OLPC hardware: what if there was an SDR modem / chipset?

John Watlington wad at laptop.org
Tue Jan 26 08:29:29 EST 2010

On Jan 26, 2010, at 6:46 PM, Luke Kenneth Casson Leighton wrote:

> (and i also specifically mentioned the gnu-radio project resources as
> being one option.  there are a _lot_ of people who would be
> _extremely_ happy to not have to spend $750 on a USRP in order to do
> free software development gnu-radio.)

That's nice, but OLPC does not exist to provide development
platforms for hackers.  We exist to provide high quality laptops
at cost to kids in the developing world.

>> Re certifications, on both XO-1 and XO-1.5 we
>> use slightly non-standard modules (on XO-1 to
>> support 802.11s, on XO-1.5 to reduce power
>> consumption by 50%) and have paid the full
>> certification costs.   They run about 100K$ for
>> starters, with each additional country adding
>> around 5K$.
>  ok.   interesting to know.  ridiculously high, but important to know.
>  and, given that they _are_ non-standard, such that the full
> certification costs would have to be paid, that means that you're "in
> the game" already for paying such up-front certification costs if
> there was a ready-made off-the-shelf SDR modem kicking around.

High, but not ridiculously, given the cost of the equipment and staff
required for certification.    However, you are missing a crucial point
about SDR.

See http://lwn.net/Articles/240840/
in particular, the comment at http://lwn.net/Articles/240921/

(pulling in Luke's comments from a previous email:)
>  ... did you have to sign an NDA in order to get the firmware, and can
> the 88W8686 be reprogrammed by anyone?  if i want to write my own
> peer-to-peer 802.11 algorithms, doing an implementation e.g. of the
> Babel routing algorithm to run actually on the WIFI chip itself, can i
> do so, right now, _without_ being forced to sign a Marvell NDA?

As the previous links point out, getting certified for sale and meeting
your desires are mutually exclusive at the current time.

>  * what's the current price;
>  * what's the current power budget (given that 802.11 is 100mW max or
> 400mW max in Hong Kong)

I can't release the current price, but it is lower than $9.
The current 8686 SD WLAN module pulls about 400 mW
(peak, total on all supplies) when operating.   The power numbers
you are quoting are RF output power --- I am talking about
how much power must be supplied to the module for operation.

> *  the USRP from ettus research ($750 and made of discrete components)
> *  the lyrtech SDR developer kit (again, discrete components)

These are not consumer products certified for sale, they are
development boards.   If I can't certify it for sale in every
country in the world, I can't use it in an XO.   Read the above links,
and remember that the FCC is liberal compared to the EU regulators.


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