Introduction toIntroduction toSoftware Defined RadiosSoftware Defined Radios

Steven Bible, N7HPRTucson Amateur Packet Radio, Inc.

AgendaAgenda

! Why Software Defined Radios?

! What is a Software Defined Radio?

! Block Diagrams

! Technical Challenges

! Amateur Contributions

! How to Build A SDR– The DSP-10 As a SDR

! Supporting Documentation

! Conclusion

Why Software Defined Radios?Why Software Defined Radios?

! Comments of ARRL:

“ARRL is most interested in this proceeding, not onlybecause of the utility of the Amateur Radio Service as atesting ground for different configurations of SDRs, butalso because of the potential long-term opportunities forSDRs to effect substantial changes, even conceptualchanges, in traditional frequency assignment and spectrumallocations decision making in all services.”

ARRL comments to the Notice of Inquiry Regarding Software Defined Radiosdated June 14, 2000 (ET Docket No. 00-47 released March 21, 2000).

http://www.fcc.gov/searchtools.html

Why Software Defined Radios?Why Software Defined Radios?

! Dale Hatfield, WØIFO,Chief, Office of Engineering and Technology,Federal Communications Commission

“This could stimulate a whole new generation ofamateur innovation that not only includes themore spectrally efficient systems I mentionedearlier, but also radios that could adapt to theirenvironment as well.”

Speech to AMRAD’s 25th Anniversary Dinner June 17, 2000

http://www.fcc.gov/Speeches/misc/dnh061700.html

What Is a Software Defined Radio?What Is a Software Defined Radio?

Software Defined Radio (SDR)

Performs the majority of signal processing in thedigital domain using programmable DSPs andhardware support, but some signal processing is stilldone in the analog domain, such as in the RF and IFcircuits.

What Is a Software Defined Radio?What Is a Software Defined Radio?

Software Radio (SW)

The ultimate device, where the antenna is connecteddirectly to an A-D/D-A converter and all signalprocessing is done digitally using fullyprogrammable high speed DSPs. All functions,modes, applications, etc. can be reconfigured bysoftware.

Benefits of SDRBenefits of SDR

! Flexible

! Reduced Obsolescence

! Enhances Experimentation

! Brings Analog and Digital World Together

New Breed of RadioNew Breed of Radio

! Reprogrammable

! Multiband/Multimode

! Networkable

! Simultaneous voice, data, and video

! Full convergence of digital networks and radioscience.

Block DiagramBlock DiagramSoftware Defined RadioSoftware Defined Radio

VariableFrequencyOscillator

LocalOscillator

(fixed)

Antenna

BandpassFilter

RF IF Baseband

ADC/DACDSP

Block DiagramBlock DiagramSoftware Defined RadioSoftware Defined Radio

LocalOscillator

(fixed)

AntennaRF IF Baseband

DSPADC/DAC

Block DiagramBlock DiagramSoftware RadioSoftware Radio

AntennaRF IF Baseband

DSPADC/DAC

Smart RadiosSmart RadiosThe positive control over the transmitter’s use of thespectrum has traditionally been the purview of theradio operators, who were guided and trained tofollow the rules of engagement carefully craftedduring the course of decades to prevent harmfulinterference to other users.

The control of radio functions by softwarealgorithms embedded into the future “smart”communications device will directly affect themanner in which that device uses the spectrum.

Smart RadioSmart Radio

! When combined with the software radio’s abilityto monitor the RF environment and preciselysense its location, the software radio opens thepossibility of sharing spectrum among vastlydifferent users.

What Is a Software Defined Radio?What Is a Software Defined Radio?

Cognitive Radio

As radios embed increasingly complex and realisticmodels of their environments, users, and networks,they begin to approach what an outside observermight call rational, or common-sense behavior.

Technical ChallengesTechnical Challenges

! Dynamic Radio

! ADC/DAC Speed

! Smart Radio Algorithms

Amateur ContributionsAmateur Contributions

How to Build a SDRHow to Build a SDR

! DSP-10 by Bob Larkin, W7PUAQST - Sep, Oct, Nov 1999

http://www.proaxis.com/~boblark/dsp10.htm

http://www.arrl.org/tis/info/vhfproj.html

! R2-DSP by Rob Frohne, KL7NAQST - Apr 1998

http://www.wwc.edu/~frohro/R2_DSP/R2-DSP.html

! A Panoramic Transceiving System for PSK31by Skip Teller, KH6TY and Dave Benson, NN1G

QST - Jun 2000

http://www.arrl.org/tis/info/psk31.html

The DSP-10 As a SDRThe DSP-10 As a SDR

DSP-10

Constructed byErnie Manly, W7LHL

TR SW(D2)

U1,U2

TR SW(D1)

U4,U5

Synthesizer124.3 to 128.4 MHz

5 kHz Steps

Synthesizer19.680 MHz

TR SW(U11A,U11C)

Q1,U10A

ADC 90o

Arc TangentFM Detector

Sinewave BFO12.5 -17.5 kHz

90o

SW

+ / - AGC

AudioFilters

LMSDenoise

DAC U14

FFT SpectrumAnalyzer

FMSquelch

SSB and CWDetector

Analog Devices EZ-Kit Lite

Speaker

Serial Datato PC

1024 Points

AudioPower Amp

IF Amp

50 dB

ANT orXVRTR

R

T

R

T

143 - 149 MHz

150 MHz

2-PoleLC Filter

Low-PassFilter

40 dB

TransmitRF Amp

ReceiveRF Amp

32 dB143 - 149 MHz 19.665 MHz

FirstMixer(U3)

SecondMixer(U15)

28 kHz

Low-Pass Filter4-PoleCrystal Filter

4-PoleLC Filter

TRSW

(U11B)

U109B,Q5,Q6

IF Driver

TR SW(U12A,U12B)

Microphone

R

T

T

R

R

PTT

CW Key

10 MHzExt. Ref.

(Optional)

10-20 kHz

J212

J213

J211

J102

J103

J201

J204

Receiver Second IF10-20 kHz

Supporting DocumentationSupporting Documentation

! Signals, Samples and Stuff: A DSP Tutorialby Doug Smith, KE6DX

QEX - Mar, May, Jul, Sep 1998http://www.arrl.org/tis/info/dsp.html

! Basics of Digital Receiver Designby Brad Brannon, N4RGI

QEX – Sep/Oct 1999

! A DSP-Based Audio Signal Processorby Johan Forrer, KC7WW

QEX – Sep 1996http://www.peak.org/~forrerj/ASP/article.html

ConclusionConclusion