SDR technology is advancing in several areas. Direct sampling digitizes the entire HF spectrum and allows for unlimited receivers and panadapters. Networking allows operating from anywhere. Speech processing provides power improvements. Future capabilities may include signal classification, advanced noise reduction across antennas, and better integration of remote stations.

2. SDR Advances and the
Future of SDR
Pacificon: October 11, 2014
Stephen Hicks, N5AC
VP Engineering, FlexRadio Systems
F L E X R A D I O S Y S T E M S

3. SDR Advances
Agenda
What is an SDR?
New Technologies in SDR
Direct Sampling
SmartSDR Architecture
Networking
CESSB
Wide and Narrow simultaneously
Future SDR Capabilities

4. What is an SDR?

5. What is an SDR?

6. What is an SDR?
SDR is a spectrum
Some radios are clearly NOT
Other radios clearly ARE
Many permutations is-between
So what makes up an SDR?

7. Back to Basics …
Radio
Magic

8. Back to Basics …
LO
DEMOD
FILTER IF AMP
AUDIO AMP
MIXER

9. Multi-Conversion
64.455 MHz 455kHz
36kHz
3–15 kHz
Roofing Filter
Distortion
DEMOD

10. Engineering Design Process
Draw a block diagram
Simulate
Draw a schematic
Simulate
Build
Measure and adjust

11. Engineering Design Process
Does the circuit match the simulation exactly?
NO … WHY?
Components are not “ideal”
There are losses not modeled
Component variance
Component capabilities
Result: Never as good as the simulation

12. Can’t we account for
component differences?
In some cases, YES
Some materials work better in some cases
Compensating circuits can be added
In some cases, NO
There will always be issues

13. Components and Problems
Resistors
Capacitors
Inductors
Transistors
Mixers
Amplifiers
Crystals
Filters
Lot Variance
Parasitics
Non-linearities
Thermal variance
Electrically induced variance
IMD
Manufacturing variance
The list goes on…

14. Filtering: The Goal
“Brick Wall” Filter
frequency
response
Block undesired
Pass desired

15. Filtering
Practical limits to achievable results
Suggested capacitor model, Tantalum capacitor

16. Block Diagram Key
Yellow blocks are
Green blocks are DIGITAL
ANALOG
123
346
767
1134
001
1010
1011
110
010
455
913
21
2394
23

17. Filter Design: Simulation
Sampled signals passed through simulated ideal
components
Results could even be played out a speaker
123
346
767
1134
1582
1204
895
431
208
150
300
600
1200
1500
1200
600
300
150
FILTER
SIMULATION
DAC

18. Filter Design: Simulation Limits
Analog: 20-30 poles
Digital: unlimited … except for latency.
Maybe 200, 1000, more!
Could a computer run the simulation IN THE RADIO?
ADC DAC
FILTER
SIMULATION

19. Presto: Software in the Radio
LO
DEMOD
FILTER IF AMP
AUDIO AMP
MIXER
FILTER
Is this an SDR?
ADC DAC

20. DEFINITIONS:
Software Defined vs. Controlled
CONTROLLED
Computer Control of Fixed Capabilities
(frequency, band, etc)
DEFINED
Modulation, Demodulation, filtering, and processing; as
well as Control Capabilities Software Defined and
Upgradeable

21. Filter Shape Factor
FLEX-5000
Note Brick Wall & Flatness
Radio Y
Radio Z
Radio X

22. 500 Hz Brick Wall Filter
6dB Bandwidth 487 Hz, 60dB Bandwidth 660 Hz, Shape Factor ~1.35
4096 Bin FFT and 2048 Tap Filter

23. 2.8KHz SSB Filter Spectrum
6dB Bandwidth 2587 Hz, 60dB Bandwidth 2756
Shape Factor ~1.06, 2048 Tap Filter

