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.

DTMF (Dual Tone Multiple Frequency):

In telecommunication, a caller needs to dial the number of the callee. The earlier versions of telephones used to have rotary type dials which are now obsolete. Almost all the landline and mobile phone handsets now use pushbutton keypads.

What is DTMF?
DTMF is a signalling system for identifying the keys or better say the number dialled on a pushbutton or DTMF keypad. The early telephone systems used pulse dialling or loop disconnect signalling. This was replaced by multi frequency (MF) dialling. DTMF is a multi frequency tone dialling system used by the push button keypads in telephone and mobile sets to convey the number or key dialled by the caller. DTMF has enabled the long distance signalling of dialled numbers in voice frequency range over telephone lines. This has eliminated the need of telecom operator between the caller and the callee and evolved automated dialling in the telephone switching centres.

DTMF (Dual tone multi frequency) as the name suggests uses a combination of two sine wave tones to represent a key. These tones are called row and column frequencies as they correspond to the layout of a telephone keypad.

A DTMF keypad (generator or encoder) generates a sinusoidal tone which is mixture of the row and column frequencies. The row frequencies are low group frequencies. The column frequencies belong to high group frequencies. This prevents misinterpretation of the harmonics. Also the frequencies for DTMF are so chosen that none have a harmonic relationship with the others and that mixing the frequencies would not produce sum or product frequencies that could mimic another valid tone. The high-group frequencies (the column tones) are slightly louder than the low-group to compensate for the high-frequency roll off of voice audio systems.

The row and column frequencies corresponding to a DTMF keypad have been indicated in figure.

DTMF tones are able to represent one of the 16 different states or symbols on the keypad. This is equivalent to 4 bits of data, also known as nibble.

QR Codes, Barcodes and RFID:

QR Codes, barcodes and RFID (radio frequency identification) are all systems for conveying large amounts of data in a small format. They offer speed, labor savings and cost savings, among other benefits. But there are distinct differences between all 3 — and differences in the purposes they are best suited for.

QR CODES
A recent trend among small businesses is the growing use of QR codes. QR codes are similar in one sense to bar codes, in that they contain information which can be read by a QR code reader.

QR codes can be scanned and read by a camera-equipped smartphone when you’ve downloaded a scanner app, such as i-nigma for the iPhone. What this means is that the average person can now de-code (read) a QR code, without special equipment. You could walk into a place of business, see a QR code on an item, scan it with your smartphone, and immediately have access to a lot of information electronically.

BARCODES
Barcodes have been around for decades. They are versatile with a large variety of uses — especially in retail and manufacturing settings, and in transport and shipping.

We’re used to seeing the common barcode printed on packaging at the grocery store or in other retail outlets, when items are passed over the barcode reader at the checkout counter to ring up a sale. Barcodes not only are valuable at the point of sale, but also for managing inventory and raw materials internally, so that you know what you have in stock.
Barcodes are relatively inexpensive, and help drive speed, efficiency and profitability.

RFID
RFID (radio frequency identification) has likewise been around for decades. However, RFID tends to require more technological hand-holding. RFID involves applying RFID tags to items or boxes or pallets. Tags vary greatly in size, shape and capabilities, but one example is pictured below. The tag with its small antenna emits a radio frequency signal that is picked up and read by a special wireless RFID reader, conveying information from the tag about the item it is affixed to.

RFID is adaptable to many of the same uses that barcodes are good for. But RFID is especially useful in situations where vast quantities of goods must be moved or tracked, or where tracking of item-specific information is necessary. RFID has been mandated by some customers, such as Wal-Mart and the Department of Defense, to track the vast quantities of items they require in their supply chains and to supply much more detailed information. In such situations, RFID maybe able to do it more quickly, effectively and efficiently than barcodes.

RFID, barcodes and QR Codes all have their place for different purposes and under different circumstances. As with most technology, the cost to acquire and use it keeps coming down with each passing year. All 3 of these data management systems also have gotten much easier to implement in the past few years

What is a SIM card and why is it so important?

In the world of mobile phones, there are two primary phone types that are available to consumers: GSM (Global System for Mobile Communication) and CDMA (Code Division Multiple Access). GSM phones are the ones that utilize SIM cards while CDMA phones do not.
SIM cards are the small cards which contains a chip that must be inserted into GSM phones before they will work. Without a SIM card, a GSM phone won’t be able to tap into any mobile network. The card is what holds all of the critical information.

For comparison sake, CDMA carriers keep a list of all phones that are allowed to use their network. Phones are tracked by their ESN (electronic serial number) so they do not require SIM cards. Once activated, a CDMA phone is tied directly to that particular carrier’s network.

The important part is a small integrated chip which is able to be read by the mobile device it is inserted into, and contains a unique identification number, the phone number and other data specific to the user it is registered to.

The SIM also contains a small amount of memory which can store up to 250 contacts, some SMS messages and other information used by the carrier who supplied the card. A SIM card can usually be removed from one handset and inserted into any other compatible handset, allowing the user to switch devices without losing their contacts data, having to change their phone number or start a new mobile contract. This isn't generally possible if the cell phones originated in different countries, as cellular network frequencies vary between countries.

In many countries, SIM cards and handsets are locked to the carrier they are purchased from. This means that although a SIM card from a carrier will work in any handset sold by that same carrier, it will not work in a handset sold by a different carrier. It is usually possible to unlock a cell phone with help from the carrier.

SIM Card Sizes:

The SIM card size that most people use is called the Mini SIM, but Micro SIM cards are increasingly being used in mobile devices, including some models of the iPhone and the Samsung Galaxy S3. The first SIM cards were roughly the size of a credit card, and many Mini SIM's are still supplied with this large, Full SIM surround. Both Mini and Micro SIM cards feature a cut off corner to help prevent incorrect insertion into the phone or tablet. You can see the dimensions of the different types of SIM card below.

Full SIM - 85mm x 53mm
Mini SIM - 25mm x 15mm
Micro SIM - 15mm x 12mm
Nano SIM - 12.3mm x 8.8mm

Despite differences in size, all SIM cards contain the same types of identifying numbers and information on the small chip. Different cards do contain different amounts of memory space, but this has nothing to do with the physical size of the card. A mini SIM can actually be trimmed down using scissors to turn it into a micro SIM, as long as it is only the plastic surround which is cut.