This document discusses using a Pluto-SDR device with GNU Radio Companion software to implement basic digital signal processing and modulation schemes. It describes how software defined radio works by implementing hardware processes in software. Simple modulation schemes like AM and FM were tested using the Pluto-SDR with GNU Radio and an oscilloscope tool to view the output signals. Cyclic sine waves, AM modulation, and an FM receiver were implemented as examples. The goal was to learn the concepts of software defined radio in a practical way using open source tools.

1. Signal Processing using
Pluto-SDR
Bhavna Singh, 15116012 Lab Based Project
Rohit Raushan, 14116058 B.Tech. 3rd yr, ECE
Under the supervision of : Dr. Meenakshi Rawat

2. Abstract
● Here we represent the basic idea about the Software Defined Radio (SDR) and
have demonstrated the fundamental digital modulation schemes.
● SDR is a technique which can be used to replace the current hardware.
● Implementation of simple modulation schemes like AM,FM and tested
different modulation circuits to test our Pluto-SDR connectivity with GNU
Radio signals and IIO-Oscilloscope..
Software Used: GNU Radio Companion,
IIO-Oscilloscope.

3. Presentation Flow:
1) Software Defined Radio
2) Hardware Platform( Pluto-SDR)
3) GNU Radio Companion
4) IIO-Oscilloscope
5) SDR Working Model
A) Transmit Test
B) FFT & Waterfall Sink Test
C) IIO Oscilloscope
6) GRC Implementation
A) Cyclic Sine Wave
B) Amplitude Modulation
C) FM Receiver
7) Conclusion & Reference

4. Software Defined Radio
● A complete software implementation of hardware processes.
● Hardware like filters, amplifiers, modulators etc are implemented in
embedding devices.
● Hardware complexity is widely reduced.

5. Software Defined Radio
● Dynamic nature of modifying the system parameters without changing the
hardware part.
● Effective solution to the very high cost and limited flexibility of hardware based
radios.
● Hardware Platforms: Adalm Pluto-SDR, RTL-SDR, FPGA Board.

6. ADALM-PLUTO SDR
Active device features independent receive and transmit channels that can
be operated in full duplex.
FEATURES:
➢ Portable self-contained RF learning module
➢ Cost-effective experimentation platform
➢ RF coverage from 325 MHz to 3.8 GHz

7. FEATURES:
➢ Flexible rate, 12-bit ADC and DAC
➢ Small sized enough to put in a pocket
➢ GNU Radio sink and source blocks
➢ Up to 20 MHz of instantaneous bandwidth (complex I/Q)
➢ Two antennas (824 MHz to ~894 MHz/ 1710 MHz to ~2170 MHz)

8. Pluto-SDR-Hardware (AD9363)

9. GNU Radio Companion
● GNU Radio is a free & open-source software development toolkit.
● Provides signal processing blocks to implement software radios.
● It can be used with readily-available low-cost external RF hardware
to create software-defined radios, or without hardware in a
simulation-like environment.
● It’s a graphical tool for creating signal flow graphs and generating
flow-graph source code.

10. II0 Oscilloscope
● IIO Oscilloscope is a product from Analog Devices, Inc. that uses libiio to
interface with Linux IIO devices.
● It is a great tool not only for demonstrating capabilities of Analog Devices'
products but also for testing, debugging and fine-tuning an RF system.

11. SDR Working Model
● In SDR, signal is captured by an antenna which is further converted into
digital samples with regular intervals.
● These digital values are then processed in software.
● The resulting output can be then converted back into audio, video or required
form.

12. Testing on PlutoSDR
1) Transmit test
Next we tried adapting a simple transmit test by creating a
flowgraph sending and receiving signal via Pluto-SDR.
Transmit Performance:
★ Output Power (how far can I transmit)
★ Output Fidelity (how accurate is the transmission)

13. Transmit Test

14. 2) FFT & Waterfall sink
● We tested a simple FFT and Waterfall sink using the Pluto SDR source.
● We set the sample rate to the maximum of 61.44 MSPS, and the RF
bandwidth to 60M. we were able to see the 900 MHz GSM band.
● It seemed the max sample rate is not used as the output is only 30 MHz, or
perhaps it’s only one ADC.

15. FFT & Waterfall Sink

16. IIO-OSCILLOSCOPE
We tested using the PlutoSDR IIO-OSCILLOSCOPE software and were able to
generate a FFT spectrum of the GSM band

17. Cyclic Sine Wave
Block Diagram Constellation Plot

18. Cyclic Sine Wave Output Plots:
FFT PLOT Waterfall Plot

19. Amplitude modulation
The modulation of a wave by varying its amplitude, used especially as a means of
broadcasting an audio signal by combining it with a radio carrier wave.

20. Amplitude Modulation Plots:

21. FM Receiver Plot with GRC Block Diagram

22. CONCLUSION
● We have implemented simple modulation schemes and tested different
modulation circuits to test our Pluto-SDR connectivity with GNU Radio signals
and IIO-Oscilloscope.
● This concept of SDR using GNU Radio helps us to learn the concepts
practically.
● Our work is to get familiar with GRC open source software tool. The basic
demonstrations are done using the basic theories of communication
systems.
● One single Universal Software Radio Peripheral (USRP) can implement all the
modulations and multiplexing techniques in real time.

23. REFERENCE
1. https://www.mouser.in/new/Analog-Devices/adi-adalm-pluto/
2. http://www.csun.edu/~skatz/katzpage/sdr_project/sdr/grc_tutorial.pdf
3. https://www.sciencedirect.com/science/article/pii/S187770581200985X
4. http://oz9aec.net/radios/gnu-radio/grc-examples
5. Analog and Digital Modulation Toolkit for Software Defined Radio-paper
published by R.Gandhiraja , Ranjini Ramb , K.P.Somanb
6. Bard, John and Kovarik, Vincent, “Software Defined Radio: The Software
Communications Architecture,” Wiley Series in Software Radio, 2007

24. Thank You