Practical Implementation of Digital Down Conversion for Wideband Direction Finder on FPGA

 

Vuk Obradović

Predrag Okiljević

Nadica Kozić

Dejan Ivković

 

Modern direction finders are designed as sensors for interception of radio signals in wider instantaneous bandwidth. Software radio technology offers ability to develop wideband direction finder architectures with programmable intermediate frequency, instantaneous bandwidth and frequency resolution. In this paper implementation of synchronous digital down conversions (DDCs) for wideband direction finder on FPGA is presented. DDCs are used to downconvert signal from intermediate frequency (IF) to baseband. For wider bandwidth DDCs need to be implemented on FPGA which combines the flexibility of a general-purpose DSP plus the speed, density, and low cost of an application-specific integrated circuit (ASIC) implementation. Measurements and computation of input signals from five channels in parallel on two FPGA devices is presented. Benefits of high speed parallel computing have been observed and discussed in this work. System performance and measured results are briefly presented in paper.

Key words: direction finder, wide bandwidth, programmable device, signal conversion.