Design Of High Precision Signal Generator

The frequency source is the radar, the correspondence, the electronic countermeasure and the electronic system realization high performance target key, the very many modern electronic installation and the system function all directly relies on in uses the frequency source the performance, therefore the frequency source is explained by the people for the multitudinous electronic system;the heart;. But the high performance frequency source realizes now through the frequency synthesis technology. The frequency synthesizer uses or many standard signals, produces the massive discrete frequencies signal equipment through each technical way. The traditional frequency synthesizer has the direct simulation synthesis and the phase-locked loop synthesis two kinds. The direct simulation synthesis use frequency multiplication, the frequency division, the mixing and the filter, have the frequency from sole or several reference frequencies which many institutes need. This method frequency switching time quick (is smaller than 100ns), but the volume big, the power loss is big, at present basic has not been used. The phase-lock concentric type frequency synthesizer has the very good narrow band track characteristic, may choose well needs the frequency the signal, the suppression stray component, and has avoided the massive filter, is advantageous in the integration and the miniaturization.The direct digital frequency synthesizes (DDS) is one kind of new frequency synthesis technology which the recent years developed. Its main merit is the relative band width is very wide, the frequency switching time is extremely short (may small than 100ns), the frequency resolution is very high, the entire digitized structure is advantageous for the integration, the output phase continuously, the frequency, the phase and the scope may realize the program control. Therefore, can unify closely in with the computer together, fully displays the software the function. As the application, had the DDS product to use in the receiver local oscillation, the signal generating device, the communications system, the radar system, the frequency-hopping communications system now and so on.This system uses the STC89C52RC monolithic integrated circuit is a core, auxiliary by necessity simulation, digital circuit, constituted one based on the DDS technology sine wave signal generating device. This software system uses the 4*4 keyboard operation, carries on the demonstration by the menu form, the ease of operation is simple, the software increased many functions. It through starts DDS, after delivers the memory buffer area data read-out DDS to output the corresponding frequency, and the data conversion is the BCD code, carries on the demonstration through the liquid-crystal display. This system volume small, the stability, the precision are extremely high, facilitate the carryhome, is suitable in contemporary [onlinetranslation] and so on acme communications system and precise precision instrument as well as high frequency wireless transmission systemThe author has developed an actual signal generator using the DDS technology, and has given based on the DDS technology signal generating device electric circuit diagram, the design process and the detailed software procedure. Through the prototypical test result, proved the Ming dynasty printed books signal generating device to achieve the anticipated design request, its performance index surpassed traditional obviously the function generator.