Transcript Quantum Software Defined Radio

Software Defined Radio
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Why build an SDR
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Reduces amount of hardware needed
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Easy to add new features since they are all done in software.
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Transmit/receive filters, Power amp,1st stage receive & transmit mixer
Parts are readily available
Filters can be dynamic, easy to add new ones, often better than what
can be done in hardware.
New operating modes
New operating bands, when they become available (with in limitations
of hardware filters)
Performance can be comparable if not better than commercial rigs
Just for the fun of it….
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Quantum Software Defined
Radio
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Hardware Architecture
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Software Architecture
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Overview, Features & Flow
Demodulation & Modulation Algorithms
SDR Operation
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Overview, Features & Flow
Board schematics & photos
Decoder SPICE Simulations
Encoder SPICE Simulations
AM & SSB photos
To Do list
Demo
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Hardware Overview
Band Filter
Selection
10/20db Amp
& TX/RX
USB based
Controller
VFO
0.5-54Mhz
Filters
Pre-Selector RX
Preamp, 1st TX Amp
Power Amp
Quadrature
Encoder /
Decoder
I/Q Audio
to PC, I/Q
From PC
RF In/Out
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Hardware Features
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USB interface
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< 1 Hz steps possible
Off the shelf parts
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Can be interfaced to Windows, LINUX and MAC without drivers
RX gain adjustable on decoder & will add preamp to pre-selector
Ham band filters to be used in the pre-selector
500KHz to 54MHz continuous
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Controller acts as low speed HID device
Most parts available from Digikey or Mouser
DDS available direct from Analog Devices, Transformer from MiniCircuits
PI5V331 from All American Direct (min $50 order)
Low phase noise, low noise DDS (AD9854) used (< -100 dbm,<25 pS rms jitter).
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Low phase noise, low noise 72MHz oscillator used ,4x PLL used on DDS to raise internal clock to 284MHz @ the
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DDS (AD9854) simplifies hardware by providing I & Q clock signal for encoder & decoder clock
expense of an extra 350mA.
Designed to function as 2 Receiver, 1 Transmitter radio
Will add >40db gain exciter to drive PA
Receiver sensitivity measured @ ~ -115dBm (10db S/N)
VFO & image signals ≤ -50dB from signal during transmit
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Hardware flow
RX
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Incoming RF is filtered by pre-selector.
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Decoder performs sample/hold, breaks signal in to 4 phases, mixing signal to
audio range.
0o & 180o phases differentially added to make I, 90o & 270o phases
differentially added to make Q
‘Mixer’ adds 1-2db gain
High Q
f
Q
Bandwidth set by
c
BW
BW  4 Rant C s 
1
Instrumentation amps add 10db/20db more gain
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1:4 transformer before decoder adds 12db gain
Overall RX gain measured to be about 23db (with 10db from Instrumentation
amps)
PC performs A/D, filtering, demodulation, AGC, squelch & etc
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Hardware flow
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TX
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PC performs modulation, filtering, compression &
leveling & etc, Creates I & Q, D/A
DRV135 driver buffers/adds 6db of gain to
compensate for 4:1 transformer
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Creates 0o, 90o, 180o & 270o phases from I/Q
Encoder mixes signal up to RF range set by VFO
frequency.
Signal filtered & amplified to get enough drive for
PA
Signal further amplifier & filtered before radiated
into the ether
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Controller Schematic
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VFO Schematic
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Encoder/Decoder Schematic
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T im e (s )
Tay loe-2-Transient-0-Graph
550.000u
600.000u
650.000u
700.000u
750.000u
800.000u
850.000u
900.000u
950.000u
1.000m
-1.000m
0.0
v(25)
-200.000m
(V)
0.0
v(quadrature)
(V)
0.0
v(inphase)
(V)
Spice RX Simulations 1.01MHz Carrier, 2.5 KHz Modulation, VFO @
1.0 MHz ( I & Q output + 800uV rms AM incoming signal shown)
TIME
865.307u
D(v(25))
0.0
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v(inphase)
222.929m
v(quadrature)
-21.920m
v(25)
-215.490u
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D(TIME)
0.0
10
Spice RX Simulations 1.01MHz Carrier, 2.5 KHz Modulation, VFO @
1.0 MHz ( I & Q output + 800uV rms AM incoming signal shown)
T i m e (s )
Tay loe-2-Transient-0-Graph
600.000u
650.000u
700.000u
750.000u
800.000u
850.000u
900.000u
950.000u
1.000m
-200.000m
-100.000m
0.0
100.000m
200.000m
(V)
550.000u
TIME
865.307u
D(v(25))
0.0
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v(inphase)
222.929m
v(quadrature)
-21.920m
v(25)
-215.490u
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D(TIME)
0.0
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Measured SDR Decoder Response
1Mhz Carrier
10 Mhz Carrier
Measured Decoder Response
Offset From -87dBm Carrier (KHz)
-50
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
-52
Amplitude (dBm)
-54
-56
-58
-60
-62
-64
-66
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Measured Encoder Response
Encoder Signal & Image Strength
0
Strength(dBm)
2
4
7
-20
10
1 4 1 8 .1
2 1 2 4 .9
28
29
54
-40
-60
-80
-100
Frequency (Mhz)
VFO
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Signal
Image
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Spice TX Simulations: 1.0MHz VFO, 0.3VRMS, 2.5 KHz Modulation (
4 phase inputs to PI5V331 & RF signal shown)
T im e (s )
Tay loe-TX-AM-Transient-0-Graph
550.000u
600.000u
650.000u
700.000u
v(n1)
644.215m
750.000u
800.000u
850.000u
900.000u
950.000u
1.000m
(V )
2.000
1.500
1.000
500.000m
0.0
TIME
598.474u
v(VRF)
-225.801m
D(TIME)
1.105u
D(v(n4))
-4.449m
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v(n2)
677.804m
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v(n3)
2.129
v(n4)
535.692m
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VFO Board
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VFO Board
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VFO Board
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Encoder/Decoder Board
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Encoder/Decoder Board
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Program Architecture
Wave File (I & Q) data
Sound
Class
I &Q from
decoder to Line In
Stere
o
Audio
UI Class
Mono Audio
Speakers
Signal
Processing
Class
Settings stored
by band & mode
Wave
Volume
& Input
Gain
Filter Settings Class
Mixer Class
Filter Settings File
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Software flow (Receive)
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IF signal is digitized by the Sound card, @ 44.1Khz, 16bit/sample stereo (for I & Q)
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Previous data set spectrum data is plotted
FFT, converts to polar coordinates.
