Design and performance evaluation of new signal waveform in eLoran system

As a backup system of satellite navigation system, the enhanced Loran navigation system is a vital development strategy for national PNT (Positioning, Navigation, Timing). At present, the signal of eLoran are vulnerable to cross interference and sky-wave interference, and the rate of transmitting data is low. Therefore we proposed two waveform improvement methods (attenuation-function-method and symmetric-waveform-method) and evaluated the performance of them based on standard Loran signal system. Experimental results show that the two methods can effectively shorten the duration of the waveform, accelerate the decline of the waveform, and reduce the signal transmitting power. The symmetrical-waveform-method can greatly reduce the duration of waveform, but this method will significantly change the spectrum characteristics of the original signal waveform. By contrast, the attenuation-function-method can ensure the spectrum performance of the signal to the greatest extent. Through comprehensive analysis, we think that the new waveform can effectively utilize time domain resources, which can spare time for extra signal transmitting and consequently raise the efficiency of data modulation.