Olivia MFSK

Olivia MFSK is an amateur radioteletype protocol designed to work in difficult (low signal-to-noise ratio plus multipath propagation) conditions on shortwave bands. The signal can still be properly copied when it is buried 10 dB below the noise floor (i.e. when the amplitude of the noise is just over 3 times that of the signal). It is commonly used by amateur radio operators to reliably transmit ASCII characters over noisy channels using the high frequency (3-30MHz) spectrum.

Olivia modes are commonly referred to as Olivia X / Y (or, alternatively, Olivia Y / X ), where X refers to the number of different audio tones transmitted and Y refers to the bandwidth in hertz over which these signals are spread. Examples of common Olivia modes are 16/500, 32/1000 and 8/250.