Software defined radio

SOFTWARE DEFINED RADIO

Sandesh K A

4NI11EC047

OUTLINE

Introduction

Circuit design

Working

Applications

Benefits

Disadvantages

Future Scope

Introduction

What is SDR ?

It is a technology wherein software modules running on a generic hardware platform consisting of DSPs and general purpose microprocessors are used to implement radio functions

WHY SDR ?

To produce a radio that can receive and transmit a new form of radio protocol just by running new software.

A technique in which all the processing is done in software i.e., mixing, filtering, demodulation etc.

Used to implement different demodulation scheme and different standards can be implemented in the same device.

Can be updated so that device doesn’t become obsolete with time.

If software does everything what

is the role of hardware ?

Hardware is still needed for the RF front end and Analog to Digital Convertor (ADC) and Digital to Analog converter (DAC).

Basic radio receiver unit

SDR ARCHITECTURE

HARDWARE

Low Cost

RTL2832U-Realtek SDR 24-1766 MHZ $10-$30

dongle

Medium cost FunCube DonglePro 150kHz-2.05GHz $124.99-200

HackRF One 10MHz-0.6GHz £299

BladeRF 300MHz-3.8GHz $420-$460

High cost :

USRP! $707

USRPB200 70MHz-6GHz $675

UmTRX 300MHZ-3.8GHz $1500

SOFTWARE

Windows , Mac and Linux (Cross Platform)

GNU Radio Toolkit used by most SDR Open Source

(includes GNU Radio

Companion)

Linard Library used to interface Open Source

with hardware

Windows

SDR# spectrum viewer Open Source

HDSDR spectrum viewer Open Source

Mac and Linux

Gqrx spectrum viewer Open Source

Android

SDR touch Free(trail)/$9.99 pro

RTL2832U driver Driver for RTL-SDR

ADSB Receiver Free

ADS-8 on USB SDR RTl $1.50

Software communications architecture

(SCA)

Provides a real-time software operating-system environment to support the dynamic waveform generation and signal processing aspects of a radio , as well as the administrative aspects for radio installation and change control.

Such an example of standardized architecture of hardware and software will lead to generic, flexible radio systems which may be loaded with applications to suit particular operating scenarios.

SDR may be flexible enough to operate in several modes at the same time and some may be capable of changing or adding modes while continuing operation in other modes.

SCA INTERFACE WITH SDR

CORBA(common object request broker architecture)

CORBA is the Object Management Group’s open architecture that provides the infrastructure for computer applications to work together over a network.

It has been chosen as the middleware layer of the Software Communications Architecture (SCA), because of the wide commercial availability of CORBA products and its industry acceptance.

Used to provide a cross-platform middleware service that simplifies standardized client/server operations by hiding the actual communication mechanisms under an object request broker software bus

GNU radio software:

FM demodulation example in GNU Radio

Python auto generated code

from gnuradio import analog

from gnuradio import audio

from gnuradio import blocks

from gnuradio import eng_notation

from gnuradio import gr

from gnuradio import window

from gnuradio.eng_option import eng_option

from gnuradio.gr import firdes

from gnuradio.wxgui import fftsink2

from gnuradio.wxgui import forms

from gnuradio.wxgui import scopesink2

from grc_gnuradio import wxgui as grc_wxgui

from optparse import OptionParser

import wx

class dial_tone(grc_wxgui.top_block_gui):

def __init__(self):

grc_wxgui.top_block_gui.__init__(self, title="Dial Tone")

_icon_path = "/usr/share/icons/hicolor/32x32/apps/gnuradio-grc.png"

self.SetIcon(wx.Icon(_icon_path, wx.BITMAP_TYPE_ANY))

self.samp_rate = samp_rate = 32000

self.noise_slider = noise_slider = .005

_noise_slider_sizer = wx.BoxSizer(wx.VERTICAL)

Applications Of SDR Technology

Public safety

Cell phone technology

Military applications

Commercial use of SDR

Benefits Of SDR Technology

User benefits (personalized modulation scheme)

Manufacturer benefits

Interoperability

Intelligent transport systems (ITS)

Space considerations

Power considerations

Reconfiguration considerations

Other land mobile systems

Disadvantages of SDR:

There are technology limits on achievable RF performances

For very wide frequency coverage, the RF hardware may need to be built in separate portions of circuitry dedicated to particular frequency ranges

Two tone Inter Modulation Distortion(IMD)

The choice of architecture depends on the available technology

Complexity in using the software

Software reliability may define overall radio reliability, rather than hardware limitations

Future Scope Adaptive Radio : Communication Systems which have means of measuring their own

performance and alter them to provide high performance. SDR helps to provide high degree of freedom

Cognitive Radio: Communication systems are aware of

their internal state and environment,

such as location and utilization on RF

frequency spectrum at that location.

They can make decisions about their radio

operating behavior by mapping that

information against predefined objectives.