Abstract: This paper describes a class of offset carrier modulations for Direct Sequence-Spreal Spectrum (DS- SS) called Harmonic Offset Carrier (HOC) modulations. The spread spectrum waveform of HOC signal is composed of spreading code modulated by harmonic subcarriers. The auto-correlation function of HOC is equal to the envelope multiplied by harmonic factors. The first peak of the auto-correlation function is narrow, and its width is equal to reciprocal of spanned bandwidth of the signal. The closed form auto-correlation function of HOC modulation is given in this paper. This paper indicates that a Binary Offset Carrier (BOC) modulation could be write as a HOC modulation. HOC signal could be disjoined, and each subcarrier could implement in difference time. HOC signal could achieves high performance of anti-jamming, high resolution of time of arrival measurements, and high performance in multiple path environments. HOC signal synthesized in this paper presents a method how to reduce peak power to average power ratio. In final part of this paper, the character of extra spanned bandwidth HOC modulation is discussed.