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

John Watlington wad at laptop.org
Mon Jan 25 22:55:49 EST 2010


On Jan 26, 2010, at 4:58 AM, Luke Kenneth Casson Leighton wrote:

> On Mon, Jan 25, 2010 at 6:33 PM,  <david at lang.hm> wrote:
>>> the key questions to be asking are: in light of the massive volumes
>>> involved with OLPC XOs, is SDR worth pursuing, given all the
>>> development costs, but given all the benefits especially where  
>>> SDR can
>>> be re-programmed to do "whatever" in bands where licensing and
>>> regulatory approval is _not_ required, on a per-country basis?
>>
>> probably not, for the same reason that OLPC isn't writing it's own OS
>> anymore. it requires extensive expertise and tools that they don't  
>> have.
>>
>> they funded the developement and deployment of the screen  
>> technology, but
>> everything else has been assembling off-the-shelf chips and  
>> subsystems, and
>> with the changeing times, they have less engineering expertise  
>> than they
>> used to.
>
>  ok - i'm asking the wrong question :)
>
>  let's assume that somewhere in 2010 an SDR modem exists (from
> someone, doesn't matter who made it).  let's assume that software is
> available (COTS) and is (perhaps temporarily, perhaps permanently)
> proprietary and turns on the SDR for specific functions.  let's assume
> also that the specs on the SDR RF side are completely documented,
> publicly available and, importantly, useable by free software (for the
> future, for replacing the COTS firmware).  let's assume that the SDR
> modem and the COTS firmware which actually turns it into WIMAX, 3G,
> GSM, 802.11 etc. is available; let's assume that the SDR modem comes
> with instructions "just plug in this 802.11 antenna here; just plug in
> this Quad-band Penta-band GSM/3G antenna here; just plug in the GPS
> antenna here".
>
>  _if_ all these things were true, _would_ the OLPC hardware design
> team select such a COTS modem and its associated firmware
> (over-and-above the rather dull Marvell 88688 option being deployed
> right now in XO-1)?

The XO-1 uses the 88W8388, which I've never heard anyone describe
as "dull" before...   The XO-1.5 uses the 88W8686, which I hope is nice
and dull from an engineering point of view (it has been so far.)

> and if so, who do i need to talk to, to get a "yes" from?

speaking

> (and if not, what _would_ it take for an SDR modem to be selected?)
>  this last is perhaps the key question.  what's it going to take to
> get an SDR modem into a future XO?

Equivalent performance, for an equivalent cost and power budget.
Whether to use fixed hardware or software is a frequent engineering
decision.   At the prices you quoted, I can currently get multiple  
dedicated
hardware interfaces for the same price, and almost certainly for  
lower power.

The certification issues for SDR haven't been settled, either.
I don't know of any products w. SDR shipping with user modifiable
software at this time.   Can you point me to some ?

Cheers,
wad




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