technology mash

Driverless car: Behind the Scenes

2012-04-22T09:11:00.000+05:30

Google has created a vehicle capable of driving autonomously on roads. But as an engineer its more interesting to calculate the computations behind the scenes in the car.

Here's some explanation of what happens in the car:

A laser range finder mounted on the roof of the car generates detailed 3D map of the surroundings. Four radars, mounted on the front and rear bumpers, that allow the car to deal with fast traffic on roads; a camera, positioned near the rear-view mirror, detects traffic lights. GPS, inertial measurement unit, and wheel encoder, that determine the vehicle's location and keep track of its movements.

All these technologies work together to drive a car. Chris Urmson and Sebastian Thrun better explain the rest in the video, showing what the car does see as it moves.

Source: IEEE Spectrum

Aakash 2: worlds cheapest tablet

2012-04-14T10:56:00.001+05:30

Aakash is an Android-based tablet computer. The original Aakash had following configuration 7-inch resistive touch screen, ARM 11 processor, 256 MB RAM and a 2100 mAh battery. It has two USB ports.

Updated Aakash 2 has is about thrice faster with Cortex-A8 700 MHz processor. It also has a 3200 mAh battery and a capacitive touchscreen. Aakash will get also Android 4.0 update.

A review of Aakash:

Raspberry Pi: A credit card sized computer

2012-04-14T09:26:00.001+05:30

The Raspberry Pi is a single-board computer developed by the Raspberry Pi Foundation. It has an 700 MHz ARM11 processor, 256 MB RAM and uses SD card for storage.

It will be sold in two models.

Model A for $25
Model B for $35

Both model A and model B have the following features:

CPU: 700 MHz ARM1176JZF-S core (ARM11 family)
GPU: Broadcom VideoCore IV
RAM: 256 MB (SDRAM)
Video outputs: HDMI (rev 1.3 & 1.4), raw LCD Panels via DSI
Audio outputs: 3.5 mm jack, HDMI
Onboard storage: SD/MMC Card
Low-level peripherals: 8 × GPIO, UART, I²C bus, SPI bus with two chip selects
Power source: 5 volt via MicroUSB or GPIO header

Apart from the price difference the differences include

Model A:

1 USB 2.0 Port
No Ethernet port

Model B:

2 USB 2.0 Port
10/100 Ethernet (RJ45)

Raspberry Pi running Quake 3 game:

Introduction to Model B:

Google testing Augmented Reality Glasses

2012-04-05T18:39:00.000+05:30

As defined on Wikipedia, Augmented reality (AR) is a live, direct or indirect, view of a physical, real-world environment whose elements are augmented by computer-generated output such as sound or graphics. It can be considered an extension of Virtual Reality.

A video from Google..

Members of Project Glass Team at Google are testing augmented glasses.

The device features a band that stretches across the forehead and behind the ears, two nose pads, and a small rectangular screen that sits in front of the user's right eye. Required information will pop in real-time right in front of the user's eyes. The device presumably has built-in Wi-Fi and 3G/4G connectivity.

But every technology has disadvantages too..

Self Driving Car by Google

2011-03-06T10:23:00.001+05:30

Impossible is an anagram for I'm Possible.

The search enigne giant Google created a car that drives itself when instructed and lets you control the car when you feel so. Check the video below.

GATE 2011 Answer Key

2011-02-16T18:08:00.000+05:30

GATE 2011 answer key is available for

Click the above link to download the answer key in pdf format.

Hacking iPhone (iOS): Jailbreak and Unlock

2011-02-16T17:33:00.001+05:30

Hacking iOS installed on an iPhone is easier done than said.

These are two different things:

Jailbreak: Jailbreaking is done to install apps from non-Apple source (itunes App store) also called third-party apps.
Unlock: Unlocking is done to remove any operator lock that has been installed. So an AT&T locked iPhone sold in USA can be operated anywhere in the world on any operator network.

Jailbreaking an iPhone does not unlock it. But before Unlocking an iPhone, it needs to be Jailbroken.

Jailbreaking installs an App 'Cydia' on the iPhone. Cydia is used to add many features to iPhone.
Use the search feature of this app to install 'Ultrasnow'. Installing Utrasnow Unlocks the iPhone

Following both steps above makes an iPhone usable on any operator around the world.

