Re: [Discuss-gnuradio] OLPC - next generation with SDR?

[Brian Padalino]

On Dec 25, 2007 6:05 PM, David Hartzell <[EMAIL PROTECTED]> wrote:
> DRM is pretty cool and has the /potential/ to provide the kids with a
> multimedia experience, even if it takes two laptops "chained" together
> to decode the signals...

If the linking were in fact required, it would at least introduce the
concept of distributed computing at a young age and, possibly, with a
new and different perspective of how to accomplish some of the harder
tasks.

Since there is a pretty serious size, weight and power (SWAP)
restriction when dealing with something like the OLPC, complete
integration is key.  I've been eyeing a Maxim Analog Front End (AFE)
that is dual channel, 10-bits and is extremely low power and cost.

http://www.maxim-ic.com/quick_view2.cfm/qv_pk/5163

Although [EMAIL PROTECTED] is a little steep, it's also the cheapest and most
fully featured low-power AFE I've really seen and at 7mm x 7mm, it's
almost trivial for real estate.

Given this core technology, and Matt's experience in IC design coupled
with the quantities an OLPC will be shipping in, it might be possible
to negotiate with Maxim to throw the current CIC filters +
programmable decimating FIR filter along with this core on some
silicon for not much or any more money - basically a hardened
low-power USRP that can hang off the ARM in a memory mapped area.

The potential is there for sure.

Brian


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Re: [Discuss-gnuradio] OLPC - next generation with SDR?

[David Hartzell]

John Gilmore wrote:
What kind of antenna would this require? Something external to the 
laptop? Or something that could be built into the plastic case?
Gotta go with an external antenna, hopefully something like an RCA 
plug.  If we're trying to encourage kids in developing nations to get 
into technology, this would be it.  That's how I got started twenty 
years ago, with a long-wire connected to an RCA plug, which isn't too 
much real-estate on the case. 

DRM is pretty cool and has the /potential/ to provide the kids with a 
multimedia experience, even if it takes two laptops "chained" together 
to decode the signals...


Dave





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Re: [Discuss-gnuradio] OLPC - next generation with SDR?

[Robert McGwier]

Frank Brickle wrote:
> On Dec 24, 2007 5:11 PM, John Gilmore <[EMAIL PROTECTED]
> > wrote:
> 
> The Odyssey board operates at 10MHz IF; so wouldn't it need an external
> tuner?
> 
> 
> Yes, but many different tuners (band sets) can be serviced by the same
> IF processor.

Not to mention that Odyssey can take a few dollar DDS input in place of
the crystal and tune all of the HF shortwave bands.  The performance
will go DOWN because of the spurs generated by the inexpensive DDS but
that is probably acceptable as opposed to people not having a shortwave
radio at all or only those they cannot afford.   Further, to increase
performance, some kind of band switching apparatus, strictly for front
end filtering changes, needs to be provided.



>  
> 
> What kind of antenna would this require?  Something external to the
> laptop?  Or something that could be built into the plastic case?
> 
> 
> Depending on the band it could be either or both. A multiloop MW/HF
> could be embedded in the plastic case. A gender-bent SMA could
> accommodate a wide variety of V/U/SHF antennas.
>  
> 
> 
> We won't need a processor; the laptop will come with a processor much
> faster than 40 MIPS.  (The current XO CPU is a Geode LX 433 MHz x86,
> with MMX, 3DNow, and some SSE instructions.)

The OLPC chip is capable and can run a small dedicated sdr/dsp core to
do many functions.  I would like to see us offload stuff on to some kind
of helping processor so we could do more than just 5 kHz wide AM/SSB, or
NBFM, etc.
> 
> 
> We can argue that a "radio coprocessor" would greatly enhance the range
> of possibilities -- DRM (Digital Radio Mondiale) for example, and see
> below.
>  
> 
> > We need a DDS and a QSD (we do not need the QSE for the receive only
> > version) if we are going to tune the HF shortwave broadcast bands and
> > get reasonable performance at low cost.
> 
> I think that single chips are available that do broadcast-band AM and
> FM decoding for cheap; has nobody done this for the television and
> shortwave bands?  Or is the problem that nobody's done this digitally?
> 
> 
> Two problems. One is that the off-the-shelf chips use proprietary IP.
> The other is that the off-the-shelf chips are locked up and it's next to
> impossible to do anything interesting with them that you can't already
> do with a cheap external radio. I'm not aware of commercial devices that
> could be used to capture and detect *all* of the signals within a 50 kHz
> bandwidth, which could probably be done with ease with the assistance of
> a radio coprocessor. This is an essential step towards "cognitive"
> functions -- make the radio functions mutable and dynamic.
>  
> 
> If we can provide something that gives real benefit for the target
> kids, we shouldn't be dogmatic about analog versus digital.
> Alternatively, if OLPC provided a million-unit order for a digital
> tuner chip that would target all these bands, others could then buy the
> cheap chip for a variety of projects.
> 
> > This would provide a clear example of how it could be done.  It
> does not
> > meet the price point, but it shows the capabilities and then we can
> > negotiate.
> 
> I'm glad you-all are pointing out low volume prototypes... 
> 
> 
> I'd think in part we'd be providing not just sealed up applications but
> also programmable devices and an API, capable of being used in
> innovative ways in software *without* requiring the chronic intervention
> of large-scale chip producers. Part of the SDR mission, isn't it?

