceiving the broadcast modulated orthogonal frequency carriers;
detecting an envelope of said first analog synchronization symbol of the header in each of said frames;
setting off a time base for receiver synchronization upon detection of said envelope of said first analog synchronization symbol;
demodulating at least some of said frequency carriers of each of said data symbols to form demodulated data elements;
frequentially de-interlacing said demodulated data elements;
temporally de-interlacing said demodulated data elements; and
decoding said frequentially and temporally de-interlaced data elements.
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Abstract
A method for the diffusion of digital data designed to be received notably by mobile receivers moving in an urban environment, that is, in the presence of stray signals and jamming, and in conditions of multiple propagation (Rayleigh process) providing an optimized mode of setting up the frame structure of the broadcast signal, so as to derive the maximum benefit from the resistance of the system to pulsed stray signals and to jamming. The header of each frame has a first empty synchronization symbol and eventually a second, unmodulated wobbled signal forming a two-stage analog synchronization system. So, the recovery of synchronization is achieved in an analog way, without prior extraction of a clock signal at the binary level. The constitution of the sequence of the useful symbols in the frame results from temporal and sequential interlacing operations, combined to obtain an implicit de-interlacing at the receiver. The empty symbol may be further used for the extraction of the jamming affecting the transmission channel.
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Citations
13 Claims
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1. A method for the broadcasting and receiving digital data consisting of a source of binary elements comprising the steps of:
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providing a plurality of orthogonal frequency carriers; convolutively coding said source binary elements to form a series of data elements; temporally interlacing said series of data elements by selectively delaying at least some of said data elements of the series, no two adjacent data elements in said series being delayed by the same amount; grouping said temporally interlaced series of data elements in data symbols; grouping said data symbols in frames of symbols, each frame of symbols beginning with a frame header; inserting in said frame header a first analog synchronization symbol formed by an interval of silence, said interval of silence having the duration of a data symbol; frequentially interlacing said data elements by selectively modulating said plurality of orthogonal frequency carriers with the data elements of data symbol, each of said data elements being associated with only one of said frequency carriers; simultaneously broadcasting all of said modulated frequency carriers, the temporal and frequential interlacing effectively preventing any two adjacent data elements in said series of data elements from being broadcast successively in time on a same frequency carrier receiving the broadcast modulated orthogonal frequency carriers; detecting an envelope of said first analog synchronization symbol of the header in each of said frames; setting off a time base for receiver synchronization upon detection of said envelope of said first analog synchronization symbol; demodulating at least some of said frequency carriers of each of said data symbols to form demodulated data elements; frequentially de-interlacing said demodulated data elements; temporally de-interlacing said demodulated data elements; and decoding said frequentially and temporally de-interlaced data elements. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification