A data transmission may include a physical layer header encoded with transmission parameters to decode a corresponding data frame. The encoding may include forward error correction (FEC) encoding.
At a receiver, the physical layer header may be decoded to identify transmission parameters of the corresponding data frame. The data frame may then be processed in accordance with the transmission parameters. The transmission parameters may include a modulation sequence and/or an encoding rate, and the processing of the data frame may include decoding, such as with a low-density parity check code (LDPC) decoder.
Environmental conditions may reduce an ability of a receiver to decode a physical layer header. For example, environmental conditions may reduce a signal-to-noise ratio (SNR), in some situations to where signal power is lower than noise power. Receiver equipment may also cause a relatively large frequency offset in a received signal. A satellite based transmissions of a digital video broadcast signal, for example, may be received with a SNR of approximately −2.5 dB, signal power being lower than the noise power, and with a frequency offset of approximately 5 MHz.
In the drawings, the leftmost digit(s) of a reference number identifies the drawing in which the reference number first appears.