Diseño e implementación de un prototipo de analizador de espectro radioeléctrico utilizando software libre sobre Raspberry Pi para radio Rio FM.

Abstract

In the present work it was designed and implemented a prototype of an analyzer spectrum with free software on Raspberry Pi in the Rio FM radio in the city of Riobamba, fulfilling the specific requirements for displaying radio-electrical signals in the frequency domain and determine the parameters that are present in the radio-electric spectrum, such as: frequency, power, interference and intermodulation. It was found and design the functionality of each part of the device and could perform FM demodulation; identify the relationship signal to noise, calculation of the bandwidth and maximum power. The hardware components is taken into account, to tune the frequencies with the chipset R820T and demodulating the signal with the chipset RTL2832U that use COFDM (Coded Orthogonal Frequency Division Multiplexing), which, allow to receive signals broadcasting band FM between 88 and 108 MHz and the software elements rtl-sdr, rtlizer, pyrtlsdr, freqshow and GNU Radio, to form a Software Defined Radio (SDR), all of them distributed and installed in the operating systems Raspbian and Ubuntu Trusty, allowing implement a device with components of low consumption of power, touch screen, USB ports for communication of peripherals and computer connection, MCX antenna connectors, SPAN of 240-300 kHz and of 910-3200 kHz, and activation of Max Hold, for maximum peak and average for the signal. Further comparison with other analyzers brands such as Rohde & Schwarz and Anritsu, obtaining variations around 10 kHz with the prototype developed. It was concluded that the use of this prototype allows to realize measurements of bandwidth with an application developed for the measurement of this parameter and see the changes that may exist in the pattern of the spectrum of the radio-electric signal, for the detection of possible interferences, which was recommended use it in other stations FM broadcasting and in the band of 24 MHz to 1.85GHz for which it operates the prototype developed.