signals 34 ieee transactions on space electronics and telemetry vol set 9 march 1963 pp 1 8 in the delay lock loop fig2 the incoming input pseudo noise pn code modulated signal is provided to mixer circuits 10 and 12 and multiplied by a code known as an 34 early code 34 a timing signal whose pulses occur in time slightly in advance of the timing pulses of the signal being tracked and a tracking code signal known as a 34 late code 34 signal whose timing pulses occur slightly later in time than the time of occurrence of the pulses of the signal being tracked the early code and late code are formed in conventional digital code generating circuitry the output of the mixer 10 is provided to a first bandpass detector b 1 having a bandpass filter square law circuit and low pass filter so that an error signal representing the phase error between the incoming input signal and the 34 early 34 code is formed and provided to a summing circuit 14 at an input thereof in a like manner the product signal formed in the mixer 12 is provided to a second bandpass detector b 2 having a bandpass filter square law circuit and low pass filter for forming an error signal which is also provided to the summing circuit 14 the summing circuit.