24. Software Demodulation
LO
DEMOD
FILTER IF AMP
AUDIO AMP
MIXER
FILTER
Now, is this an SDR?
ADC
DAC

25. Software Demodulation and
Baseband
New demod schemes
added later!
Precise Filtering
Advanced Noise
Reduction
DEMOD
IF AMP
AUDIO AMP
FILTER DAC
ADC

26. PowerSDR - A FlexRadio Original!

27. Economics 101
What is the marginal cost of a 2nd receiver
in an analog radio?
ANSWER: the cost of the added parts (plus
amortized engineering)

28. What if I want 2 RX?
LO
DEMOD
FILTER IF AMP
AUDIO AMP
MIXER
FILTER
2x analog components ≈ $2x
ADC
DAC
DEMODADC
FILTER

29. What are we trying to achieve?
Remove distortion
Better performance
Flexibility to change or add features
Ability to tailor the radio quickly
Never before possible noise mitigation
Never before possible capabilities
Can we do more?

30. LO
DEMOD
FILTER IF AMP
AUDIO AMP
MIXER
FILTER
What about this analog stuff?
DAC
ADC

31. Direct Sampling
LO
DEMOD
FILTER
AUDIO AMP
MIXER
FILTER
Now, THAT’s an SDR!
DAC
ADC

32. LO
DEMOD
FILTER IF AMP
AUDIO AMP
MIXER
FILTER
Why doesn’t everyone do Direct Sampling?
192kHz @ 64bits =
12Mbps
192kHz
DAC
ADC

33. 10Mbps

34. Direct Sampling
LO
DEMOD
FILTER
AUDIO AMP
MIXER
FILTER
Now, THAT’s an SDR!
250MHz @ 16bits =
4Gbps
250MHz
DAC
ADC

35. 4Gbps is…
40 - 100Mbps cables
4 - 1Gbps cables
That’s a LOT of data!
The most modern home networking you can buy, can’t handle this …

36. Direct Sampling Benefits
+ Distortion minimized (ADC @ antenna): best signal clarity
+ n-Receivers, n-Panadapters and varying widths
see more bands, more receivers
+ Extremely high dynamic range: operate in worst
conditions
+ Extreme flexibility through reprogrammability (ultimate
SDR): future benefits
– Technically challenging to design

37. Economics 101
What is the marginal cost of a 2nd receiver
in an digital radio (SDR)?
ANSWER: the cost of the extra processing power
(plus amortized engineering) … think Moore’s law
Processing Power = FPGA

38. Direct Sampling
LO
DEMOD
FILTER
AUDIO AMP
MIXER
FILTER
Now, THAT’s an SDR!
ALL of HF digitizedALL of HF
DAC
ADC

39. Direct Sampling
NCO
DEMOD
FILTER
AUDIO AMP
MIXER
How many do you want?
DAC
ADC
DEMOD
FILTER
MIXER

40. We are called to be
the architects of the future,
not it’s victims
—R. Buckminster Fuller

41. Design Options:
#1: ADC and a hose
Radio is ADC ⟹ FPGA ⟹ Ethernet
Leverage PowerSDR; minimal SW investment
ADC FPGA PC
RADIO

42. CDRX-3200, circa 2008
32 Synchronous, Coherent ADCs + FPGA
440Mbps bandwidth
Our customers have trouble absorbing the bandwidth
ADC and a hose:
CDRX-3200

43. LBRX-24, circa 2010
24 Microwave ADCs + 2 FPGAs
40Gbps bandwidth, yes Gigabit, 4x10Gb SFP+
Our customers’ PCs have memory in the 100s of GB
ADC and a hose:
LBRX-24

44. RADIO
Design Options:
#2: ADC + FPGA + DSP/uP
Radio reduces bandwidth to minimum before Ethernet
Oh gosh: start over with SW: big investment!
ADC FPGA
PC/
OTHER
CHL
BB
DSP

45. Direct Sampling Radios
HPSDR
Hermes
HPSDR
RF DSP DSP CTRL
ANAN-100D

46. Direct Sampling Radios
RF DSP CTRL
FLEX-6000

47. Integrating the Baseband Processor
Key Benefits
Consistent performance independent of PC
Minimized network bandwidth (think remote)
Minimization of “system” problems
Self-contained, rapid startup platform
Spectrum displays (panadapter) independent of
available network bandwidth
Network optimized