IF shifted by 11.025KHz, zero out unused side band
Band Pass & Notch filters applied
Data ‘thinned’ and saved for plotting
Translate back to Cartesian, Inverse FFT
Audio processing
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Data sampled in 2048 bytes, 10.7Hz resolution
Program converts data to ‘double’ for numerical processing
Demodulation
Squelch, AGC & Noise filtering
Audio data is converted back to integer and sent to sound card for playback
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Playback buffer buffered by 1 sample so total delay is 92 mS
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Software Features/Requirements
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Uses Readily available (free) libraries & tools
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Any mode that can fit in to 15KHz bandwidth can be RX’d / TX’d
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Limitation of 1/f noise, depending on where IF is defined
Easy to add new bands & operating modes
Digital Filters offering, adjustable BW, sharp contours, user configurable
Capture & play back OTA signals in I & Q form.
Software could support 2 receivers boards
Real time color coded Spectrum analyzer
Control of sound card input gain and output volume
Adjustable AGC & Squelch
In band split operation
Memories
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DirectX 8 SDK, Windows Device Driver DDK (for USB HID library)
Digital Mars D Compiler (free www.digitalmars.com)
Intel NSP Library (free for non commercial use)
Requires ~ 800MHz P3 or better
Saves filter & mode settings for each memory entry
Control over pre amplifier stages
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Features currently implemented
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Hardware
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USB controller, 1 VFO
1 Receiver, 1 Transmitter
Decoder pre-Amp
Software
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AM, FM , LSB, USB, CW receive
AGC
Adjustable band pass, 2 notch filters (in the frequency domain), LMS &
Noise filters (in the time domain)
Input gain and output volume control
Colour coded spectrum graph of incoming filter (post band pass & notch)
Save I & Q data to wave file and playback I & Q data from wave file
Custom controls for knob, LCD display, graph, multiple slider control
Squelch algorithms for FM & non FM modes
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FM – Decision based upon Mean of demodulated audio
Other Modes - Decision based upon Stdev of demodulated audio
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Receive Algorithms
AM
A  I Q
2
2
SSB
Q
 Q  /4
USB
 I Q
/
LSB
 I Q
/
A
A
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/
(Hilbert Transform)
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Receive Algorithms
FM (Digital Differentiator)
I  I I Q Q
Q Q I  I Q
'
n 1
n
n 1
n
'
n
(1st
&
n 1
4th
n
n 1
1
quadrant) A  tan (Q / I )
'
'
(2nd quadrant)
A   tan (Q / I )
(3rd quadrant)
A  tan (Q / I )  
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1
1
'
'
'
'
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Software Flow (Transmit)
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Mike input sampled@ 44.1Khz, 16bit, mono.
Data sampled in 2048 bytes, 10.7Hz
resolution
FFT, converts to polar coordinates.
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Band Pass applied, Signal leveling/Compression
Signal Modulated & IF shifted by 11.025KHz
Translate back to Cartesian, Inverse FFT
I & Q signals sent to Encoder
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Transmit Algorithms
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AM
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SSB
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DC offset applied to signal to make carrier
FFT, convert to Polar, BP filtering, IF Shift & etc
Convert to Cartesian,
Inverse FFT forms I & Q signal
FFT performed, convert to Polar, zero out unwanted
sideband, BP filtering, IF shift & etc
Convert to Cartesian,
Inverse FFT forms I & Q signal
CW & FM
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Haven’t got around to it yet…..
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AM - WMEL
(attempted minimize signal strength)
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20M SSB
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To Do List
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Receive
 Split operation
 Data modes: PSK31, RTTY, SSTV, Digital Voice
 Better LF filter before sound card to remove strong
signal images ?
 ‘Noise free’ CW reception
Pre- selector
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Narrow Filters for each band (including 60m)
Add ~10 db pre-amp (MiniCircuits GALI series?)
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Add >40db exciter (GALI series + power FET)
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To Do List (Cont)
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TX
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CW,FM, PSK31,SSTV, RTTY Digital Voice
Power Amp
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Filters for PA
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Overall
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Integrate VFO and Enc/Dec into 1 board, get rid of higher frequency layout effects
Integrate filtering on DC/DC converter in to board
Higher speed OSC on VFO to reduce current/heat (156 MHz LVPECL from Crystek)
Make same form factor if possible as pre-selector
Complete the UI
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Also available from Communications Concepts (except 60 & 6m)
Look at Encoder/Decoder/VFO re-layout
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Probably will buy from Communications Concepts (1-5W in, 140w out)
Look Griffin USB Knob for VFO control
Make a nice cabinet
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