Posts Tagged ‘remote control’

How to decode infrared transmission

Thursday, April 22nd, 2010

rc5-decoding-explained.jpg

Alright, here we’re going for chapter on Manchester Encoding. Brian J Hoskins did just that when building this RC5 decoder. This protocol is widely used in television remote controls. You use them on a daily basis, don’t you think it’s time you understood what’s going on? Check out his writeup and learn the dark art of invisible light communication. Or just skip the learning and follow this how-to.

courtesy: Hack a day

Powering a switch via PoE

Wednesday, January 27th, 2010

poe-powered-switch.jpg

So the story goes like this, my roommate needed to tap some IP phones for diagnostic purposes. I found a netgear HUB that would serve that purpose. This was not ideal as the IP phone needed power from the network, or a 48V wall-wart. He asked if I could get PoE to pass through the hub. Easy, I’ll just loop the unused pair and viola! Wrong.

What really happened is I had to do a lot of reading, and found a few key things. According to 802.3 af standards, the PSE or Power Supply Equipment, decides how power is going to be sent, while the PD or Powered Device has to accept BOTH modes.

This might be a good time to explain that 802.3af can send power one of two ways. Using phantom power through pins 1,2,3 and 6 (mode A) or through the unused pairs, pins 4,5,7 and 8 (mode B). In all my testing, Cisco favors mode A power. Probably something about gigglebit standards?

[Kajer] was doing some work with IP phones that use Power over Ethernet. While trying to get this to work with a network switch he decided to use PoE to power the switch itself. The best thing about this is he managed to shoehorn all of the necessary bits into the stock case. Those bits include a bridge rectifier, transistor, resistor, and a 5v power supply. Along the way he discovered he can now power the switch off of USB if he wishes.

source: hackaday

Home Automation: Controlling Your House with Computers

Friday, December 26th, 2008

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We’ve looked at what you can do with home automation and what sort of methods exist for installing automated functionality, and now it’s time to take a look at some of the popular software applications out there for controlling your home automation system.

I haven’t included any software that ships with various systems in this list; you’ll find out about those when you’re looking at individual systems and deciding on one. What’s listed here are some well-respected and popular choices that enthusiasts around the world are using.

Source: Lifehack.org

How Gadgets Helped Mumbai Attackers

Wednesday, December 3rd, 2008

The Mumbai terrorists used an array of commercial technologies — from Blackberries to GPS navigators to anonymous e-mail accounts — to pull off their heinous attacks.

attacks

For years, terrorists and insurgents around the world have used off-the-shelf hardware and software to stay ahead of bigger, better-funded authorities. In 2007, former U.S. Central Command chief Gen. John Abizaid complained that, with their Radio Shack stockpile of communications gear, “this enemy is better networked than we are.” The strikes that killed at least 174 appears to be another example of how wired today’s “global guerrillas” can be.

As they approached Mumbai by boat, the terrorists “steered the vessel using GPS equipment,” according to the Daily Mail. A satellite phone was later found aboard.

Once the coordinated attacks began, the terrorists were on their cell phones constantly. They used BlackBerries “to monitor international reaction to the atrocities, and to check on the police response via the internet,” the Courier Mail reports.

The gunmen were able to trawl the internet for information after cable television feeds to the two luxury hotels and office block were cut by the authorities.

The men looked beyond the instant updates of the Indian media to find worldwide reaction to the events in Mumbai, and to keep abreast of the movements of the soldiers sent to stop them.

Outside of Leopold’s Cafe, “one of the gunmen seemed to be talking on a mobile phone even as he used his other hand to fire off rounds,” an eyewitness told The New York Times.

The terror group then took credit for the bloodshed with a series of e-mails to local media. They used a “remailer” service to mask their identities; earlier attacks were claimed from cyber cafes.

[Photo: AP; plugged in: CA, Giz]