Open Standards, open source, free infrastructure?  That is a little
radical isn't it?  Should that be our mission?

I certainly hope so.  That is my life's mission, which I am grateful in
the extreme that my employer is allowing me to pursue with a vengeance
and with (probably) more clout than I deserve. I am determined to help
end the repeated purchase of, and closed system support of,
infrastructure that should be available to all (and which we are tired
of paying for over and over and over).  With this freeing of resources,
we would be leaving the companies, individuals, governments, students,
WHATEVER, to innovate ON TOP of that already done infrastructure.  Think
of how much more productive the existing money pool would be if almost
ALL infrastructure code was free (operating systems, word processors,
spreadsheet, radio basic functions, etc.)  and we were not having
companies, governments, etc. repeatedly paying for the same closed
system infrastructure to be done as well as the huge support tail for
maintaining it. Then companies would be free to spend lots more of their
money on innovation, creativity, and more, held back then mostly by the
huge part that must go to lawyers to make sure they have a sufficiently
large patent portfolio to defend the innovation (Can we stop that next?)
 I just don't understand why all of the corporate, governme

Re: [Discuss-gnuradio] OLPC - next generation with SDR?

[Frank Brickle]

On Dec 24, 2007 5:11 PM, John Gilmore <[EMAIL PROTECTED]> wrote:

The Odyssey board operates at 10MHz IF; so wouldn't it need an external
> tuner?


Yes, but many different tuners (band sets) can be serviced by the same IF
processor.


> What kind of antenna would this require?  Something external to the
> laptop?  Or something that could be built into the plastic case?


Depending on the band it could be either or both. A multiloop MW/HF could be
embedded in the plastic case. A gender-bent SMA could accommodate a wide
variety of V/U/SHF antennas.


>
> We won't need a processor; the laptop will come with a processor much
> faster than 40 MIPS.  (The current XO CPU is a Geode LX 433 MHz x86,
> with MMX, 3DNow, and some SSE instructions.)


We can argue that a "radio coprocessor" would greatly enhance the range of
possibilities -- DRM (Digital Radio Mondiale) for example, and see below.


> > We need a DDS and a QSD (we do not need the QSE for the receive only
> > version) if we are going to tune the HF shortwave broadcast bands and
> > get reasonable performance at low cost.
>
> I think that single chips are available that do broadcast-band AM and
> FM decoding for cheap; has nobody done this for the television and
> shortwave bands?  Or is the problem that nobody's done this digitally?


Two problems. One is that the off-the-shelf chips use proprietary IP. The
other is that the off-the-shelf chips are locked up and it's next to
impossible to do anything interesting with them that you can't already do
with a cheap external radio. I'm not aware of commercial devices that could
be used to capture and detect *all* of the signals within a 50 kHz
bandwidth, which could probably be done with ease with the assistance of a
radio coprocessor. This is an essential step towards "cognitive" functions
-- make the radio functions mutable and dynamic.


> If we can provide something that gives real benefit for the target
> kids, we shouldn't be dogmatic about analog versus digital.
> Alternatively, if OLPC provided a million-unit order for a digital
> tuner chip that would target all these bands, others could then buy the
> cheap chip for a variety of projects.
>
> > This would provide a clear example of how it could be done.  It does not
> > meet the price point, but it shows the capabilities and then we can
> > negotiate.
>
> I'm glad you-all are pointing out low volume prototypes...


I'd think in part we'd be providing not just sealed up applications but also
programmable devices and an API, capable of being used in innovative ways in
software *without* requiring the chronic intervention of large-scale chip
producers. Part of the SDR mission, isn't it?

Regards
Frank
AB2KT
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Re: [Discuss-gnuradio] OLPC - next generation with SDR?