Step-by-step tutorials for all versions of iOS are available here.

Latest hacks for iPhone and other devices can be found on Dev-Team blog.

Exynos processor: Samsung Orion

2011-02-12T16:57:00.001+05:30

Orion is just a codename of Samsung's ARM architecture based processor Exynos. The name is a combination of two Greek words Exypnos meaning smart and Prasinos meaning Green.

First model is the Exynos 4210, which is a dual-core 1GHz processor. It will be fabricated from March 2011 using 45 nm LP process of chip manufacture.

The SoC has quad-core Mali 400 GPU. It is capable of 1080p video decode, and also support DDR3 RAM.

It will interesting to devices, especially tablets based on this application processor.

Facebook Live Commenting [New Features]

2011-02-12T12:07:00.000+05:30

We spend time on Facebook to check out what our friends are doing. Watching photos and commenting on them. Things get interesting when people suddenly start commenting in large group, but what the hell, I need to refresh my page to see what the new comment is and wait for page reloads.

A terrible mess!

Facebook Engineering team is rolling out a new feature called Live Commenting It's like chatting on your instant messenger, no more page reloads. Just comment auto-loads behind the scenes.

When someone comments on your post or photo, the comments start loading automatically, without any page refresh! This is the magic of Javascript technology AJAX.

To achieve this the facebook team has tested, many technology approaches like:

Pushing vs. Polling Data
Write Locally, Read Globally

To understand the details of these processes, you can visit Facebook's Engineering team page.

Mobile Number Portability (MNP): Behind the scenes

2011-02-08T17:40:00.000+05:30

Mobile Number Portability allows swithcing between mobile phone operators without changing the mobile number. Sounds simple, but there are loads of tasks performed behind the scene at the operator end.

Few terms used:

SIM (Subscriber Identity Module):
- Securely stores IMSI number used to identify a mobile device.
IMSI (International mobile subscriber Identity):
- A 14-digit number that uniquely identifies for your sim card in entire world. It is used for routing calls to the user.
MSISDN (Mobile Subscriber Integrated Services Digital Network):
- Identifies the SIM card inserted in to the mobile phone
- MSISDN is mapped against the IMSI and the map is known by the SIM issuing network operator.
ICC-ID (Integrated Circuit Card ID):
- Every SIM is internationally identified by an unique ICC-ID. It is a 19-digit number printed behind the sim.

When you lose your SIM the operator demaps the MSISDN off the lost SIM's IMSI and maps it against a new IMSI. But the same thing can't be done for number portability as IMSI and MSISDN are network dependent and cross-mapping is not allowed.

When you port your number:

The new operator selects an unregistered MSISDN with its own network code.
This information is stored on MNP server along with new IMSI and ICC-ID.
This database is accessible by all networks.
On dialling a number, operator from which call originates queries the MNP server (centralized database) to get routing information for the call. The call is then completed with the new routing information.

The call routing can be illustrated as below:

For a number ported from mobile operator B to operator C.
If user from operator A calls, operator A seeks the routing information from MNP server.
If information is received, the call is routed according to new information, If no information is received, the call is routed as per the routing information of original operator.

Remove Facebook apps and/or enhancing your privacy settings

2011-02-06T18:10:00.000+05:30

I used about 135 apps some time in past. Currently I use only 15 of those apps. That translates to free access to my private data (photos etc) for 120 unnecessary apps! Mind you some of these apps were also spammy.

Some applications on Facebook platform have access to your private data when you are logged out.

There is a way to remove these apps from your profile. Else you might end up seeing your profile on a dating website some day.

The steps are as follows:

Click on Accounts -> Privacy Settings at top right corner

On following page, click on 'Edit your settings' under Apps and Settings at the bottom left corner

The following page will display the number of Apps you use. Click 'Remove' unwanted and spammy apps

The following page shows all the apps that have access to your personal information.

To remove an app directly click the 'x' in front of that application

To tweak privacy settings for a particular application, click on 'Edit Settings' in front of the application.

The interface will expand as shown below and you can tweak access as necessary.

Congrats you have just avoided misuse of your facebook account.

