Re: Low cost hardware option

GNU Radio
1

Hi,

I am interested in helping out with making some new gnuradio hardware
that is compatible with the USRP daughterboards. I worked with Matt
doing CAD on the original gnuradio project hardware and have since then
made lots more boards including a cyclone 3 board.

Here is a possible hardware configuration:
USB 3.0 transceiver IC or USB 3.0 microcontroller
Altera Cyclone3 FPGA
highspeed DAC/ADC

If we use just a single channel ADC and DAC (ie half a USRP v1) then we
can get away with a smaller/cheaper FPGA and have a cheaper/simpler
board that can be paralleled if needed (ie. two boards hooked up to USB
3.0)

Also we should pick a good open hardware license, here is one
possibility I came across:
http://freedomdefined.org/OSHW_draft

I do all my work with Eagle CAD, and they sponsored a license for the
gnuradio hardware project before, so we could look into getting a
gnuradio specific license again or else consider using a free CAD
program.

Here’s an eagle cad board I made with a cyclone3 FPGA on it designed to
interface to a powersupply:

http://rocketresearch.org/new/FPGA%20control%20module/FPGA%20control%20module%20PCB.png

cheers,
Jamie

[Discuss-gnuradio] Low cost hardware option

From:

Euripedes Rocha Filho

Subject:

[Discuss-gnuradio] Low cost hardware option

Date:

Wed, 12 Jan 2011 19:03:17 -0200

Hi, i’m watching all discussion about poor students and the evil Mr
Ettus who don’t play like Santa Claus and whant to make some profit :).
I’m also watching all topics and discussion regarding a low cost
solution for use with GNURADIO. I guess we can have a cheap option to us
and I’m very interested in work in such a solution. What I’m suggeting
here is to take all people who want’s to take the job and start a small
project. I’m a embedded systems enthusiatic and was a “starving
student”, now I’m a starving engineer, since I’m unemployed, that have
some time to work on this project. The first question is: Ok, we need a
low cost solution with some possible applications but what are the
limits?

2

On Wed, Jan 12, 2011 at 8:36 PM, Jamie M. [email protected] wrote:

If we use just a single channel ADC and DAC (ie half a USRP v1) then we can get
away with a smaller/cheaper FPGA and have a cheaper/simpler board that can be
paralleled if needed (ie. two boards hooked up to USB 3.0)
The idea of USB3 is nice for the future, but I don’t think there are
enough peripherals out there yet to make a good board. I can’t really
find anything that’s not completely preliminary and somewhat cheap.
I’d like to propose what I think may be a good compromise.

Altera Cyclone IV EP4CGX15 FPGA, Analog Devices AD9861 MxFE, USB2
microcontroller (for reprogramming the FPGA) in an ExpressCard/34
format. The FPGA has a hard PCIe 1.1 x1 lane with a hard IP core for
PCIe connectivity. The PCIe interface has an extremely low latency
and pretty high throughput - ~200MB/sec full duplex (after overhead
and whatnot). The FPGA would be mostly empty since the PCIe core is
hard. If the F169 package is used, it should be compatible with up to
a EP4CGX30 which would give 80 18x18 multipliers and over 1Mbit of
embedded memory. The ExpressCard format can fit into desktop PC’s
with simple and cheap adapters, or into laptops which have ExpressCard
slots.

ExpressCard has both an x1 PCIe connection as well as a USB 2.0
connection. I imagine a small USB 2.0 micro used for FPGA
configuration and, possibly, a secondary way for samples to enter/exit
the FPGA for different use cases (similar to the original USRP). But
the main purpose would be for reconfiguration of the FPGA.

Frequency synthesis can be an optional part of the assembly. I
imagine a relatively inexpensive VCTCXO (2ppm accuracy?) along with an
Si5338 clock synthesis chip. The idea, though, is to be completely
optional for those who really want it. Otherwise, the FPGA PLL’s can
probably be good enough for most people.

For connectors, 2 HDMI (commodity and cheap, twisted pair, shielded
and rated to relatively high frequencies) - one for analog/baseband
signals, one for digital I2C/SPI comms. Goes to a daughterboard
carrier which can hold the daughterboard and a digital IO port
expander for controlling the RX/TX IO [0:15] pins for the db
connectors.

