Submitted to: Journal of Cotton Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/1/2005
Publication Date: 6/1/2005
Citation: Pelletier, M.G. 2005. Multi-path interference mitigation for cotton bale microwave moisture sensing. Journal of Cotton Science. 9(3):135-144. Interpretive Summary: In the production and processing of cotton lint in cotton gins, the control over moisture plays a key role in maintaining quality and productivity levels. The latest developments in this industry have seen a rise in the use of cotton moisture restoration systems. To date, only a few very expensive units are available which can be used to determine an accurate moisture content. This research is part of an ongoing research effort to develop a low cost non-contact accurate moisture sensor. The sensor under investigation is a microwave-based system that is based upon measuring the electrical permitivity of the cotton bale. This measurement has provided accurate results in a lab environment, but has yielded varying calibrations when placed into operation in commercial cotton gins. Previous research has indicated that when this technique is performed in metal clad structures, the measurement is affected by multi-path interference. This portion of the research was undertaken to explore alternative modulation methods to reduce or remove this multi-path interference from the measurement. This paper develops a technique by which the multi-path interference can be significantly reduced. In order to explore this technique, a model was developed by which to simulate the effect of multi-path interference on the measurement, as well as to quantify the performance of the new multi-path reduction technique. The results of the simulations show a significant improvement over the previous methodologies and provide insight into the best utilization of this technology.
Technical Abstract: Previous research indicated that the effects of multi-path interference upon a microwave cotton moisture sensor are significant enough to force a completely new calibration for each and every installation. This is an expensive and time-consuming task. Therefore, this research was undertaken to determine if a system could be deigned that would be impervious to multi-path interference.