Undersampled Digitally Heterodyned SFGPR with Variable Sampling Frequency

In this paper, an innovative architecture of an udersampled digitally heterodyned stepped frequency GPR is presented. Tipically SFGPR perform a quadrature downconversion in the analog domain to detect targets; the main disadvantages of this approach can be eliminated by performing it in the digital domain. In order to perform such digitally downconversion, the echoes of the step frequencies transmitted are subsampled with a sampling frequency variable on a step by step basis according to rules described hereafter. This approach allows to greatly simplify both the transmitting and receiving chains of the SFGPR by eliminating a frequency conversion stage. The key aspects of architecture presented and its advantages are discussed. It is well known that the capability of electromagnetic waves to propagate beyond the physical dis- continuities of propagation media makes it possible to exploit them to investigate internal features of dielectric bodies. From this property, an endless number of practical applications have been arisen, ranging from medical prospecting to detection of mines, nondestructive testing of industrial items and GPR applications. In this paper, a new architecture of an Undersampled Digitally Heterodyned SFGPR with variable sampling frequency is presented. This design starts by the technical knowledge and on fleld experience achieved during the design of a SFGPR developed in the framework of the ARCHEO project; it was funded by the Italian Ministry of the scientiflc research and industry whose main aim was the development of tools to aid the archeologists in their on fleld researches (1). The key aspects and the advantages of the architecture herein presented are discussed.