I think the high bandwidth, low latency, and low CPU utilization of
PCIe is very attractive. The main downside to the parts are the BGA
components which can be daunting for hobbyists, but toaster ovens with
PID controllers can really do a pretty amazing job. I’m not sure if
this is a dealbreaker or not.

I’m very interested to hear other people’s opinions as to proposed
interfaces, platforms, architectures, and connectivity.

Jamie, I hope you don’t see this as a hijacking of your original
e-mail. I am particularly interested in your response.

Brian

3

On Wed, Jan 12, 2011 at 10:26 PM, Marcus D. Leech [email protected]
wrote:

embedded memory. The ExpressCard format can fit into desktop PC’s
imagine a relatively inexpensive VCTCXO (2ppm accuracy?) along with an
o it’s noisy in there!
Agreed on PCIe, though I think less platforms have USB3.

When speaking of noise at baseband (2V driving 50Ohms), assuming you
have a little can over the analog bits, is the noise that high?

Brian

4

On 01/12/2011 10:01 PM, Brian P. wrote:

with simple and cheap adapters, or into laptops which have ExpressCard
Si5338 clock synthesis chip. The idea, though, is to be completely
optional for those who really want it. Otherwise, the FPGA PLL’s can
probably be good enough for most people.

There are a couple of downsides to a PCIe implementation that I can
think of:

o not all host platforms are going to have PCIe slots
o it’s noisy in there!

The upside, as you point out, is that it’d be high bandwidth into the
host.

–
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

5

On 01/12/2011 10:46 PM, Brian P. wrote:

Agreed on PCIe, though I think less platforms have USB3.

Almost certainly the case right now.

When speaking of noise at baseband (2V driving 50Ohms), assuming you
have a little can over the analog bits, is the noise that high?

Not sure–somebody should take some measurements.

I’m increasingly liking the approach where you “demarc” at the digital
output of the ADC that I suggested
earlier where you terminate in something like a LPC-FMC connector or
something equally
convenient, which allows you to adapt to various “getting bits to the
host” approaches. Including:

 o 1GiGe
 o USB-2.0
 o USB-3.0
 o PCIe

But maybe that’s the road to more expensive, not less (although cost
is only ONE of the factors
of a project like this).

–
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

6

The idea of USB3 is nice for the future, but I don’t think there are
latencyand pretty high throughput - ~200MB/sec full duplex

with an
connectors.
I’m very interested to hear other people’s opinions as to proposed
interfaces, platforms, architectures, and connectivity.

Jamie, I hope you don’t see this as a hijacking of your original
e-mail. I am particularly interested in your response.

Hi Brian,

That sounds like a pretty good system. I should say right off the bat
that if I am involved to make this I would want to add a clause in the
open source hardware license to not allow the hardware to be used for
military applications. I think it is important to state this at the
start before I would get involved working on a new gnu radio board. If
people can live with that requirement I am happy to do the layout work.

cheers,
Jamie

7

Jamie-

8

On Jan 12, 2011, at 9:17 PM, Jamie M. wrote:

That sounds like a pretty good system. I should say right off the bat that if I
am involved to make this I would want to add a clause in the open source hardware
license to not allow the hardware to be used for military applications. I think
it is important to state this at the start before I would get involved working on
a new gnu radio board. If people can live with that requirement I am happy to do
the layout work.

How would you define “military applications”? I collect surplus military
gear as a hobby, and I’m presently working on a GNUradio-based
implementation of a decoder for high-speed Morse code transmissions from
my vintage AN/GRA-71 code-burst keyer (for which key pieces of the
original reception hardware is unobtainium). I’m presently working
entirely in simulation, but my USRP will get pressed into service for
this before long. Would you consider that application to be “military”?
Or how about if I were to use the hardware to intercommunicate with
other military radio hardware (such as any of the countless surplus
military radios used on the ham radio bands every day)? What if I throw
it in my HMMWV and use it on a ham band during a Veteran’s Day parade?
What if a soldier wishes to use the hardware on-base for MARS
activities?

If any such things would be considered “military”, then I’d neither use
nor contribute towards any hardware that’s shackled by such a silly
restriction. Furthermore, I doubt very much that the restriction would
be at all enforceable.

Personally, I don’t think that any prior restraint placed upon end use
of the hardware (beyond the requirement to keep derivative works open in
most cases) is compatible with the very libertarian principles of the
open software movement. I’ve released code under GPL. I thus place
certain limited restrictions on the use of the code to keep it open, but
beyond those limited restrictions, it’s really none of my business to
tell people what they can and can’t do with it. If I wanted to control
its end use to that degree, then I wouldn’t have released it in the
first place.

