International Journal of Science, Engineering and TechnologyAuthors: Capt Arun Pundir
Abstract: The electromagnetic spectrum has become a decisive dimension of modern tactical operations, yet the receivers traditionally fielded for spectrum surveillance still scan one narrow channel at a time and can miss short, intermittent, or frequency-hopping transmissions. This paper presents TARANG, a man-portable passive radio-frequency (RF) monitoring system built around low-cost software-defined radio (SDR) hardware and open tooling. TARANG uses a HackRF-class SDR driven by a wideband sweep engine to observe an entire frequency band near-simultaneously, and a purpose-built digital signal-processing (DSP) chain to turn each sweep into a clean list of detected emitters with an accurate carrier frequency, received power, and signal-to-noise ratio. A parabolic peak-refinement step recovers the carrier location between fast-Fourier-transform (FFT) bins, while multi-sweep averaging, an adaptive noise-floor gate, adjacent-bin grouping, and channel bucketing together suppress spurious detections and stabilise the reported frequency of a fixed transmitter to a single channel. A baseline-driven module flags jamming and interference against a learned per-band reference, and an optional KrakenSDR five-channel coherent array provides relative bearing (direction finding) to a chosen target frequency. The complete system runs on a small tablet-class computer, is powered from a field battery, and logs every detection for later analysis. Field testing against a handheld land-mobile radio confirmed that the refined pipeline resolves a transmitter to its exact operating channel with stable, repeatable readings, in contrast to the several-hundred-kilohertz wander produced by a naive peak reading. TARANG demonstrates that a capable, deployable spectrum-monitoring and direction-finding capability can be assembled at a small fraction of the cost of conventional surveillance receivers.
