Microprocessor-Controlled Radio Synthesizer - 1

EE MICROPROCESSOR-CONTROLLED RADIO SYNTHESIZER 1 The addition of a microprocessor-controlled synthesizer to a continuously-tuned receiver greatly improves tuning accuracy and provides several additional facilities that have become available in recent years. The versatile synthesizer described has a 6-digit LCD or LED display and a 16-position keyboard which allows direct frequency entry, channel or frequency increment or decrement, as well as the storing and recalling of 30 frequencies. The MW, SW and FM band are covered each with a choice of IF offsets. Most recently designed quality radios employ synthesized local oscillators con- trolled by a microprocessor. These com- plex designs should not discourage the advanced home constructor, however, as components are currently available which enable similar facilities to be either incorporated in individual designs, or added to existing radios. Synthesis of the local oscillator (LO) in a superheterodyne receiver provides many advantag...