Advantages of Wideband Modulation in Short MF-HF Communication Links.

In short communication links in the MF and HF bands, ionospherically reflected signals can interfere with desired ground-wave signals to degrade the performance of a conventional narrowband digital communication system, in which the pulse durations equal the reciprocal of the pulse recurrence rate. An alternate wideband communication technique is considered that uses shorter pulses at the same recurrence rate to eliminate the sky wave and avoid its degradation. Three analyses show the wideband technique is substantially better than a conventional narrow-band system with respect to transmitter power required for a specified error rate, its susceptibility to atmospheric noise interference, and its sensitivity to unwanted signal interference. Author