In modern communication and navigation systems the method of direct spectrum spreading is widely used. This method assumes that before modulation the information sequence of bits is multiplied by a PN sequence. Classically, the PN sequence pulses are rectangular, so they are easiest to generate. However the signal spectrum width should be minimized, maintaining the benefits of spread spectrum signals. For this purpose we can move from rectangular pulses to quasi-harmonic pulses. At the same time when you change the pulse shape, it is necessary to maintain high correlation properties of PN sequence. The present study focuses on the changes of the autocorrelation functions of noise-like signals when quasi-harmonic pulses are used under the conditions of spectrum limitation.