* Posts by Hotears

18 posts • joined 4 May 2010

Dell won't ship energy-hungry PCs to California and five other US states due to power regulations


"10-17 J/bit" .. either no proofreading or the author has no sense of a joule. Let's convert some of the numbers mentioned to SI:

50kWh/year = 5.7W

100kWh/year = 11.4W

And here I was proud that I'd gotten the fibre cpe, switches, server, APs, and house heating controller down to 54W total.

Boffins improve on tech that extracts DC power from ambient Wi-Fi


We can put a quick upper bound on this, as it is being sold to the press. Everyone here probably have wifi analyzer or something similar on their phone:

Right now, I have -55dBm from my closest (8m) access point, and -70 dBm from next closest. -70dBm is 30x weaker in linear power than -55dBm, so we can ignore that, and the neigbours.

0dBm is one milliwatt coming from the antenna in the phone. -30dBm is one microwatt. -50dBm is 10 nanowatt. -55 is 3 nanowatt.

As a sanity check we can take 100mW EIRP and divide by the area of the sphere, we get an upper bound of 12nW/cm2 with no walls.

Ahem. And that assumes 100% tx duty cycle on the access point. Reality is 5%.

for the led demo, they'd need in the order of 100uW after losses, 200uW into the antenna, for a 10x10cm antenna we need 20mW/m^2, we are 0.7m from a continuous 100mW transmitter.

(I am not going to try to convert to sheep in vacuum * norris )

The silence of the racks is deafening, production gear has gone dark – so which wire do we cut?


Silence of the fans

Oddly enough, the times my mistyping or forgetfulness has brought down kit, either the customers were quite happy to be told before they noticed, or the resulting loss of smoke was not expensive enough to worry about. Green fire yes, but nothing worse than that.

There was the night I arrived at work expecting to find that the flaky router we were trying to figure out had fallen over again, and tried to get on wireless. No luck. Very odd. New plan, prop open the door to the switch room and plug directly into the core - only the links to the server room in question were all dark.

The sensation of walking through what should have been an operating server room, alone and at night, with the bit of sand you have under your shoes crackling loudly, was kind of neat - though it took four hours I would rather have spent in bed to get the Aperiodic Pixie Converter with its failed bypass relays bypassed.

Galileo, Galileo, Galileo, where to go? Navigation satellite signals flip from degraded to full TITSUP* over span of four days


Let's start a ficitcious betting pool. And since I get to go first, I pick 'Windows+CryptoLocker'.

How do you solve a problem like Galileo? With a strap-on L-band payload, of course!


Re: Hirzon angles??

With GPS, they knew from the start that four satellites in view would be required, three if the receiver had a good atomic clock. The system preceding Navstar-GPS was Transit; That one, with three satellites, was fine to provide daily position updates to your handy battleship or nuclear sub. The rest could be - and still can be - handled with inertial navigation.

I did get a navigation fix back when only four Galileo sats were usable. I also just managed to build a receiver and get a fix before Loran was crippled. There are a few ways to build a navigation system, but if it isn't really expensive, it's not politically hot, so forget about those solutions.

Europe is living in the past (by nearly six minutes) thanks to Serbia and Kosovo


Re: Still getting worse?

And another second. And a half.


I began monitoring the power line awfully early sunday morning; It looked reasonably under control for the first 24 hours, now it is entertaining again. If you are the type who enjoys waching phase drift.

This is plotted every 20 minutes, so jumping on the refresh button more often than that won't help.

Gigantic data file available on request.

How to remote hijack computers using Intel's insecure chips: Just use an empty login string


Am I the only one with a small heap of intel desktop boards?

"Intel no longer provides email, chat or phone support for this product."

Someone just chucked another $21 million at carbon nanotube memory techies


Re: 50ns

Actually, 50ns is not bad compared to DRAM. It is true that latency is much better than that once a row is opened, but when you then want to access a different row you have to close the row, precharge the sense amplifiers, open the new row, and only then can you read quickly (or rather the memory controller in the SoC you are using does this for you, but it still takes time).

If constructed in a similar way (wide rows), NRAM will, if the access time is ~50ns, be about the same.

The first market I expect it to appear in is small nonvolatile memories for industrial purposes. I currently use 32kByte MRAM and FRAM parts, and I pay around USD3 each for them in quantity.

