goTenna

goTenna enables you to communicate without any need for central connectivity whatsoever—no cell towers, no wifi, no satellites—so when you're off-grid you can remain connected. In fact, goTenna will even work if your smartphone is in “Airplane Mode”! 

How does this magic work?
Pair your smartphone to your goTenna device wirelessly, using Bluetooth-LE. Your goTenna needs to be within 20 feet of your phone, so that the two can communicate with each other. Use our free app to type out a text message or share a location. Your smartphone will send the message to your goTenna, which will then shoot it out, via long-range radio waves (151-154 MHz), to the intended goTenna(s).
At the other end, the exact same thing happens, in reverse: the recipient goTenna sends your message over Bluetooth-LE to the smartphone app it's paired with. All of this happens in a matter of milliseconds, and your goTenna will be able to transmit to any goTenna within range.

What kind of range can you expect?
The most important thing to understand about range with goTenna is that it is greatly dependent on your geography: specifically your terrain and elevation.
Next, there are two distinct ways to answer this question.

What is the theoretical range?
The first approach is to use industry-standard radio-frequency propagation calculators that assume ideal conditions.

What is the more likely range?
When you don't find yourself at the edge of cliff or hanging out in a skyscraper, your range with goTenna will be smaller. Most of the time you'll probably be trucking your boots through the dirt with land (or water) all around and level with you, and the goTennas you and your friends are using to communicate with are probably going to be 4-6 feet off the ground.

So your range with goTenna will look more like this in those more common scenarios:
City street to city street: 0.5-1 mile
Forest to forest: 2-3 miles
Water to water: 4-6 miles
Desert to desert: 4-6 miles
 Can you get more than this when you're on the ground? Absolutely. We wouldn't be surprised if you did a lot better. But we want to be the first honest radio company, so we'd rather under-promise and over-deliver.

How can you improve your range?
As you probably get by now, elevating the goTenna increases its range drastically. Hike up a little, hang it from a tree, etc. But another way to improve your range when you can't elevate yourself significantly—or even when you can—is to attach it externally to other gear (e.g. a backpack), as opposed to having it at the bottom of a bag. That's what the nylon attachment strap is for!

Key app features
Send & receive text messages for free
Share locations on detailed offline maps
Instantaneous transmission within range
Automatic message retry & delivery confirmation
Individual & group messaging
”Shout” broadcasts to anyone within range
Proximal friend map & location pinging
Emergency chat
End-to-end encryption (RSA-1024) & self-destructing messages
Compatible with iOS & Android

Key hardware specs
Antenna
2-watt radio
Flash memory good for 1000’s of messages
Rechargeable Lithium-ion battery
Micro-USB connector
BluetoothLE data interface
Status indicator lights
Nylon attachment strap
Water-resistant
Dust-tight

Indian inventor builds his own version of Google Glass for Rs. 4,500

Arvind Sanjeev from India has built a makeshift Google Glass replica for Rs. 4,500 in less than a month.

Arvind Sanjeev from Kochi India has made a makeshift Google Glass replica “Smart Cap” in a month for Rs. 4,500. Arvind made the replica using a USB webcam, a Raspberry Pi board, an LCD panel, aspheric lens, headphones, sun board sheet and glue.

The “Smart Cap” runs on open Android and includes a Raspberry Pi board and a 2.5inch LCD screen which is mounted on the cap. For the eyepiece Arvind has used an aspheric lens to make the screen visible from such close distance. And with the help of mic'ed headphones the device responds to voice commands as well.

Arvind has put this project on his DIY profile and given steps to make it, so that enthusiasts who are interested in the project could make their own. Arvind has devised many other things besides this “Smart Cap” and all his projects are available as DIY tutorials.

Arvind who has his own startup A.R.S devices has developed many innovative devices and products in the field of automation, connected devices and safety. Arvind has also applied for a patent for hardware he has developed with which you can control your car through a mobile app.

ISM band and Applications

The ISM (industrial, scientific and medical) radio bands were originally reserved internationally for the use of RF energy for industrial, scientific and medical purposes other than communications. Examples of applications in these bands include radio-frequency process heating, microwave ovens, and medical diathermy machines. The powerful emissions of these devices can create electromagnetic interference and disrupt radio communication using the same frequency, so these devices were limited to certain bands of frequencies.

ISM Uses:

The most commonly encountered ISM device is the home microwave oven operating at 2.45 GHz.

Many industrial settings may use ISM devices in plastic welding processes.

In medical settings, shortwave and microwave diathermy machines are ISM devices mostly commonly used for muscle relaxation. Microwave ablation, a type of interventional radiology, is an ISM application which treats solid tumors through the use of RF heating.