–
Mark J. Blair, NF6X [email protected]
Web page: http://www.nf6x.net/
GnuPG public key available from my web page.

9

On 13.01.2011 02:36, Jamie M. wrote:

I am interested in helping out with making some new gnuradio hardware that is
compatible with the USRP daughterboards. I worked with Matt doing CAD
on the original gnuradio project hardware and have since then made lots more
boards including a cyclone 3 board.

So, you’re a real expert on Gnuradio hardware … Great!

Also we should pick a good open hardware license, here is one possibility I came
across:
OSHW draft - Definition of Free Cultural Works

Good. It’s a bit like the LGPL. It allows also to combine open-source
with closed-source. The GPL-way would be too strict, because practically
you
can’t ban closed-source components from a complex PCB.

I do all my work with Eagle CAD, and they sponsored a license for the gnuradio
hardware project before, so we could look into getting a gnuradio
specific license again or else consider using a free CAD program.

Even if Eagle has more capabilities, I think it would be cool to use the
GNU-tool “gEDA” to create a Gnuradio-Hardware. So it would be a complete
GNU
world, from hard- to software. I didn’t use gEDA before. Would it be
possible to replace Eagle completely by gEDA (routing, EMI optimization,
Gerber
files, all CAM-relevant data)? Wasn’t the first USRP announced as a
demonstration of gEDA capabilities?

10

On 01/13/2011 02:00 AM, Jamie M. wrote:

All “non-commercial use only” clauses most likely restrict most military
use, and these are quite common, and are far more restrictive than a
“non-military use only” clause. I do follow what you are saying though, but its
a choice like “ethical investing”, it makes economic sense to some people and
seems foolish to some people.

Non-commercial use, academic only and other clauses restricting use of
the hardware/software in derived works is not compatible with the OSI
definition of an open source license. See:

Specifically, clause 6 states:

  1. No Discrimination Against Fields of Endeavor

The license must not restrict anyone from making use of the program in a
specific field of endeavor. For example, it may not restrict the program
from being used in a business, or from being used for genetic research.

Philip

11

----- Original Message -----
From: Jeff B. [email protected]
Date: Wednesday, January 12, 2011 9:43 pm
Subject: Re: [Discuss-gnuradio] re: Low cost hardware option
To: Jamie M. [email protected]
Cc: [email protected]

people can live with that requirement I am happy to do the
Can you show some examples of other successful open source /
open hardware projects where the license has this clause?

Hi Jeff,

All “non-commercial use only” clauses most likely restrict most military
use, and these are quite common, and are far more restrictive than a
“non-military use only” clause. I do follow what you are saying though,
but its a choice like “ethical investing”, it makes economic sense to
some people and seems foolish to some people.

cheers,
Jamie

12

FYI

Have a look at the article[1,2] from James Ahlstrom N2ADR [3]. I think
it could be an interessting approach/ point of start.

[1]
http://www.arrl.org/files/file/QEX_Next_Issue/Nov-Dec_2010/Ahlstrom%20NOV-DEC.pdf
[2] SSB Transceiver Software and Hardware
[3] http://james.ahlstrom.name/

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13

Jamie M. <jmorken shaw.ca> writes:

USB 3.0 transceiver IC or USB 3.0 microcontroller
Altera Cyclone3 FPGA
highspeed DAC/ADC

What about using an ASIC instead of the FPGA for the DDC, for example
AD6652
from Analog Devices, and connect that directly to the USB 3.0
Controller? Might
be cheaper?

http://www.analog.com/en/digital-to-analog-converters/digital-updown-converters/ad6652/products/product.html

  • ADF4350 for the Downconverter
  • AD6652 ADC and DDC
  • USB 3.0 Controller

You can always put a USB 3.0 Card in a PCI Slot if your Computer if it
does not
already have USB 3.0. It s not expensive.

