circuit 34 produces as its output is representative of the said radial error r the frequency of repetition of the pulses 36 is representative of the error angle u03b8 e the pulses 36 are fed to a pulse decoding circuit 37 the output from the roll angle circuit 35 provides information as to the roll angle u03b8 b of the missile body relative to space it does not identify a unique roll angle but rather one of two roll angles spaced apart by 180 u00b0 the output of the roll angle circuit 35 is fed to a body angle logic circuit 38 the roll angle circuit 35 also generates an automatic gain control agc signal which is fed to the amplifiers 32 and 33 where it serves to ensure their linear operation so long as the amplification is linear the body roll angle u03b8 b is determinable by comparison of the magnitude of the outputs of the amplifiers 32 and 33 the circuits 37 and 38 are components of digital logic beam riding guidance circuitry typically of complexity 4 op amps which examines the error angle u03b8 e and determines what angle u03b8 g of the nose section 11 of the missile in space is needed to rectify the error the desired space angle of the nose section 11 is achieved by securing a desired angle of the nose section 11 u03b8 dnb relative to the body of the missile 11 having regard to the space roll angle.