Nandblasting not working in one xo

[John Watlington]

NANDBlaster uses a fixed transmit speed (modulation).
If the signal budget for a laptop isn't sufficient to support
that speed, it will fail to receive many packets.

When using normal WiFi, the transmit speed (modulation)
is decreased until reliable communication can be obtained ---
therefore a laptop with decreased signal budget (e.g. bad antenna)
may still work, although with degraded performance.

Regards,
John

On Jul 9, 2012, at 11:10 PM, James Cameron wrote:

> That the antenna change did not work shows the problem is in the
> wireless card.
> 
> You asked why not use the same mechanism as Sugar?
> 
> Consider the transmitter performance.
> 
> Your network used by Sugar probably has an access point with higher
> transmit power and better antenna than the laptop being used as
> NANDblaster sender.
> 
> So it is perhaps the combination of small damage to one laptop and
> large damage to another laptop, that causes NANDblaster to fail.  But
> the combination of good access point and large damage causes Sugar
> networking to be successful.
> 
> See http://wiki.laptop.org/go/Antenna_testing#Link_Budget for a
> calculation of wireless success, to see what variables are important.
> 
> Does Sugar in ad-hoc wireless mode work between the two laptops?  Or
> Sugar in mesh wireless mode with no other laptops nearby?
> 
> If so, that's very interesting.
> 
> Open Firmware and Linux use different commands sent to the wireless card.
> 
> I've checked, and we are using the same wireless firmware 5.110.22.p23
> in both Open Firmware and Linux (build 883).
> 
> Daniel, do you know of any commands that the Linux kernel may have
> sent to the card that may improve signal, even by accident?
> 
> On Mon, Jul 09, 2012 at 04:06:16PM +0545, Roshan Karki wrote:
>> I tried with antenna change but as you told, didn't work. So I think this is
>> the dead end. Thank you for your help. But one question I wonder is in Sugar I
>> can use very poor network very well. Why not use the same mechanism in OFW as
>> well?
>> 
>> On Fri, Jul 6, 2012 at 10:41 AM, James Cameron <quozl at laptop.org> wrote:
>> 
>>    G'day,
>> 
>>    Thanks for the photographs.  There's nothing wrong that I can see
>>    either.
>> 
>>    Repair may attempt antenna change, but it is unlikely to be fixed with
>>    only antenna change.
>> 
>>    Perhaps the radio module has been damaged.  On XO-1 the module is
>>    soldered down and is impractical to replace.  In later models (XO-1.5,
>>    XO-1.75) the module is in a socket.
>> 
>>    --
>>    James Cameron
>>    http://quozl.linux.org.au/
>> 
>> 
> 
> -- 
> James Cameron
> http://quozl.linux.org.au/
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