[David Young]

On Mon, Dec 24, 2007 at 02:11:34PM -0800, John Gilmore wrote:
> I'm glad you-all are pointing out low volume prototypes.  I hope we'll
> get someone interested who has designed high volume digital radio
> electronics.  High volume ~= million-unit.  (Do any people like this
> exist?  Perhaps Matt's bluetooth design has shipped in that quantity;
> WiFi does too.)  There's already an entire high speed digital radio
> transceiver in the existing XO: it's the Marvell "Libertas" WiFi
> 88W8388 controller chip and 88W8015 radio chip.  It's reprogrammable,
> though the ARM code that runs in it isn't open source yet (the high
> level code can be open sourced, but it runs on a proprietary RTOS).

You may be disappointed what you can accomplish with the ARM
microcontroller.  It is not responsible for mod/demod.  Those functions
are in silicon.

If Marvell would publish the 88W8388 and 88W8015 documentation, it
would jumpstart some open-source development.  Source code is a poor
replacement for proper chipset documentation.

Dave

-- 
David Young OJC Technologies
[EMAIL PROTECTED]  Urbana, IL * (217) 278-3933 ext 24


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Re: [Discuss-gnuradio] OLPC - next generation with SDR?

[John Gilmore]

As preface, I'm not a radio engineer.  I'm a software guy with
pretentions to understanding digital hardware.  I have a few signal
processing books on a dusty shelf.  You lose me as soon as you start
talking "Q signals".

The Odyssey board operates at 10MHz IF; so wouldn't it need an external
tuner?

> I am in agreement with Frank that we can currently do it for a few tens
> of dollars ~$50 in small quantities and that include parts and boards.
> We can even put together a prototype which will allow HF shortwave
> reception from low bands through about 21 Mhz covering these bands:
> [15m thru 120m]

What kind of antenna would this require?  Something external to the
laptop?  Or something that could be built into the plastic case?

> The dsPIC33 has more than enough horsepower to provide good
> (synchronous) detected AM and even some modest AGC.

We won't need a processor; the laptop will come with a processor much
faster than 40 MIPS.  (The current XO CPU is a Geode LX 433 MHz x86,
with MMX, 3DNow, and some SSE instructions.)

> We need a DDS and a QSD (we do not need the QSE for the receive only
> version) if we are going to tune the HF shortwave broadcast bands and
> get reasonable performance at low cost.

I think that single chips are available that do broadcast-band AM and
FM decoding for cheap; has nobody done this for the television and
shortwave bands?  Or is the problem that nobody's done this digitally?

If we can provide something that gives real benefit for the target
kids, we shouldn't be dogmatic about analog versus digital.
Alternatively, if OLPC provided a million-unit order for a digital
tuner chip that would target all these bands, others could then buy the
cheap chip for a variety of projects.

> This would provide a clear example of how it could be done.  It does not
> meet the price point, but it shows the capabilities and then we can
> negotiate.

I'm glad you-all are pointing out low volume prototypes.  I hope we'll
get someone interested who has designed high volume digital radio
electronics.  High volume ~= million-unit.  (Do any people like this
exist?  Perhaps Matt's bluetooth design has shipped in that quantity;
WiFi does too.)  There's already an entire high speed digital radio
transceiver in the existing XO: it's the Marvell "Libertas" WiFi
88W8388 controller chip and 88W8015 radio chip.  It's reprogrammable,
though the ARM code that runs in it isn't open source yet (the high
level code can be open sourced, but it runs on a proprietary RTOS).

I think the best strategy for a $50 laptop's radio would be to have
either an internal antenna or a single connector; a small number of
cheap analog components; perhaps *one* analog/digital chip (multi
channel DAC/ADC "radio chip"); and stuff *everything* else into a
corner of the digital system-on-chip that implements the rest of the
laptop.  It's hard to prototype such a thing, though perhaps using an
FPGA that come with a fast embedded MIPS or ARM CPU would be the
closest.

The current XO uses two custom chips (the DCON display controller, and
the CAFE camera/flash/SD controller), some very custom "mesh" firmware
for the ARM core inside the WiFi chip, and some very custom firmware
for the EC embedded controller battery charger chip.  A $50 laptop
version would probably mash all these chips together with the CPU,
GPU, and its "southbridge" support chip, leaving only one
system-on-chip, plus flash, DRAM, a few external analog chips, and a
pile of analog electronics for power supply and such.

John



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Re: [Discuss-gnuradio] OLPC - next generation with SDR?

