Technique for providing secondary data in a single-frequency network
A technique for providing secondary data in a single frequency network (SFN) provides a first forward error correcting (FEC) decoder for decoding a received coded orthogonal frequency division multiplex (COFDM) signal. A second FEC decoder is also provided for decoding a received COFDM signal. When the received COFDM signal includes valid primary data, the first FEC decoder is utilized to decode the received COFDM signal to provide general information, i.e., music, sports, etc. When a received COFDM signal includes valid secondary data, the second FEC decoder is utilized to decode the received COFDM signal to provide regional information, e.g., emergency broadcasting information. The received COFDM signal includes one or more defined COFDM symbols inserted by a transmitter of the COFDM signal to indicate the valid secondary data and the invalid primary data.
1. A satellite digital audio radio (SDAR) receiver, comprising:
a tuner including an input for receiving a coded orthogonal frequency division multiplexing (COFDM) signal and an output;
an orthogonal frequency division multiplexing (OFDM) demodulator including an input and an output, wherein the input of the OFDM demodulator is coupled to the output of the tuner;
a router including an input, a first output and a second output, wherein the input of the router is coupled to the output of the OFDM demodulator;
a first forward error correcting (FEC) decoder including an input coupled to the first output of the router and an output, wherein the output of the first FEC decoder is coupled to a first input of a source decoder, and wherein the first FEC decoder decodes the received COFDM signal to provide general information to the source decoder when the received COFDM signal includes valid primary data; and
a second FEC decoder including an input coupled to the second output of the router, wherein the output of the second FEC decoder is coupled to a second input of the source decoder, and wherein the second FEC decoder decodes the received COFDM signal to provide regional information to the source decoder when the received COFDM signal includes valid secondary data, and invalid primary data where the received COFDM signal includes one or more defined COFDM symbols inserted by a transmitter of the COFDM signal to indicate the valid secondary data and the invalid primary data.
2. The receiver of claim 1 , wherein the primary data and the secondary data are assigned different interleavers.
3. The receiver of claim 2 , wherein the interleaver for the primary data includes a plurality of COFDM symbols.
4. The receiver of claim 3 , wherein the interleaver for the secondary data includes a single COFDM symbol.
5. The receiver of claim 1 , wherein the COFDM symbol includes a sub-modulation.