Mixed analog/digital transmission system using radio link and method of operating same

摘要

A receiving station for analog and digital messages, transmitted via a radio link, includes a sensor for a pilot frequency fp and a detector for a noise frequency fn both lying within the frequency spectrum of digital signals. A simulator at the receiver generates the noise frequency fn during high-speed digital transmission in response to an incoming frequency f1 lying outside that spectrum; this simulator may also include a local source of pilot frequency fp or an equivalent signal generator which actuates the corresponding sensor in the presence of a synchronizing signal accompanying the digital message.