Abstract
Satellite and low-power wireless communication systems require flexible and low-cost tools for real-time radiofrequency monitoring, signal identification, and preliminary performance assessment. Conventional spectrum analyzers
and dedicated satellite receivers can be expensive and relatively inflexible for field applications. This paper presents the
design and performance evaluation of a portable software-defined satellite signal analyzer based on a Yagi antenna, lownoise amplifier (LNA), RTL-SDR receiver, ESP32 microcontroller, and HDSDR software. The system was developed to
provide real-time visualization and analysis of RF signals, with experimental monitoring focused on the 433.92 MHz LoRa
band as a representative UHF signal source. The Yagi antenna provides directional reception, while the LNA improves the
received signal level before digitization by the RTL-SDR. HDSDR performs spectrum visualization, waterfall display,
tuning, bandwidth selection, and signal-level monitoring, while the ESP32 provides auxiliary system monitoring and
portable interface functions. Experimental results indicate that the addition of the LNA improved the received signal-tonoise ratio from approximately 6.1 dB to 14.8 dB and increased the detectable signal level by approximately 8.7 dB. The
system successfully identified the 433.92 MHz LoRa carrier and provided continuous spectrum and waterfall visualization.
The proposed analyzer demonstrates the feasibility of combining inexpensive SDR hardware and embedded control into a
compact field-deployable RF monitoring platform. The architecture can be adapted to satellite telemetry and S-band
applications by replacing the antenna and RF front-end components with frequency-appropriate devices.