Wide-band channel for emergency communication

A single wideband channel could be assigned to all short range emergency communication systems, resulting in better service and better spectrum utilization. Many independent VHF or UHF mobile users or military nets could use this one channel at random without any form of centralized control or synchronization, and each could transmit different simultaneous emergency messages without significant mutual interference. In reviewing wideband modulation and addressing (coding) techniques, it is shown that Delta modulation and discrete frequency coding is best suitable for this application.