Inside Android's source code... // TODO – Finish file encryption later


Not the only encryption TODO in 7.0

This is not the only mess-up. They also managed to lose SECP384r1 support from the TLS stack used by the apps. Firefox and Chrome have their own stacks, they are not affected. But the mail client is a biggie, in 7.0 it can no longer talk to imap and smtp servers using nicely strong ecc crypto. This leaves me with the option of either turning down encryption for all users (yeah, right), maintaining duplicate service just for android 7.0 clients (expensive), or deciding not to support android 7.0 clients.


Microsoft blames dying Surface Pro 3 batteries on software bug


30GWh in 5 months lets us do some calculations. 5 months is 3600 hours, so the average power is 8.3 MW. The surface area of both sides summed is approx. 0.12 m^2, so temperature rise with the device vertical in still air with convection currents will be ~0.5K/W. So this thing will idle at ~4.7 megaKelvin. Display brightness will not be a problem.

IT bods: Windows XP, we WON'T leave you. Migrate? Chuh! As if...


Embedded? Not so simple.

On the production floor I have a few million pounds, dollars, or euros worth of machinery, with some of the embedded machines running XP. It has custom hardware and drivers. Basically, components go in on one end, earnings comes out the other. Am I going to turn it off?

Not likely. At this point it's on its own network, with tight access controls. That's all I can do.

How heavy is your remaining XP box? Mine's about 20 tonnes.

Wireless breakthrough: one frequency, multiple signals


While I wouldn't mind seeing Shannon's communications theory or the second law of thermodynamics disproven, I do not have high hopes for this.

Raspberry Pi signs big-name sellers


"Yay?" In Denmark, both Farnell and RS-Components are strictly B2B. So even if I want one to play with, they won't sell it to me.

Chinese confirm Beidou satnav system is operational


No L5 equivalent?

This is pretty much GPS L1 (not surprising, DSSS is a good way to do it), at a slight frequency offset, at twice the chip rate (better code tracking precision, position/timing wise).

What surprises me is that there is no L2/L5 (in GPS terms) equivalent signal. Your everyday L1 receiver depends on a ionosphere model to compensate for the delay through the atmosphere. In GPS, L2 allows the delay to be measured, resulting in great precision enhancement. The reason your everyday receiver doesn't do L2 is it is military-only and encrypted. Thus, the latest GPS sats have L5, which is the same thing, just not encrypted.

I'm confused.

NASA tells Voyager 2 to save its strength


There isn't enough sunlight out there, our sun looks like a star. So it uses radiothermal generators. The fuel is plutonium, and as it decays, over the years, the power output drops. So now they have nowhere the power they started with.

The biggest risk with RTGs seem to be people stealing the outer casings for scrap value, luckily the Voyagers have adequate theft protection.

World IPv6 Day fails to kill the internet


already there.

As someone sitting on an already-enabled network, it was an interesting day.

The phone did not ring. And I had even told people to report problems.

IPv6 traffic was pretty high. At least 10x usual. Mostly because of google and youtube.

My ntp server, being the ONLY IPv6 server in the ntp pool for the given zone, got a bit of traffic.

which was fun to watch.

The server-end providers got it right. No surprise, it really is pretty simple.

If you are a IPv4-only user, get IPv6. Because it is not a question of me 'just being cross'. Very simply, I do not have any more IPv4 addresses. My upstream will not give me any more addresses. If you want to use my newer services, you will have to use IPv6.

IP registry goes to Defcon 1 as IPv4 doomsday nears


Not much pain

3 years ago I started a slow 'when convenient' slide towards IPv6. Today I am sitting on a fully working and tested dual stack network. But if you have been completely ignoring it, yes, you will be staying up. So why have you been ignoring it?

dig AAAA www.theregister.co.uk returns no records, so go get some Provigil.

@cowards: Even if you could find and reclaim the (fragmented) unused IPv4 space, it would be like peeing in your pants, so for one I welcome the first RIR pool depletions. It turns 'expected to happen' into current reality, which is much easier for management to relate to. And we're still running stateful firewalling on IPv6. Just like on v4. NAT makes zero difference. Zero state tracking does.

Pirate Bay dishes up Iron Man 2 ahead of US release


And it is not necessarily a downside box office wise

More than half the times I visit the big screen, it is because a someone I know - and know the tastes of - says that this is a movie I will like, and we should make an event out of it. Friends, beer (good stuff), and good sound. Funny thing is, the planning takes longer than the attention span of cinemas here.

With digital projectors now in place, I must assume they try to find the balance between disinterest and hype.


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