[Robert McGwier]

John Gilmore wrote:
>> The thing does appear to have sufficient horsepower to do some DSP.
>> I would like to think we can make several things available to this
>> project.  For example, I think a tunable HF receiver for shortwave AM
>> broadcast is easiy achievable for very modest cost. Further out, I
>> would to see the use of this machine and OFDM skywave to provide WAN
>> capability to large areas of the world without such capability.
> 
> If we were given a square inch of circuit board space, twenty cents
> for components and wires and connectors, four pins, 0.2 watts of power
> when operating, and half a million gates colocated with the CPU and
> memory bus, what radio capabilities could we offer to the next
> generation OLPC project?
> 
> That's the fun challenge.  Here's some background.
> 


I am in agreement with Frank that we can currently do it for a few tens
of dollars ~$50 in small quantities and that include parts and boards.
We can even put together a prototype which will allow HF shortwave
reception from low bands through about 21 Mhz covering these bands:

# 15 meters – 18.90–19.02 MHz – Seldom used.
# 16 meters – 17.48–17.90 MHz – Day reception good, night reception
varies seasonally, with summer being the best.
# 19 meters –15.00–15.825 MHz – Day reception good, night reception
variable, best during summer. Time stations such as WWV are clustered
around 15 MHz.
# 22 meters – 13.57–13.87 MHz – Similar to 19 meters; best in summer.
# 25 meters – 11.50–12.16 MHz – Generally best during summer; said to be
ideal during the period before and after sunset.
# 31 meters – 9250–9995 kHz – Good year-round night band; seasonal
during the day, with best reception in winter. Time stations are
clustered around 10 MHz.
# 41 meters – 7100–7600 kHz – Reception varies by region – reasonably
good night reception, but few transmitters in this band are targeted to
North America.
# 49 meters – 5800–6300 kHz – Good year-round night band; daytime
reception is lacking.
# 60 meters – 4400–5100 kHz – Mostly used locally in tropical regions,
though usable at night. Time stations are clustered around 5000 kHz.
# 75 meters – 3900–4050 kHz – Mostly used in Eastern Hemisphere, not
widely received in the Americas.
# 90 meters – 3200–3400 kHz – Mostly used locally in tropical regions,
with limited long-distance reception at night.
# 120 meters – 2300–2495 kHz – Mostly used locally in tropical regions,
with time stations clustered around 2500 kHz. Not technically a
shortwave band; resides in the upper reaches of the medium wave band

The dsPIC33 has more than enough horsepower to provide good
(synchronous) detected AM and even some modest AGC.

We need a DDS and a QSD (we do not need the QSE for the receive only
version) if we are going to tune the HF shortwave broadcast bands and
get reasonable performance at low cost.

This would provide a clear example of how it could be done.  It does not
meet the price point, but it shows the capabilities and then we can
negotiate.

Bob

-- 
AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL,
TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair
“An optimist may see a light where there is none, but why
must the pessimist always run to blow it out?” Descartes


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Re: [Discuss-gnuradio] OLPC - next generation with SDR?

[Marcus Leech]

John Gilmore wrote:
>
> My first thought is to just increase the sample rate and effective
> bits per sample of the audio processing hardware, and increase the
> number of channels so that ordinary stereo audio can happen
> simultaneously with analog I/O.  I think it's a crime that cheap
> analog I/O chips top out at 200 kilosamples per second.
>   
I think that adding a fast, complex, sampler capable of doing many
megasamples, with
  DMA support, etc, would be a worthy goal.   A little anti-alias
filtering and some
  digitally-controllable gain (70dB or more) in front of the samplers,
and you have
  yourself a nice little HF receiver.   I wonder if you could suck the
entire 30Mhz
  of HF spectrum into the Geode in one gulp if there's adequate DMA
support, etc?

If not, you'd probably like some hardware-based DDCs and decimators, etc.





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Re: [Discuss-gnuradio] OLPC - next generation with SDR?

[Frank Brickle]

John --

Have you looked at all at the Siren board? It's  part of the HPSDR and
Suitsat II projects: a low-power, low-cost SDR engine using the dsPIC33F
embedded controller from Microchip. The current design uses 10 MHz RF in and
out, and the QSD and QSE for complex sampling and excitation. There is also
an onboard TI stereo codec for I/O in the audio range. Digital data can be
synchronously imported and exported over one or more SPI buses.

It's not perfectly general. Many of the algorithms we'd like to run on it
need to be tailored to the hardware in a way that's more constrained than
we'd like in general. That notwithstanding, it should be capable of handling
48 kHz bandwidth, and muxing and demuxing several channels within that span.

