DSSS-Signal (Direct Sequence Spread Spectrum Signal) has the ability of anti-jamming and anti-interception

it is widely used in electronic countermeasures

satellite communications

measurement and data transmission. It is simplex to improve signal anti-interception by the method of fixed PN (Pseudo-Noise) code

code hopping and variable symbol period chaotic sequence. Therefore

we combine the strong-signal masking technology with direct sequence spread spectrum technology

and propose a waveform design method to enhance the signal covertness. The data of different security levels are modulated hierarchically to make strong-signal mask weak-signal

also the parameters of waveform are designed in the aspects of power and period to highlight the characteristics of strong-signal and hide the confidential signal. Simulations show that the designed signal waveform can resist conventional blind detection. Moreover

setting the waveform parameters reasonably can achieve demodulation loss less than 0.5 dB.