Software Defined Radio
Software Defined Radio
Part 1
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 ,
according to security reasons i am not showing transmission of open source signals but soon i will update how to pentest the replay attacks of key fobs and smart door lock systems.
what we going to discuss
1. Introduction about Radio And Software
Defined Radio
2. Various types of devices
3. Antennas
4. Radio waves
5. Capturing the FM Signals And
Analyzing
Requirements:
1. Software Defined Radio (SDR)
2. Antenna
3. GQRX software for Linux
, windows - SDR software
4. Gnu Radio Companion
5. Computer
Radio:
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.(Wikipedia)
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.(Wikipedia)
Some other
different SDR Devices for testing radio signals
1. AirSpy
2. Hackrf
3.Bladerf
4.Sdrplay
5.USRP2
Antennas
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. (wikipedia)
Types
of antennas..
1. Wire
Antennas
2.
Travelling Wave Antennas
3. Reflector
Antennas
4.
Microstrip Antennas
5.
Log-Periodic Antennas
6. Aperture
Antennas
Radio
Waves
Radio waves are
a type of electromagnetic radiation with wavelengths in the electromagnetic
spectrum longer than infrared light. Radio waves have frequencies as high as
300 GHz to as low as 3 kHz, though some definitions describe waves above 1 or 3
GHz as microwaves, or include waves of any lower frequency. At 300 GHz, the
corresponding wavelength is 1 mm (0.039 in), and at 3 kHz is 100 km (62 mi).
Like all other electromagnetic waves, they travel at the speed of light.
Naturally occurring radio waves are generated by lightning, or by astronomical
objects.(Wikipedia)
Analyzing
FM Signals:
Connect SDR To Computer as shown below
And Connect Discone Antenna , here we are using
Discone antenna
To get more signal radius of long distances. specially people will use parabolic antennas to get long distance radio signals practically proved already
After connecting SDR , Run the gqrx and set the
appropriate frequency for the testing the FM Signal Example: 93.5mhz
Features of gqrx
.. Process
I/Q data from the supported devices.
.. Change
frequency, gain and apply various corrections (frequency, I/Q balance).
.. AM, SSB,
CW, FM-N and FM-W (mono and stereo) demodulators.
.. Special
FM mode for NOAA APT.
.. Variable
band pass filter.
.. AGC,
squelch and noise blankers.
.. FFT plot
and waterfall.
.. Record
and playback audio to / from WAV file.
.. Record
and playback raw baseband data.
.. Spectrum
analyzer mode where all signal processing is disabled.
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
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 as shown below and
click on run
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
What we did in this part its just a ordinary FM
Stationary Signals analyzing so this is not much interesting for next signal
analyzing module a bit interesting to coma
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