So far, as far as I know, only prototypes and first-gen boards are in
circulation. The power consumption is already very low; there's a lot of
board real estate eligible for shrinking as well.

Frank

On Dec 21, 2007 11:02 PM, John Gilmore <[EMAIL PROTECTED]> wrote:

> > The thing does appear to have sufficient horsepower to do some DSP.
> > ...
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Re: [Discuss-gnuradio] OLPC - next generation with SDR?

[John Gilmore]

> The thing does appear to have sufficient horsepower to do some DSP.
> I would like to think we can make several things available to this
> project.  For example, I think a tunable HF receiver for shortwave AM
> broadcast is easiy achievable for very modest cost. Further out, I
> would to see the use of this machine and OFDM skywave to provide WAN
> capability to large areas of the world without such capability.

If we were given a square inch of circuit board space, twenty cents
for components and wires and connectors, four pins, 0.2 watts of power
when operating, and half a million gates colocated with the CPU and
memory bus, what radio capabilities could we offer to the next
generation OLPC project?

That's the fun challenge.  Here's some background.

The reason software radio hardware has always cost so much is that it
ships in low volumes.  The oscilloscope boards we started with were
$1400.  The USRP is many hundreds, and the USRP-2 will be more.  But
if the USRP's RF I/O capability was integrated onto a high volume
motherboard, it would cost a lot less -- maybe $50 or $25.  If it was
integrated into a chipset, even cheaper.  Similar but specialized
wireless capabilities are in USB wifi dongles that *retail* for $40.

Today's children's XO laptop is just the first in a series of high
volume, low cost laptops -- from a variety of vendors.  We can assume
that with each generation they will get faster, lower power, and
cheaper -- as we learn more about how to design and build in that
problem space.  (Until Dec 31, you can buy one for $400 -- and a
second one will go free to a kid in a developing country.  After that,
they won't be sold at retail.  See http://laptopgiving.org.)

For the next generation effort, if they have the design time, they are
likely to build a big custom chip that integrates a whole CPU, and a
pile of system and peripheral circuitry.  Their stretch goal is a
$50/ea laptop for kids, one that's much better than the current $200
one.

We know they will want 2-channel sound in and out.  They have
already jiggered their current hardware so that the audio biases and
filters can be switched out of the circuit, so that ordinary low
voltage sources and sensors can be plugged into the audio port and
used to sample real-world sensors.  They have full control of the
drivers, since they're basing the whole thing on Linux, and they have
real kernel hackers and real GUI hackers and such.  Their system
already uses wireless WiFi, so it has antennas, and they've done a
detailed radio analysis of the package and design.

The difference between this design effort and the other things the GNU
Radio crew has done is that the result has to cost only incremental
pennies, cost zero power when not running, and run on batteries when
running.  On the other hand, gates and connectors and small antennas
come almost free (they're making hard-tooled plastic molds anyway;
adding a connector or other wires is simple).  Assuming their basic
design provided roughly their current sound and analog input
capabilities, what could we recommend that they do in order to make
the platform much more capable for SDR?

My first thought is to just increase the sample rate and effective
bits per sample of the audio processing hardware, and increase the
number of channels so that ordinary stereo audio can happen
simultaneously with analog I/O.  I think it's a crime that cheap
analog I/O chips top out at 200 kilosamples per second.

Even making it able to receive AM-band and below, by plugging in a
wire of appropriate length as antenna, would provide years of
experimentation in the schools.  Should the analog circuitry be
wired up to the existing "cat ear" antennas on the laptop (which
are currently only used by the WiFi chip)?

The analog circuitry would need to be switchable for use in three
domains:  audio (speaker/mic), DC analog (sensors), and radio analog (SDR).

Could we make it usefully transmit?  Many of Matt's transceiver
daughterboard designs are very similar -- with only a few components
changed to set the frequency range.  If made in high volumes on an
existing board, what would the cost come down to?  Could we shrink a
single band transceiver into the above constraint?  Could we design a
cheap multi-band transceiver that lets these components be switched
under software control?  Can the CPU and the free signal processing
gates automatically measure and compensate for cheap
(signal-distorting) analog circuitry?

What kind of signal processing math hardware should we add to the
custom chip, assuming that the CPU itself would be low power/low
heat/low performance for its time?  Should this be a CPU math
accelerator, or should it be wired to the digitization hardware?
Should it do one thing well (if so, what?) or be more general like
traditional x86/PPC/etc DSP instruction sets?

Should we suggest making some of "our" gates of the custom chip into a
field programmable gate array, reconfigurable in software?  If so,
what