AN1631-Simple Link Budget Estimation and Performance
AN1631 Simple Link Budget Estimation and Performance Measurements of Microchip Sub-GHz Radio Modules Usually, Sub-GHz channels are part of unlicensed Author: Pradeep Shamanna Industrial Scientific Medical (ISM) frequency bands. Microchip Technology Inc. Sub-GHz nodes generally target low-cost systems, with each node costing approximately 30% to 40% less compared to the advanced wireless systems and uses INTRODUCTION less stack memory. Many protocols such as IEEE ® The increased popularity of short range wireless in 802.15.4 based ZigBee (currently, the only protocol home, building and industrial applications with Sub- offering both 2.4 GHz and Sub-GHz versions in the GHz (<1 GHz) band requires the system designers to 868 MHz and 900 MHz bands), automation protocols, understand the methods, estimation, cost and trade-off cordless phones, Wireless Modbus, Remote Keyless in short range wireless communication. Apart from Entry (RKE), Tire Pressure Monitoring System (TPMS) considering the range estimation formula, it is good to and lot of proprietary protocols (including MiWi™), understand the wireless channel and propagation occupy this band. However, operation in the Sub-GHz environment involved with Sub-GHz. Generally, RF/ ISM band induces the radios to interfere with other wireless engineers perform a link budget while starting protocols utilizing the same spectrum which includes an RF design. The link budget considers range, threat from mobile phones, licensed cordless phones, transmit power, receiver sensitivity, antenna gains, and so on. frequency, reliability, propagation medium (which This application note describes a simple link budget includes the principles of physics linked to reflection, analysis, measurement and techniques to evaluate the diffraction and scattering of electromagnetic waves), range and performance of wireless transmission with and environment factors to accurately calculate the results, and uses developed models to estimate the performance of a Sub-GHz RF radio link.
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