SDR is Software defined Radio is used for the to Capturing and analyzing the various radio frequency signals , we can monitor and transmit the signals also .
what we going to do
- Introduction about Radio And Software Defined Radio
- Radio waves
- Capturing the FM Signals And Analyzing
- Software Defined Radio (SDR)
- GQRX software for Linux , For windows – SDR Sharp
- Gnu Radio Companion
Radio is the technology of using radio waves to carry information, such as sound, by systematically modulating some property of electromagnetic energy waves transmitted through space, such as their amplitude, frequency, phase, or pulse width.
Software Defined Radio (SDR):
Radio communication system where components that have been typically implemented in hardware (e.g. mixers, filters, amplifiers, modulators/demodulators, detectors, etc.)are instead implemented by means of software on a personal computer or embedded system.
Mainly we using for capturing air traffic
An antenna , or aerial, is an electrical device which converts electric power into radio waves, and vice versa.It is usually used with a radio transmitter or radio receiver.
Types of antennas..
- Wire Antennas
- Travelling Wave Antennas
- Reflector Antennas
- Microstrip Antennas
- Log-Periodic Antennas
- Aperture Antennas
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light.
Analyzing FM Signals:
Connect SDR To Computer as shown below
And Connect Discone Antenna to SDR , and here we are using the Discone antenna to get more signal strength from air
After connecting SDR , Run the gqrx in computer and check frequency for the FM Signal Example: 93.5mhz
Here we can observe in that particular frequency range there thick line visible , it means the radio wave consists the audio
Gnuradio is written in Python and it is using for Signal processing and without hardware in a simulation-like environment. It is widely used in hobbyist, academic, and commercial environments to support both wireless communications research and real-world radio systems.
Download from here https://goo.gl/ccBhqI
To Install Gnuradio in Ubuntu follow the command
#sudo apt install gnuradio-companion
To Analyze the FM Signal with Gnuradio , download and open with gnuradio-companion
And set the frequency in Wx gui block as shown below and click on run ,here i am using default value 93.5e6
The Fast Fourier Transform (FFT) is simply a fast (computationally efficient) way to calculate the Discrete Fourier Transform (DFT).
Fourier analysis converts a signal from its original domain (often time or space) to a representation in the frequency domain and vice versa.
Here we can see in FFT Plot (Fast Fourier transform) shown below
A waterfall plot is a three-dimensional plot in which multiple curves of data, typically spectra,are displayed simultaneously.And here it is waterfall plot Image
We did test with Ordinary FM Signals so there no encryption and decryption but next part2 consists interesting topics like Decrypting the signals.