Software Defined Radios Introduction to - qsl.net · Block Diagram Software Defined Radio Variable...
Transcript of Software Defined Radios Introduction to - qsl.net · Block Diagram Software Defined Radio Variable...
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