Radio Communications Receivers--Future Trends

Today, the classical receiving system is changing rapidly, due to advances in many technologies. The communications receiver of tomorrow will be increasingly called upon to assume demanding tasks of signal processing in a complex environment. Extremely high speed frequency scanning and processing of the received data must take place in order to insure the highest probability of intercept. Extensive use of microprocessors will allow for immediate digestion and interpretation of the received data.

Digital filters* are also being implemented in conventional i-f amplifiers, and as their sampling frequency is increased, they are considered as total signal processors in a no-conversion, TRF-type receiver.

New developments in analog and digital filters should allow for the realization of single up-conversion receivers which can achieve the required final selectivity in the first i-f. Extremely high dynamic ranges will be required to cope with the future's densely-populated rf environment. It is possible that the receiver of the future will be a hybridized approach involving several generic receiver types such as the superheterodyne, tuned radio frequency (TRF), and/or Bragg-cell, providing an increased probability of intercept over the conventional types.

In retrospect, it is hard to believe that only eighty years ago, the first intelligent signal was heard with a coherer-type receiver. This guide had attempted to cover technical achievements in radio receiver design over this relatively short period of time. It is hoped that the guide will serve as stimulus for creativity in those interested in technical excellence.

['Digital Filters use discrete time samples of the input signal to output similar samples as modified by arithmetic, computer-like operations. The result is that an analog filter is implemented dignity. allowing for dunes in parameters to be easily obtained by modifying the software.]