Wireless window contacts -- no maintenance, no batteries

Window contacts tell us which of a house’s windows are open or closed. Researchers have now developed a fail-safe system that is particularly easy to use and needs no wiring or batteries. The sensors harvest the energy they need to run from ambient radio signals.

It is 7:30 a.m. and high time she left the house; she mustn’t be late for her 8 o’clock appointment. But the young lady still feels the need to check that she closed all her windows, because the forecast is for thunderstorms that afternoon. Later, in the car, she realizes that she forgot to check one of the rooms when she went round the house. In situations like this, window contacts can make life easier and give peace of mind. These little electronic helpers are fitted onto window handles, and they can tell from the position of the handle whether the window is wide open, tilted open or closed. They transmit this information to a base station, and the house’s occupants can then see at a glance which windows are open.

Research scientists at the Fraunhofer Institute for Microelectronic Circuits and Systems IMS in Duisburg have now developed a version of this sensor arrangement that is particularly reliable and easy to use and which needs no wiring or batteries. “Our wireless window contacts draw all their energy from ambient radio signals,” explains Dr. Gerd vom Bögel, a scientist at the IMS. Until now, wireless models have been reliant on either batteries or solar cells, but both of these approaches have drawbacks. Batteries need to be changed regularly to keep window contacts operational. Solar-powered systems avoid this problem, but they too are liable to fail: all it takes is for the sunlight to be blocked by something casting an unintentional shadow over the solar cell. Solar systems are also aesthetically less pleasing because they cannot be tucked away in a dark corner of the window. Which leaves the classic setup: window contacts with cable connections. Such systems have been on the market for years. The main argument against these is the effort it takes to install them – quite apart from the fact that it is often impossible to retrofit them to existing buildings.

The new system, however, can be fitted with little effort – and they can be positioned very discreetly. Aside from window contacts, each room is equipped with a room controller. This transmitter module not only receives the data from individual window contacts, it also actively provides the sensors with energy via its radio signal. The room controller also has the function of passing the sensor data on to a central base station in the building, from which users can query the status of all windows. