What does EFM mean in ELECTRONICS

Eight to Fourteen Modulation, or EFM, is an encoding method used in compact disc (CD) technology. It involves converting digital data into a special type of format that can be more efficiently stored on the disc surface.

In the EFM process, the digital audio signal is transformed from an 8 bit word into a series of 14 bit words, which are then encoded onto the CD's pits and lands. Each 14 bit word encodes up to eleven ones and zeros from the 8 bit source word along with additional error correction bits for greater reliability of storage on the CD.

Pits and lands refer to the physical marks that are inscribed onto a CD's surface by laser during its production process. Pits are small indentations which correspond to zeros in the encoded data while lands are flat portions corresponding to ones in the data.

Yes, compared to conventional linear blocks codes such as NRZ it provides better protection against errors due to scratches on discs or dirt contamination since each 14 bit word includes information not present in its original 8 bit source word.