基于DDS和PLL技术的便携式数字扫频仪的设计

设计了一款体积小、功耗低、使用灵活、成本低廉的便携式数字扫频仪。系统的硬件设计采用DDS(直接数字式频率合成器)技术产生0~70 MHz的输出频率,电容三点式压控振荡电路及MB1507琐相环电路产生70~500 MHz的输出频率,并用自动电平控制电路,保持输出振幅的稳定,用程控衰减电路实现输出幅度的连续可调。软件设计实现了扫频步进长度的连续可调、及对波形峰值和谷值点的标识。设计创新地使用DDS和PLL技术产生扫频信号,用PIN二极管取代继电器作为波段开关,增加频率的测量范围,提高了系统的响应速度和可靠性。测试结果表明:基于该方案设计的便携式数字扫频仪性能稳定,各项指标优良,频率测量范围为0~500 MHz。

Design of portable digital frequency sweeper based on DDS and pLL technology

The portable digital frequency sweeper was designed, which had the advantages of small volume,low power consumption, using flexibly and low-cost. The hardware of this system using DDS （ Direct Digital Frequency Synthesizer） technology could produce 0 -70 MHz, the oscillator circuit of three-point capacitance and MBI507 PLL（ Phase-Locked Loop） could generate 70 - 500 MHz, and ALC plitude stability, with the programmable attenuation circuit realizing （Automatic Level Control）kept the output am- the continuous adjustable output amplitude. De- sign of the software implemented a continuous frequency scanning of step length and identifications of waveform peak and valley. The innovation which DDS and PLL produced scanning signal and replaced relay as the band switch with the PIN diode increased the range of measuring frequency and improved the response speed and reliabil- ity of the system. The test results showed that the portable digital frequency sweeper based on this scheme had some advantages, such as stable performance, better results and wide frequency from 0 Hz to 500 MHz.