ABSTRACT
Along with the electronic technology and the subminiature primary device development, the portable product which high grade, the low energy consumption, the multi-purpose small sounds, the video frequency product and the computer unify are more and more many, small, facile, artistic, the multi-purpose radios have become the most popular radio now.
In order to realize the radio multi-purpose, has used the monolithic integrated circuit control system and the phase-locked loop frequency synthesis harmonious way.May realize automatic and the manual frequency modulation, also can realize broadcasting station memory and carrier frequency functions and so on demonstration.
The radio overall system realizes the entire electric circuit 3V power supply by the DC-DC direct-current converter；use the FM/AM receiver integrated chip of SONY company to design and finish mixing, mid—wave amplifying and demodulation of Receiver；use PLL frequency synthesizer tuner chip to produce stable self-vibration and the frequency of controlling input tuning loops,and thus to realize electric tuning; use MCS-51 Serise of SCM to control the frequency synthesizer，and with keyboard，displaying and memory medium we can auto-search the radios,save the radios,display the carrier frequency.
Keywords:Frequency modulation; SCM;PLL frequency synthesizer;
Frequency shows
