Improved receiver synchronization for PN-MSK-modulated spread spectrum burst transmission systems

In spread spectrum burst transmission systems (SSBTS), receiver synchronization has to be carried out for each telegram arriving at the receiver. Especially when very high spreading factors are used, the signal processing complexity for this task is limited. Generally, it is advantageous to effect receiver synchronization by a preamble consisting of one or several, staggered spread spectrum waveforms which can be detected by digital matched filtering in the receiver. However, because of its spectral efficiency it is highly desirable to use PN-MSK as the spreading modulation in many applications. It is shown that due to the characteristics of PN-MSK, improved synchronization circuits are required when this modulation scheme is used for burst transmission. For a complex real-world spread spectrum receiver, an optimized synchronization circuit is proposed and its performance is compared to that of the conventional solution. The improved synchronization circuit does not significantly increase the signal processing complexity as compared to the conventional circuit, and thus is especially suited for spread spectrum burst transmission systems with high spreading factors.