Android 3.0, Honeycomb- Awesome Tablet OS

2011-02-06T16:24:00.001+05:30

Android 3.0 is a new version of the Android platform optimized for tablets.

The video below tells more than words can express.

The improvements include:

Users can switch between text/voice input modes from a button in the System Bar
Users can also connect full keyboards over either USB or Bluetooth, for a familiar text-input environment
Built-in support for Media/Photo Transfer Protocol lets users instantly sync media files with a USB-connected camera or desktop computer
New multitouch support is now available to JavaScript and plugins
Redesigned Camera application to take advantage of a larger screen for quick access to exposure, focus, flash, zoom, front-facing camera
Multiple tabs replace browser windows and a new “incognito” mode allows anonymous browsing

WiFi Direct: wireless LAN standard for file sharing

2010-10-26T15:44:00.006+05:30

So, you want to share large folders like videos, photos fast but without wires??

Creating a wireless LAN to share files between computer was difficult and almost impossible for non-geeks.

Few months back I wanted to share 5 GB of photos in my laptop with a friend. Few minutes later I was disappointed to know that its impossible over existing WiFi architecture. The other option was bluetooth, but it is very slow. Finally I used to the old method of transferring files using a flash drive.

But wireless file sharing over WiFi is now possible using the WiFi direct standard.

Wi-Fi Direct acts like a software hotspot (software access point, or "soft AP"), for any device that wishes to support it. All Wi-Fi Direct connections are protected by the recent WPA2 security standard. When a device enters the range of the Wi-Fi Direct host, they can connect using the existing ad-hoc protocol and create a connection.

Atleast one Wi-Fi Direct enabled device is needed to perform the task. Any Wi-Fi Direct enabled device can connect to other non Wi-Fi Direct certified devices to perform the task.

Turn off Bluetooth by default in Linux

2010-10-23T10:40:00.000+05:30

Many people noticed that bluetooth is switched on by default laptop on a laptop running Ubuntu. One method on internet is to stop bluetooth module from loading, but that method prevents from using bluetooth when needed. This can also be used on other Debian based Linux distros with bluetooth enabled by default.

Lets see how to configure it.

Open the Terminal (Applications -> Accesories -> Terminal)

At the prompt, type

sudo nano /etc/rc.local

add following line before the last line exit 0 (highlighted in the screenshot).

rfkill block bluetooth

This is how it works:

Scripts in file /etc/rc.local are executed at the end of all the multi-user boot levels.

Adding

rfkill block bluetooth

turns off bluetooth after the OS starts it.

rfkill provides a generic interface to disabling any radio transmitter in the system.

This helps in reducing the power consumption of a computer and also protects us from wireless radtion.

Switch (Basics)

2010-10-23T06:40:00.001+05:30

Switch is an electrical component that can make or break an electrical circuit. It has conductive pieces (often metal) called contacts or terminal that touch to close (make) or open (break) a connection.

A pair of contacts is closed (switched on) when current can flow from one contact to other. When the contacts are separated by an air gap, they are open (switched off) and no current can flow between them.

Switches used for home wiring are mechnical switches and have an internal arrangement as shown below.

Electromechanical switches like relay are used for specialized operations.

Note: The representation shown below is the technical representation (used in diagrams) followed by some actual switches used.

Technically, based on the number of contacts, switches can be classified as:

SPST (Single pole, single throw)

It is a simple on-off switch. The two terminals are either connected together or disconnected from each other.

For Ex: light switch in homes.

SPDT (Single pole, double throw)

It has a common contact C (COM) connected to either of two other contacts A or B.

SPCO (Single pole, centre off)

Equivalent to SPDT switch, only that it has a centre off position.

DPST (Double pole, single throw)

Equivalent to two SPST switches controlled by a single mechanism.

DPDT (Double pole, double throw)

Equivalent to two SPDT switches controlled simultaneoulsy.

A is connected to either B or C, D is connected to either E or F.

DPCO (Double pole, centre off)

Equivalent to a DPDT switch, it has a stable off position in the centre.

Switches derived from above are switches are

Push-to-make

A push-to-make switch returns to its normally open (off) position when you release the button, this is shown by the brackets around ON.

For Ex: Doorbell switch.

Push-to-break

A push-to-break switch returns to its closed (on) position when you release the button.

Source: Wikipedia