Charly

14

I like this discussion. Perhaps we could talk to the folks at
http://www.oshwbank.org/ about helping sponsor the project (more
details:
Antipasto Hardware Blog: Introducing the Open Source Hardware Central Bank
)
Another idea would be to do a Kickstarter campaign to raise some initial
funds.
A platform like this for a hobby-accessible price would be fabulous for
education.
-William

15

On 14.01.2011 22:28, Charly Lima wrote:

What about using an ASIC instead of the FPGA for the DDC, for example AD6652
from Analog Devices, and connect that directly to the USB 3.0 Controller? Might
be cheaper?

http://www.analog.com/en/digital-to-analog-converters/digital-updown-converters/ad6652/products/product.html

DDC is a routine task and can be done in ASIC, that’s right.
However, i doubt that the ASIC can be attached directly to
USB controllers, because you have to handle the data bus,
control bus, controlling the frequency synthesizer.
I think in any case you need a FPGA as glue logic.
If the DDC is done in ASIC, the FPGA can be very small and cheap.

You can always put a USB 3.0 Card in a PCI Slot if your Computer if it does not
already have USB 3.0. It s not expensive.

USB 3 offers higher bandwidths than GiE, but GiE can be switched and
allows large distances. So I would prefer GiE if the bandwidth is
sufficient.
For higher bandwidths, 10GbE would be an option for future developments.

16

On 01/14/2011 04:28 PM, Charly Lima wrote:

What about using an ASIC instead of the FPGA for the DDC, for example AD6652
from Analog Devices, and connect that directly to the USB 3.0 Controller? Might
be cheaper?

The AD6652 isn’t exactly cheap, at $45.00 apiece. But I had also
considered that as a viable
option.

http://www.analog.com/en/digital-to-analog-converters/digital-updown-converters/ad6652/products/product.html

  • ADF4350 for the Downconverter
  • AD6652 ADC and DDC
  • USB 3.0 Controller

You can always put a USB 3.0 Card in a PCI Slot if your Computer if it does not
already have USB 3.0. It s not expensive.

YOu’d need a quadrature demod chip as well, like the ADL5387, which
takes in a 2XLO
(from the ADF4350).

Seems there’s lots of ways of doing this. A cheaper high-speed ADC +
cheap FPGA, or a more
expensive ADC with built-in DDC and CIC decimator, etc.

–
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

17

On 01/15/2011 07:45 AM, Patrick S. wrote:

o direct (embedded)
Any chance to transfer via eSATA? Quite common nowadays.

Maybe. Don’t know much about eSATA.

First, price is one constraint, or one of the features, that would make
such a device attractive to a wide audience. Others would be
flexibility, simpleness, that is fitness for home building,
capabilities: lowest/highest frequency, dynamic range, simultaneous
bandwidth, DDC, filtering, FPGA; RX only vs.s RX and TX; interface and
others.

For price: I’d say 200$-300$ for a tunable frontend, 16bit resolution,

I think $200.00 is a reasonable target for a RF front-end with
a digitized interface. Not sure about 16-bits, but certainly
14-bits.

I see the target for such at above all the soundcard solutions and below
the USRP1. USRP1 can do 8MHz Bandwidth complex at 14bit/sample RX, which
is more than enough for hobbyists. What would be interesting for
university teaching and research? What would be interesting for other
potential users, like hams? Did I miss some?

Small-scale radio astronomy (and other scientific radio applications)
require
bandwidth–lots of bandwidth, since radiometric sensitivity scales
with
sqrt(bandwidth). The large institutions have “in house” engineering
departments
who build all their own FPGA/ASIC “stuff” at staggeringly high
bandwidths.
(The Casper group is working on 3Gsps samplers). But smaller
endeavours,
down to the amateur level, don’t have the luxury or budget for that.
Since
radio astronomy is conducted all over the spectrum, having as wide a
tuning
range, to accommodate different bits of “science” is a benefit.

USB3.0 is common at new high end PCs and Laptops, ExressCard at Laptops.
Of course every PC with PCIe is ubgradable to both of them, but it’s
extra money to spend and extra hassle to get it started. I do not see
urgent need for such extreme data rates. This could be a second step.

20Msps can be done over USB-2.0, with suitable choice of data formats
“on the wire”, and you could probably do 40Msps over GiGe with
suitable choice of data formats.

–
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

18

On 15.01.2011 13:45, Patrick S. wrote:

For flexibility, being able to bypass stages or feed signals e.g. at the
ADC would be cheap. Preparing for different transport systems would make

I wonder how much noise will be introduced with a switch at the ADC.
At least I would use 2 different input connectors, because switching
in front of the LNA would surely introduce too much noise (except
some special shielded RF relays).

it more future proof. If USB3.0 hardware support is not satisfying now,
maybe it is in two years. For the data bus part this would require a
prepared interface for data and control lines.

