DSP-based On-line Microwave Cigarette Density Monitoring System

To avoid the damage to environment and human body in cigarette density monitoring with a radioactive source,a system using a metal resonant cavity as density sensor was designed,which was composed of a microwave signal generating and receiving module,a microwave resonant cavity and a data processing module.A metal microwave resonant cavity with a through hole was used,resonant frequency excursion and power attenuation would fluctuate in line with the density variation of the tobacco rod traveling through the resonant cavity.The high-speed DSP in the data processing module calculated rod density accordingly.The results of on-the-spot test showed that there was no significant difference between microwave system and radioactive system in terms of average weight control;with a standard deviation of less than 25 mg,microwave system was slightly better than radioactive system in standard deviation control.