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

SDR Advances Agenda

What is an SDR? New Technologies in SDR

Direct Sampling SmartSDR Architecture Networking CESSB Wide and Narrow simultaneously

Future SDR Capabilities

What is an SDR?

What is an SDR?

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?

Back to Basics …

Radio Magic

Back to Basics …

LO

DEMOD

FILTER IF AMP

AUDIO AMP

MIXER

Multi-Conversion

64.455 MHz 455kHz

36kHz

3–15 kHz Roofing Filter

Distortion

DEMOD

Engineering Design Process

Draw a block diagram

Simulate

Draw a schematic

Simulate

Build

Measure and adjust

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

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

Components and ProblemsResistors Capacitors Inductors Transistors Mixers Amplifiers Crystals Filters

Lot Variance Parasitics Non-linearities Thermal variance Electrically induced variance IMD Manufacturing variance The list goes on…

Filtering: The Goal“Brick Wall” Filter

frequency

resp

onse

Block undesired

Pass desired

FilteringPractical limits to achievable results

Suggested capacitor model, Tantalum capacitor

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

Filter Design: SimulationSampled 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

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 DACFILTER SIMULATION

Presto: Software in the Radio

LO

DEMOD

FILTER IF AMP

AUDIO AMP

MIXER

FILTER

Is this an SDR?

ADC DAC

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

Filter Shape Factor

FLEX-5000 Note Brick Wall & Flatness

Radio Y

Radio Z

Radio X

500 Hz Brick Wall Filter

6dB Bandwidth 487 Hz, 60dB Bandwidth 660 Hz, Shape Factor ~1.35 4096 Bin FFT and 2048 Tap Filter

2.8KHz SSB Filter Spectrum

6dB Bandwidth 2587 Hz, 60dB Bandwidth 2756 Shape Factor ~1.06, 2048 Tap Filter

Software Demodulation

LO

DEMOD

FILTER IF AMP

AUDIO AMP

MIXER

FILTER

Now, is this an SDR?

ADC

DAC

Software Demodulation and Baseband

New demod schemes added later!

Precise Filtering

Advanced Noise Reduction

DEMOD

IF AMP

AUDIO AMP

FILTER DAC

ADC

PowerSDR - A FlexRadio Original!

Economics 101

What is the marginal cost of a 2nd receiverin an analog radio?

ANSWER: the cost of the added parts (plus amortized engineering)

What if I want 2 RX?

LO

DEMOD

FILTER IF AMP

AUDIO AMP

MIXER

FILTER

2x analog components ≈ $2x

ADC

DAC

DEMODADC

FILT

ER

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?

LO

DEMOD

FILTER IF AMP

AUDIO AMP

MIXER

FILTER

What about this analog stuff?

DAC

ADC

Direct Sampling

LO

DEMOD

FILTER

AUDIO AMP

MIXER

FILTER

Now, THAT’s an SDR!

DAC

ADC

LO

DEMOD

FILTER IF AMP

AUDIO AMP

MIXER

FILTER

Why doesn’t everyone do Direct Sampling?192kHz @ 64bits =

12Mbps192kHz

DAC

ADC

10Mbps

Direct Sampling

LO

DEMOD

FILTER

AUDIO AMP

MIXER

FILTER

Now, THAT’s an SDR!

250MHz @ 16bits = 4Gbps

250MHz

DAC

ADC

4Gbps is…

40 - 100Mbps cables4 - 1Gbps cables

That’s a LOT of data! The most modern home networking you can buy, can’t handle this …

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

Economics 101

What is the marginal cost of a 2nd receiverin an digital radio (SDR)?

ANSWER: the cost of the extra processing power (plus amortized engineering) … think Moore’s law

Processing Power = FPGA

Direct Sampling

LO

DEMOD

FILTER

AUDIO AMP

MIXER

FILTER

Now, THAT’s an SDR!

ALL of HF digitizedALL of HF

DAC

ADC

Direct Sampling

NCO

DEMOD

FILTER

AUDIO AMP

MIXER

How many do you want?

DAC

ADC

DEMOD

FILTER

MIXER

We are called to be the architects of the future, not it’s victims

—R. Buckminster Fuller

Design Options: #1: ADC and a hose

Radio is ADC ⟹ FPGA ⟹ Ethernet

Leverage PowerSDR; minimal SW investment

ADC FPGA PC

RADIO

CDRX-3200, circa 2008

32 Synchronous, Coherent ADCs + FPGA

440Mbps bandwidth

Our customers have trouble absorbing the bandwidth

ADC and a hose: CDRX-3200

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

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

Direct Sampling Radios

HPSDR Hermes

HPSDR

RF DSP DSP CTRL

ANAN-100D

Direct Sampling Radios

RF DSP CTRL

FLEX-6000

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

Spectrum Display BW

1MHz <500kbps

1MHz 77Mbps

150:1 Bandwidth Difference

10MHz <500kbps

1500:1 Bandwidth Difference

10MHz 770Mbps

Networking

EVERYTHING is moving to the network.

You can TAKE YOUR FUN WITH YOU

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

T32C

RF

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

T32C

RFInternet

What is a contact?You talk to Christmas Island using your local 2m repeater and EchoLink

T32C

RFInternet

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

T32C

RFInternet

Does your radio need THIS?

Does your radio run HERE?

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

Adaptive Predistortion

Power Amplifiers: Nonlinearities

Designs have improved

What if we knew in advance of the PA?

Could we correct?

HPSDR: Pure Signal

Predistortion Before

Predistortion After

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

Low Phase Noise Field Day

Low Phase Noise Field Day

100W PSK31

© 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

© 2 0 1 4 F L E X R A D I O S Y S T E M S

Speech Processor Power

Many data streams at once

FLEX-6700

8 narrow-band 24kHz receivers

8 panadapters

4 wide-band (192kHz) I/Q streams for skimming

Multi-mode Waterfall

Waterfall plus Bandscope

CW Skimmer x4

Digital Modes

More Functional Displays

WSPR times 4!

EasyPAL

TX6G: A Picture is worth 1,000 words

Remote Audio Coming in v1.4

Today: CW, PSK, RTTY

Tomorrow: Everything Digital and voice

Digital is fully integrated … no cables

The Future: Decoding

© 2 0 1 4 F L E X R A D I O S Y S T E M S

The Future: Decoding

Today: Mostly hacked together and inconvenient

Tomorrow: Easy remote, tablets everywhere

The Future: Remote

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

Today: Virtually none

Tomorrow: Radios will find and classify signals (determine mode)

The Future: Signal Classification

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

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

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

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