Software Defined Radio (SDR) and its Implementation Brandon Graham W0GPR
Dec 19, 2015
Software Defined Radio (SDR) and its Implementation
Brandon GrahamW0GPR
What is SDR
• Instead of relying on RLC circuits, a raw, lightly filtered analog signal is converted to the digital domain to be further processed by digital systems
• RF Front End ADC/DAC Computer
R.F.Front End
High QualitySound Card
P.C., Laptop,Netbook, orEmbeddedprocessor
Antenna
I,Q
I,Q
Digital vs Analog
Digital• Discrete• Digital Signal Processing
DSP• Filtering• Phase• Frequency• Time• Power
Analog• Continuous• Filtering• Power amplifier
Flex Radio
• Manufacturer of SDRs for Industry, Military and Amateur use starting in 2003
• HF transceivers ranging from QRP to 100 watts– Flex 1500 – QRP/transverter IF– Signature series – Contest serious radio– *Flex 3000– *Flex 5000– *SDR 1000• *discontinued
“The Feel of the Radio”
“The Feel of the Radio”
Power SDR
• Graphical User Interface (GUI)– Radio’s buttons and knobs
• Signal Processing– Filtering, DSP, Audio input and output shaping, etc
• Rig control– Frequency, band, tuner
• Program interface– VSPs, VACs, out to digital modes, logging, ext. aux
“The Feel of the Radio”
“The Feel of the Radio”
Computer system/Software
• VAC– Virtual Audio Cable
• VSP Manager– Virtual Com/Serial Port
• Com-0-Com• DDU Til• Logging• Digital Mode Program• Remote Operation
• Processor• RAM• Screen usage• Quirks
The system setupFlex 3000
PowerSDR
VAC
DDU Til
VSP Manager
FL-DIGI
WSJT-X
N1MM+
Computer
Com SingleVAC Pair 1VAC Pair 2FireWire
Pros / Cons of SDR over Analog
• Pros• Filter visualization• Filter manipulation• Control of settings• Visually based displays– Panafall, etc.
• DSP systems and control
• Cons• Quirky• Visually demanding• Computer intensive• Software setup• Need for multiple
monitors and mouse• Not EmComm Ready
“Let’s Play Radio”
Remote Operation
• Controlling computer, not radio
• Everything must be powered up at radio and ready for control
• Easier with digital over voice modes
• Lag• Control of accessory
programs and screens
WebSDR
• University of Twente– Netherlands
• Website designed for internet linked SDR receivers
• Mostly centered on ham bands.
• http://websdr.ewi.utwente.nl:8901/
• http://www.websdr.org/
Other SDR Systems
• $20 Dongle– Nooelec.com
• SDR SoftRock• HPSDR• ANAN• Genesis Radio• Rfspace
• Google is a friend!• Always New stuff added• Experimentation vs.
“Solid Systems”• Many different
programs• http://
www.abrohamnealsoftware.com/products.php?cat=10