return to bias (RB)

RB encoding, Return to Bias (RB) is an encoding used in tape drives where the magnetic tape is preset to one polarity - "1" or "0".

If the pre- polarization is "0", then when a digital "1" is received, the magnetic particles are polarized in the opposite direction, towards the "1". After each "1" value, the magnetic particles return to the preset polarity. With the return-to- bias method, there is no possibility of clock recovery. It can only use an external clock signal to read out the 0 values stored on the magnetic tape.