X-band FMCW Radar for Infestation Monitoring of Grain Silos

Abstract

The world population is increasing exponentially causing several problems, one being the food deficiency, that is also victimizing Pakistan. To control this food deficiency, the increase in crop production is one solution. Only in Pakistan, production of wheat, maize, and rice have increased by 13.63 %, 41.40 %, and 11.18%, respectively from the year 2011 to 2017. However, despite this increase, the wastage of food, which is around 1.3 billion tones globally still remains a major factor of food deprivation. To prevent food wastage, minimizing post harvesting losses by adopting grain storage can be an excellent option. However, improper and inefficient storage of grains can cause insect infestation thus contributing post-harvesting losses instead of preventing it. To cater this issue, Silos are considered the best storage mechanism of grain but is still prone to insect attacks. Manual monitoring techniques, based on temperature and humidity monitoring, for insect infestation in Silos are available, however, each has its own limitations. This research work aims to use radar technology to detect infestation of grain stored within Silos. Based on the FMCW concept, the radar approach has been utilized for level measurement in the literature, however, this work extends its application further leveraging on the high resolution and sensitivity and zero target radial motion threshold. At first, the RCS of the Lepidoptera family, which includes grain’s insect moth, is calculated for different orientation and polarization angles, which ranges from 0.007 to 6.40. The radar is designed by its governing equation using MATLAB, while system level simulations are performed in Genesys and ADS by considering a two antenna architecture. The receiver sensitivity of this radar comes out to be -111.5 dBm while output power after the IF stage is - 63.5 dBm. The components of each module are chosen among others, based on their superior performance in a given frequency range, their cost, and their ease of delivery in Pakistan. The RF PCBs of these individual components are designed and co-simulated using ADS. Radar is developed using a packaged based modular approach and COTS based single board approach. Each radar module was developed and tested before integrating into a whole system. The testing of each module was according to the design requirement for both modular-based and COTS-based radar system. The integrated systems were successfully tested using spectrogram and Labview for frequency vs range. These radar systems were then placed at the top of the silo, which successfully detected movement of an insect, having a size of 3 cm, inside an empty silo, as well as in the presence of wheat husks, straws, and pure wheat. MTI algorithm is used for signal processing, which not only detected the movement of insect but also detected insect’s motion beneath the wheat husk, straws, and pure wheat