At least the USB3.0 solution would be backwards compatible to USB2.
So it does not harm for older machines.

I see the target for such at above all the soundcard solutions and below
the USRP1. USRP1 can do 8MHz Bandwidth complex at 14bit/sample RX, which
is more than enough for hobbyists. What would be interesting for

Is this the limit? I was reading that the usable bandwidth (below line
speed)
is about 40 MB/s, so about 10 MS/s complex or 10 MHz baseband.
It’s not more than enough, but I could live with that restriction
(if it’s for a good low-cost compromise).

university teaching and research? What would be interesting for other
potential users, like hams? Did I miss some?

Yes, children and adult who like to play with electronics at home.
It could be an oscilloscope, spectrum analyzer, signal analyzer,
logic analyzer (ok, only 1 channel), signal recorder …
People who don’t make profit with it, have no university or tax-paxer
to finance the box … all those who can’t pay the price of $1000
for USRP (incl. tax, shipping, RF boards etc.)

For a start, a not too expensive, but still capable system with options
for extension seems most doable for me. If the transport systems is to
be fully integrated in the first shot, at least the data should be
accessible via some interface.

I agree to start not too expensive. The advantage of open-source
community
projects is, that it will be easy to modify the design later,
replace controllers, upgrade RF mixers or replace ADC by faster ones.

19

On 13.01.2011 02:36, Jamie M. wrote:

I am interested in helping out with making some new gnuradio hardware that is
compatible with the USRP daughterboards. I worked with Matt doing CAD
on the original gnuradio project hardware and have since then made lots more
boards including a cyclone 3 board.

I do all my work with Eagle CAD, and they sponsored a license for the gnuradio
hardware project before, so we could look into getting a gnuradio
specific license again or else consider using a free CAD program.

What’s your opinion about gEDA?

It would be really cool to create a “total GNU” solution for the
GNURADIO.
GNU EDA tools, GNU-like Hardware (open-source community license),
GNU FPGA-code, GNU

20

schrieb Marcus D. Leech on 2011-01-13 04:56:

On 01/12/2011 10:46 PM, Brian P. wrote:

 o USB-3.0
 o PCIe

o direct (embedded)
Any chance to transfer via eSATA? Quite common nowadays.

But maybe that’s the road to more expensive, not less (although cost
is only ONE of the factors
of a project like this).

First, price is one constraint, or one of the features, that would make
such a device attractive to a wide audience. Others would be
flexibility, simpleness, that is fitness for home building,
capabilities: lowest/highest frequency, dynamic range, simultaneous
bandwidth, DDC, filtering, FPGA; RX only vs.s RX and TX; interface and
others.

For price: I’d say 200$-300$ for a tunable frontend, 16bit resolution,

500kSps and flexibility to support IF input, clock input, digital
stream output (for other transport/consuming system) DIY-kit is
attractive. If the flexibility is not available, this would be to
expensive. Phillip Balister tried to connect a USRP to a Beagle Board,
which was not so easy because the USRP hat no way to tap the data
between the FPGA and the USB interface.

For flexibility, being able to bypass stages or feed signals e.g. at the
ADC would be cheap. Preparing for different transport systems would make
it more future proof. If USB3.0 hardware support is not satisfying now,
maybe it is in two years. For the data bus part this would require a
prepared interface for data and control lines.

I see the target for such at above all the soundcard solutions and below
the USRP1. USRP1 can do 8MHz Bandwidth complex at 14bit/sample RX, which
is more than enough for hobbyists. What would be interesting for
university teaching and research? What would be interesting for other
potential users, like hams? Did I miss some?

USB3.0 is common at new high end PCs and Laptops, ExressCard at Laptops.
Of course every PC with PCIe is ubgradable to both of them, but it’s
extra money to spend and extra hassle to get it started. I do not see
urgent need for such extreme data rates. This could be a second step.

For a start, a not too expensive, but still capable system with options
for extension seems most doable for me. If the transport systems is to
be fully integrated in the first shot, at least the data should be
accessible via some interface.

Patrick

Engineers motto: cheap, good, fast: choose any two
Patrick S.
Student of Telematik, Techn. University Graz, Austria