Nov 24, 2015

Raspberry Pi 2 : Getting started

Not having played around with Linux for a long time, I finally decided to set up a Raspberry Pi 2 project. For $35, this tiny computer does pack a punch. This spec sheet details out everything. You can basically set up a small web, mail, or home automation server and more.

My idea was to turn it into a VPN gateway that sits between my TV and home router and serve up a US IP through OpenVPN. This will basically let me stream Netflix or Hulu directly on the TV, without the need of Miracast or DLNA devices/software.

Having dabbled with OpenVPN and basic routing when setting up my VPS, this was fairly straightforward. I was inspired by this Makezine guide, which used two Wifi dongles - one for connecting to the local network and the other for hosting the VPN access point. Picking the correct dongles is also important; it would need to support the soft AP function. I used an Edimax EW-7811 Un and a Tenda W311MI. Both are fairly cheap and robust, although the Edimax one seems to drop a lot of packets.

In addition to stock Raspbian (a Debian-based distro, optimized for Raspberry Pi), you would also need to install hostapd which will turn the dongle into an AP and also dnsmasq for basic DHCP and DNS for clients connecting to the AP. Once done, you would need to use iptables to do the routing, which basically takes the traffic from the wifi subnet and forwards it to the VPN tunnel. Any client connecting to the AP will have a public IP address of the VPN server.

Performance in terms of VPN throughput remains a concern. My Android phone, connected to the VPN directly, gives 18 Mbps down, whereas the Raspberry AP only gives 3 Mbps. Many discussions suggest this could be due to a bottleneck, as the Ethernet and USB ports share the same interface and the traffic has to traverse the bus twice. Switching the inbound interface from USB to Ethernet didn't improve the situation either; some commenters also suggest that the CPU itself could be a problem. However, 'top' didn't reveal much load on the CPU.

3 Mbps is barely enough to provide a SD stream, so HD is pretty much impossible. Still needs some digging around to identify where the bottleneck is. Even so, I would consider this project a 'fruit'ful one.

With the case open

Up and running

Jan 31, 2011

Kindle 3G - First impressions

Finally, after months of waiting, I have the Kindle 3G in my hands. And it has been well worth the wait.

The screen is a pleasure to read from, coming almost close to a printed book in terms of resolution and sharpness. Having read an e-book for more than an hour in a sitting, I came out of it without a headache or eyestrain. The Kindle truly delivers on Amazon's promise that within a few page turns (virtual, of course), you will disappear into the book. I know I did.

The experimental web browser is just that, experimental. The pages take some time to load, but it helps if images are turned of and you are reading the mobile version of the page. But then again, I didn't buy it for browsing the web, and it is more than a nice-to-have.

I only wish that Amazon brings down the Kindle book prices than their physical copies, still can't see the rationale of a digital copy costing as much as the real thing. However, if you are a bibliophile and can't have enough of the printed word, the Kindle is the best gift you could buy yourself.

Jun 26, 2009

Sixth Sense - Virtual information, real world

Augmented reality finally seems to be coming to the real world. In an amazing demonstration of the possibilities, Pranav Mistry and Patti Maes of MIT Media Lab show how simple off-the-shelf components can be put together to make your own wearable gestural interface.

Called Sixth Sense, the device consists of a camera, a pocket projector with mirror and a mobile phone. The phone remains in the user's pocket, and uses visual input from the camera and the projector acts as the monitor. It can be programmed to recognise hand gestures and virtually any surface can be used as a screen.

With these basics in place, Sixth Sense can seamlessly plug in information from the virtual world to the real world. For example, a person browsing through a new bestseller at a bookstore can project Amazon ratings and reader reviews right onto the book and make instant decisions on whether to buy the book or not. You can check your flight timings by just holding the ticket in front of the camera. The system will scan the ticket and retrieve the current status from the Web, through the mobile phone's data connection.

An extremely interesting application of ubiquitous technologies, Sixth Sense has amazing potential to change how we see and interact with the world around us. By supplementing the real world with meta information and an easy-to-use interface, this is one technology that really lives up to its name. [Sixth Sense demo]