Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!

 



Forgot your password?
typodupeerror
×
Image

New Speed Cameras Catch You From Space 351

A new kind of speed camera that uses satellites to measure average speed over long distances is being tested in Britain. The "Speedspike" system combines plate reading technology with a global positioning satellite receiver to calculate average speed between any two points in the area being monitored. From the article: "Details of the trials are contained in a House of Commons report. The company said in its evidence that the cameras enabled 'number plate capture in all weather conditions, 24 hours a day.' It also referred to the system's 'low cost' and ease of installation." I can't wait to see the episode of MythBusters where they try to avoid getting a speeding ticket from a satellite.
Input Devices

Is the Line-in Jack On the Verge of Extinction? 411

SlashD0tter writes "Many older sound cards were shipped with line-out, microphone-in, and a line-in jacks. For years I've used such a line-in jack on an old Windows 2000 dinosaur desktop that I bought in 2000 (600 Mhz PIII) to capture the stereo audio signal from an old Technics receiver. I've used this arrangement to recover the audio from a slew of old vinyl LPs and even a few cassettes using some simple audio manipulating software from a small shop in Australia. I've noticed only recently, unfortunately, that all of the four laptops I've bought since then have omitted a line-in jack, forcing me to continue keeping this old desktop on life support. I've looked around for USB sound cards that include a line-in jack, but I haven't been too impressed by the selection. Is the line-in jack doomed to extinction, possibly due to lobbying from vested interests, or are there better thinking-outside-the-box alternatives available?"
Australia

Anti-Gamer South Australian Attorney General Quits 104

dogbolter writes "South Australian Attorney General, Michael Atkinson, infamous for the banning of R18+ rated games and the censoring of political comment in Australia, has quit. The recent South Australian election provided a massive swing against Atkinson's governing labor party. As a direct result of the South Australian election result, he is standing down. Hopefully someone with half a clue will assume the vacant post and overturn the decision to ban adult oriented computer games."
Earth

Piezo Crystals Harness Sound To Generate Hydrogen 187

MikeChino writes "Scientists at the University of Wisconsin-Madison have discovered that a mix of zinc oxide crystals, water, and noise pollution can efficiently produce hydrogen without the need for a dirty catalyst like oil. To generate the clean hydrogen, researchers produced a new type of zinc oxide crystals that absorb vibrations when placed in water. The vibrations cause the crystals to develop areas with strong positive and negative charges — a reaction that rips the surrounding water molecules and releases hydrogen and oxygen. The mechanism, dubbed the piezoelectrochemical effect, converts 18% of energy from vibrations into hydrogen gas (compared to 10% from conventional piezoelectric materials), and since any vibration can produce the effect, the system could one day be used to generate power from anything that produces noise — cars whizzing by on the highway, crashing waves in the ocean, or planes landing at an airport."
Space

Fastest (and Most Compact) Stellar Spinner Confirmed 47

gregg writes "HM Cancri has been confirmed as a binary system of two white dwarfs orbiting each other so closely that they complete one orbit every 5.4 minutes; they are separated by a mere 8 Earth diameters. 'These are the burnt-out cinders of stars such as our Sun, and contain a highly condensed form of helium, carbon and oxygen. The two white dwarfs in HM Cancri are so close together that mass is flowing from one star to the other. HM Cancri was first noticed as an X-ray source in 1999, showing a 5.4 minutes periodicity, but for a long time it has remained unclear whether this period also indicated the actual orbital period of the system. It was so short that astronomers were reluctant to accept the possibility without solid proof. '"
Censorship

North Korea's Own OS, Red Star 316

klaasb writes "North Korea's self-developed computer operating system, named 'Red Star,' was brought to light for the first time by a Russian satellite broadcaster yesterday. North Korea's top IT experts began developing the Red Star in 2006, but its composition and operation mechanisms were unknown until the internet version of the Russia Today TV program featured the system, citing the blog of a Russian student who goes to the Kim Il-sung University in Pyongyang."
Idle

Directed Energy Weapon Downs Mosquitos 428

wisebabo writes "Nathan Myhrvol demonstrated at TED a laser, built from parts scrounged from eBay, capable of shooting down not one but 50 to 100 mosquitos a second. The system is 'so precise that it can specify the species, and even the gender, of the mosquito being targeted.' Currently, for the sake of efficiency, it leaves the males alone because only females are bloodsuckers. Best of all the system could cost as little as $50. Maybe that's too expensive for use in preventing malaria in Africa but I'd buy one in a second!" We ran a story about this last year. It looks like the company has added a bit more polish, and burning mosquito footage to their marketing.
Wireless Networking

Submission + - How do real-world devices behave? Beyond 802.11

DrBob127 writes: Hello,

The purpose of this post is to ask for your insight and observations of the behaviour of actual Wi-Fi certified devices

My area of research has me interested in characterising the behaviour of Wi-Fi certified devices. More specifically, my immediate interested is in the decision of when a channel-change is initiated and the choice of which channel is selected to change to.

Having looked through the standard (IEEE Std 802.11(TM)-2007), I see that the decision to measure channel performance and the decision to initiate a channel switch is the responsibility of the station management entity (SME) [see figure 10-2]. The SME controls the MAC layer management entity (MLME) and the PHY layer management entity (PLME) which are both clearly defined by the standard to provide the mechanisms by which the channel can be measured and a channel switch carried out.

However, the SME is not defined by the standard (and I believe is left to vendors to implement) and it is here that the decision-making logic that I am interested in is located. This means that I am not going to find the answer to my question in the standard.

Restricting the discussion to devices operating in 'infrastructure-mode' (i.e. with an AP and subscriber STAs), I understand that only the AP can decide to switch channel. When an AP encounters a sufficiently degraded communication channel and assuming that all other channels are 'clear' which channel does the AP typically select to change to? If that channel is not available, which channel is then chosen?

However a STA may also initiate a channel scan if it loses connectivity to its AP. I am a member of a local WISP and during an outage I remember watching my home router (via its web-interface) channel-scanning to try and locate the tower. Starting from channel 1 the sequence of channels then went to 6, 11, 2, 7, 12, 3, 8 13, 4, 9, 5, 10, 1, 6..... Is this behaviour typical?

I look forward to your reply, thank you for your time and effort.

Slashdot Top Deals

This restaurant was advertising breakfast any time. So I ordered french toast in the renaissance. - Steven Wright, comedian

Working...