Designing a Narrowband Radar using GNU Radio and Software Defined Radio for Tomography and Indoor Sensing

Abstract

This project achieved both high accuracy and low cost in a narrowband radar design by combining the unpopular Multiple Frequency Continuous Wave (MFCW) radar algorithm with the low-cost Software Defined Radio (SDR) on the GNU Radio platform. According to traditional Pulse or FMCW radar technologies, a typical SDR with 4MHz BW will have a theoretical accuracy limit of 3750cm (i.e. inaccuracy equivalent to the size of a large house). However, this project established the first SDR-based MFCW radar in the 2.4-2.5GHz band using two Continuous Waves (CW) with only a few kHz BW and a superior range accuracy of 15cm. Despite a lack of applicable publications on MFCW radar, a distance sensing algorithm capable of automatically correcting erroneous results from direct delta phase calculation was able to be created. This proof of concept opens the doors to many short-range radar applications using the emerging low power and low cost SDR technology. However, this project also revealed a non-linear phase issue that will need future improvement.