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Comment: Maybe they should stop sleeping with the partners (Score 1) 365

by dbateman (#39025615) Attached to: Ontario Teachers' Union Calls For Health-Related Classroom Wi-Fi Ban

as well as they the human body radiates about 100Watts or 500 times more power than the maximum allowed power from a WiFi access point. Going out it sun is definitely out as at 1kW per square meter of 5000 times strong than WiFi that definitely going to be fatal...

What a load of Bollocks!

D.

Comment: Re:Funny, I heard the same thing about their camer (Score 1) 252

by dbateman (#36183332) Attached to: Computer Records Hold Key In IMF Head's Sexual Assault Case

You do of course realize that DSK was the man most likely to be the next president of France up until this accusation? French politics is not really that clean either. Lookup "clearstream sarkozy" and look at how another party infight turned to corrupt means to taint Sarkozy's image before the last election, which backfired and ended up even boasting his popularity, eliminated the other presidential candidates.

The next presidential election in France is in May 2012 and the socialist party is just about to select their candidate. The timing of this scandal is just "too" convenient. If he is guilty most French people I know say "let him hang", but most also have serious doubts given the political context surrounding the case.

D:

PS: Though I live in Paris, I'm not French

Comment: Re:Godzilla (Score 1) 1148

BRAZIL = Cheap labor + Lots of Sun + Low population density = Cheap biofeul

Sorry Brazil's model applies to very few countries in the world. Read the report "Without the hot air" (url http://www.withouthotair.com/) if you want to see how Brazil's model would fair went applied to the British situation, which is fairly a rather depressing read.

D.

Comment: Re:rock in water... (Score 1) 244

by dbateman (#35215432) Attached to: Two-way Radio Breakthrough To Double Wi-Fi Speeds

Except that from my days working with ADCs and coherent demodulation I know that 1deg of phase error between the two transmit signals will reduce the isolation between the two transmitted signal to 40dB. That 1deg of phase difference is 0.3mm at 2.4GHz

The authors say they need 50dB of isolation, whereas as my guess they need more like 60dB for a reasonable transmit power. There is a need to precisely place three antennas probably about 10cm apart with a positioning error of a very very small fraction of a mm. Difficult to do and mechanically fragile

Not to speak about the fact that the positioning is frequency dependent and so this is going to be an extremely narrowband radioband system.

D.

Comment: Re:Actual information (Score 1) 244

by dbateman (#35215256) Attached to: Two-way Radio Breakthrough To Double Wi-Fi Speeds

And have you seen that their first active component in the receive path is an intersil qhx220 that is a noise cancelling LNA. The IIP3 of this LNA is about -21dBm at 2.4GHz, so the P1dB will be about 10dB under that, and OFDM signals typically needing 5dB backoff from the P1Bb to get in the PER specs of 802.11x. So lets assume they are transmitting 15dBm from their transmit antennas (typical for a portable WiFi device) to avoid your LNA going non-linear you want to the cancellation of the transmit signals at the receive antenna to be more like 60dB of cancellation. Even if they get that in the antennas I hope their receive electronics are well shielded because even ignoring the antennas, getting the isolation between the transmit and receive paths better than 60dB is going to be a challenge in a low cost and/or small device. So this thing is going to be gold plated and hand tuned to even get it to partially work

D.

Comment: Stargate = Satimo SG64 (Score 1) 229

by dbateman (#32944970) Attached to: Inside Apple's Anechoic Testing Chambers

These things have been sold for over 10 years by the French company Satimo for the type of rapid antenna measurements that are needed when you're measuring in the presence of a human. Look at the website

http://www.satimo.com/content/products/sg-64

This is hardly a sign that Apple is modern, but rather they are following behind the antenna measurement industry,

D.

Comment: Re:Hmmm... (Score 1) 320

by dbateman (#30329878) Attached to: Cell Phones Don't Increase Chances of Brain Cancer

Except supratentorial gilomas being tumors that form outside the membrane of the brain are a type of tumor that is more likely to be in close proximity to the ear (rather than deeper in the brain) where the specific absorption of microwaves will be the highest.. Seems like a good type of brain tumor to base a study of the effects of mobile phones on the brain on.

D.

Comment: Re:Use only channel 1,6 and 11. (Score 1) 451

by dbateman (#26499879) Attached to: How Best To Deal With WiFi Interference?

Yes its standard practice, but no it doesn't produce the best strategy in the context of 802.11. The problem is that the 802.11 MAC clear channel assessment minimizes the opportunity for interference but in fact reduces the opportunity to transmit even in cases that won't interfere. That is I might be trying to communicate with an AP that is 10 metres away, but can see a transmission on the same channel from an AP 100 metres away and the CCA will prevent me from transmitting, even though I probably won't interfere with the other transmission and he certainly won't interfere with me.

The CCA in 802.11ag is defined in two different manners. The first is that if I can synchronize with a preamble in the channel then I consider the channel occupied. This basically means that anything I can hear at the receiver sensitivity (-85dBm for 802.11ag) in my channel I won't transmit. However this doesn't help for the issue of overlapping channels or non 802.11 transmissions in band. So the second definition is a simple RMS power measurement at 20dB above the receiver sensitivity level. That is if I hear something at -65dBm in my band I don't transmit regardless of what type of signal it is. So I'd rather have someone transmitting on the same channel as I am as far away as possible, and adding more, but overlapping channels, giving the frequency planner more opportunities to do that.

Therefore a better frequency plan in the 2.4GHz band that gains a 20dB advantage from the CCA definition is 1, 7, 13, 2, 8, 14, as that minimizes channel overlaps while maximizing the distance. However channel 14 isn't always available and so 1, 6, 12, 2, 7, 13 is a compromise that is reasonable.

Note that the 802.11n "green-fields" preambles have a better definition of the CCA that is basically the same whether or not your on the same channel. However, I don't think anyones really using these new preambles in 802.11n yet.

D.

Security

+ - Forensic computer targets digital crime->

Submitted by
coondoggie
coondoggie writes "A European consortium has come up with a high-speed digital forensic computer dedicated to the task of quickly offloading and analyzing all computer records from email or picture files to database contents and file transfers.The TreCorder is a rugged forensic PC able to copy or clone up to three hard disks simultaneously, at a speed of up to 2 Gb/min. The same transfer would take 30 to 60 minutes using alternative equipment. The PC not only provides a complete mirror image of the hard disk and system memory — including deleted and reformatted date — but also eliminates any possibility of falsification in the process, Hermann said. It uses the FireWire high-speed serial bus to connect the host computer and provides support for IDE, SATA and SCSI hard disks. http://www.networkworld.com/community/node/19197"
Link to Original Source
Security

+ - Stampedes can be predicted by CCTV software

Submitted by Anonymous Coward
An anonymous reader writes "Analysis of footage from the Jamarat Bridge stampede tragedy during the 2006 Hajj pilgrimage has shown up new processes that can be used to predict when such a disaster will occur. Sharp waves move through a crowd before a turbulent phase when people are jostled in unpredictable directions, when they are likely to fall, leading to a stampede. Software used by the researchers could be used to provide warning before this stage is reached."

What this country needs is a good five dollar plasma weapon.

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