Some electrodeless lamp designs are ISM devices, which use RF emissions to excite fluorescent tubes. Sulfur lamps are commercially available plasma lamps, which use a 2.45 GHz magnetron to heat sulfur into a brightly glowing plasma.
Long-distance wireless power systems have been proposed and experimented with which would use high-power transmitters and rectennas, in lieu of overhead transmission lines and underground cables, to send power to remote locations.
NASA has studied using microwave power transmission on 2.45 GHz to send energy collected by solar power satellites back to the ground.
Also in space applications, a Helicon Double Layer ion thruster is a prototype spacecraft propulsion engine which uses a 13.56 MHz transmission to break down and heat gas into plasma.

Non-ISM uses

In spite of the real purpose of ISM bands, there has been rapid growth in its use in low-power, short-range communications platforms.

In recent years ISM bands have also been shared with (non-ISM) license-free error-tolerant communications applications such as wireless sensor ne0tworks in the 915 MHz and 2.450 GHz bands, as well as wireless LANs and cordless phones in the 915 MHz, 2.450 GHz, and 5.800 GHz bands.

Wireless LAN devices use wavebands as follows:

• Bluetooth 2450 MHz band falls under WPAN
• HIPERLAN 5800 MHz band
• IEEE 802.11/WiFi 2450 MHz and 5800 MHz bands

Google's Project Loon uses ISM bands (specifically 2.4 and 5.8 GHz bands) for balloon-to-balloon and balloon-to-ground communications.

several brands of radio control equipment use the 2.4 GHz band range for low power remote control of toys, from gas powered cars to miniature aircraft.
Worldwide Digital Cordless Telecommunications or WDCT is a technology that uses the 2.4 GHz radio spectrum.

PIXEL

The term "pixel" is actually short for "Picture Element." These small little dots are what make up the images on computer displays, whether they are flat-screen (LCD) or tube (CRT) monitors. The screen is divided up into a matrix of thousands or even millions of pixels. On color monitors, each pixel is actually composed of three dots -- a red, a blue, and a green one.

Typically, you cannot see the individual pixels, because they are so small. This is a good thing, because most people prefer to look at smooth, clear images rather than blocky, "pixelated" ones. However, if you set your monitor to a low resolution, such as 640x480 and look closely at your screen, you will may be able to see the individual pixels. As you may have guessed, a resolution of 640x480 is comprised of a matrix of 640 by 480 pixels, or 307,200 in all. That's a lot of little dots.

In the picture below is an example of a close up of pixels on a LCD screen. As can be seen in the picture, we've zoomed into the "eye" part of the eagle to give a better understanding of how the display works. Each pixel is made up of a red, green, and blue (RGB) light that is increased or decreased in intensity to make up each of the colors you see on the screen.

Each pixel can only be one color at a time. However, since they are so small, pixels often blend together to form various shades and blends of colors. The number of colors each pixel can be is determined by the number of bits used to represent it. The number of bits used to represent each pixel determines how many colors or shades of gray can be displayed. For example, in 8-bit color mode, the color monitor uses 8 bits for each pixel, making it possible to display 2 to the 8th power (256) different colors or shades of gray.

 However, at 16, 24, and 32-bit color depths, the color blending is smooth and, unless you have some kind of extra-sensory vision capability, you should not see any graininess.

Mega Pixel
A megapixel (MP) is a million pixels; the term is used not only for the number of pixels in an image, but also to express the number of image sensor elements of digital cameras or the number of display elements of digital displays.

For example, a camera that makes a 2048×1536 pixel image (3,145,728 finished image pixels) typically uses a few extra rows and columns of sensor elements and is commonly said to have "3.2 megapixels" or "3.4 megapixels", depending on whether the number reported is the "effective" or the "total" pixel count

Large (3072 x 2304 pixels) -- 7 megapixels
Medium (2048 x 1536 pixels) -- about 3 megapixels
Small (640 x 480 pixels) -- .3 megapixels

E-WASTE RECYCLE:

1. 80 to 85% of electronic products were discarded in landfills or incinerators, which can release certain toxics into the air.

2. 20 to 50 million metric tons of e-waste are disposed worldwide every year.

3. Cell phones and other electronic items contain high amounts of precious metals like gold or silver. Americans dump phones containing over $60 million in gold/silver every year.

4. For every 1 million cell phones that are recycled, 35,274 lbs of copper, 772 lbs of silver, 75 lbs of gold, and 33 lbs of palladium can be recovered.

5. Recycling 1 million laptops saves the energy equivalent to the electricity used by 3,657 U.S. homes in a year.

6. It takes 539 lbs of fossil fuel, 48 lbs of chemicals, and 1.5 tons of water to manufacture one computer and monitor.

7. Electronic items that are considered to be hazardous include, but are not limited to:Televisions and computer monitors that contain cathode ray tubes, LCD desktop monitors, LCD televisions, Plasma televisions, Portable DVD players with LCD screens.

8. Only 12.5% of e-waste is currently recycled.

9. E-waste is still the fastest growing municipal waste stream in America, according to the EPA.

10. A large number of what is labeled as "e-waste" is actually not waste at all, but rather whole electronic equipment or parts that are readily marketable for reuse or can be recycled for materials recovery.