Apparatus for transmitting broadcast signals, apparatus for receiving broadcast signals, method for transmitting broadcast signals and method for receiving broadcast signals

A transmitting apparatus for transmitting a broadcast signal, the apparatus comprising:

• an input formatting module formatting input data into at least one DP (data pipe);
• a bit interleaved coding and modulation (BICM) module encoding data of the DP;
• a frame building module generating one or more signal frames by mapping the encoded DP data;
• and
• an OFDM (orthogonal frequency division multiplexing) generation module modulating data of the generated signal frame by an OFDM scheme and transmitting a broadcast signal including the modulated data of the signal frame,
• wherein the signal frame includes a preamble, a PLS (Physical Layer Signaling), and the data of the DP, the preamble being located at a beginning of the signal frame and the preamble and the PLS carrying signaling data for the signal frame,
• wherein the preamble includes EAC (Emergency Alert Channel) flag information indicating whether there exists an EAS (Emergency Alert System) message in the signal frame, and
• wherein when the EAC flag information indicates that there exists the EAS message in the current signal frame, the PLS further includes EAC length information and when the EAC flag information indicates that there doesn't exist the EAS message in the current signal frame, the PLS further includes control information related to EAS message transmission, and
• wherein the control information includes at least one of an EAC code and an EAC counter and a value of the EAC counter is a down counter which indicates a number of signal frames remaining until a next signal frame including the EAS message is received.

A receiving apparatus for receiving a broadcast signal, the apparatus comprising:

• a synchronization and demodulation block;
• a frame parsing block parsing a signal frame output from the synchronization and demodulation block;
• a demapping and decoding module;
• and
• an output processor module,
• wherein the signal frame includes a preamble, a PLS (Physical Layer Signaling), and the data of the DR, the preamble being located at a beginning of the signal frame and the preamble and the PLS carrying signaling data for the signal frame,
• wherein the preamble includes EAC (Emergency Alert Channel) flag information indicating whether there exists an EAS message in the signal frame, and
• wherein when the EAC flag information indicates that there exists the EAS message in the current signal frame, the PLS further includes EAC length information and
• when the EAC flag information indicates that there doesn't exist the EAS message in the current signal frame, the PLS further includes control information related to EAS message transmission,
• wherein the control information includes at least one of an EAC code and an EAC counter and a value of the EAC counter is a down counter which indicates a number of signal frames remaining until a next signal frame including the EAS message is received.