Maxim Integrated Products explains the benefits of OFDM communications with an example of eight tones between 10 and 95 kHz, providing a usable channel bandwidth of 85 kHz. A single-carrier system would use two tones to transmit data in that bandwidth. In both cases, four data bits and four error-correction bits get sent, but OFDM would transmit all eight bits with a single symbol. FSK (frequency shift keying) would transmit the same data with four symbols. Because OFDM uses the spectrum more efficiently, it opens the channel for data and thus provides a higher data rate. The higher number of tones from OFDM also makes possible advanced encoding techniques unavailable with single-carrier approaches.