48. Spectrum Display BW
1MHz
<500kbps
1MHz
77Mbps
150:1
Bandwidth
Difference
10MHz
<500kbps
1500:1
Bandwidth
Difference
10MHz
770Mbps

55. Networking
EVERYTHING is moving to the network.
You can TAKE YOUR FUN WITH YOU

56. What is a contact?
You’re at your QTH and you work Christmas Island
T32C
RF

57. What is a contact?
You’re trade emails with the operator of T32C on
Christmas Island. His email says “You are 599 here!”
T32C
RF
Internet

58. What is a contact?
You talk to Christmas Island using your local 2m
repeater and EchoLink
T32C
RF
Internet

59. What is a contact?
You’re at the store and you remote control your home
station to work Christmas Island
T32C
RF
Internet

60. Does your radio need THIS?

61. Does your radio
run HERE?

62. T/F: Rare DX is convenient
Where’s your operating position?

63. Adaptive Predistortion
Power Amplifiers: Nonlinearities
Designs have improved
What if we knew in advance of the PA?
Could we correct?
HPSDR: Pure Signal

64. Predistortion
Before

65. Predistortion
After

66. Phase Noise
Affects both RX and TX interference capabilities
Oscillator phase noise getting better every year
Direct Sampling radios demanding
Take a look at the all FLEX-6000 Thunderbird FD

67. Low Phase Noise
Field Day

68. Low Phase Noise
Field Day
100W PSK31

69. © 2 0 1 4 F L E X R A D I O S Y S T E M S
Speech Processor (CESSB)
David Hershberger, W9GR,
approached us at Dayton 2013
Algorithm implemented in
SmartSDR + on-air testing
Excellent speech and a ~2.5dB
power improvement
Results and algorithm to be
published in QEX later this year

70. © 2 0 1 4 F L E X R A D I O S Y S T E M S
Speech Processor Power

71. Many data streams at once
FLEX-6700
8 narrow-band 24kHz receivers
8 panadapters
4 wide-band (192kHz) I/Q streams for skimming

72. Multi-mode Waterfall

73. Waterfall plus Bandscope

74. CW Skimmer x4

75. Digital Modes

76. More Functional Displays

77. WSPR times 4!

78. EasyPAL

79. TX6G: A Picture is worth 1,000 words

80. Remote Audio
Coming in v1.4

81. Today: CW, PSK, RTTY
Tomorrow: Everything Digital and voice
Digital is fully integrated … no cables
The Future:
Decoding

82. © 2 0 1 4 F L E X R A D I O S Y S T E M S
The Future:
Decoding

83. Today: Mostly hacked together and inconvenient
Tomorrow: Easy remote, tablets everywhere
The Future:
Remote

84. Today: On premise integration driven by contesters
Tomorrow: Integration driven by plethora of remote
solutions and the need to drive other hardware
The Future:
Integration

85. Today: Virtually none
Tomorrow: Radios will find and classify signals
(determine mode)
The Future:
Signal Classification

86. Today: Phased receive arrays, few TX arrays
Tomorrow: Every antenna will have an SCU and for
operators with multiple antennas, instant arbitrary,
rotation will be possible
The Future:
Steering and MIMO

87. Today: Panadapters, Waterfalls and the occasional
scope
Tomorrow: New displays that show perspectives of
data not previously seen. Operational advantage will
drive innovation
The Future:
Visualization

88. Today: Advanced NB, NR techniques in many radios
Tomorrow: Dedicated noise receivers will be used to
eliminate noise more effectively, optimal combining
across multiple antennas will emerge
The Future:
Noise Reduction

89. Today: Occasional Remote-to-base operation
Tomorrow: Remote assets will be combined inside of a
single program to enhance operational capabilities.
Remotes may be used in combining, DFing or other
applications
The Future:
Networking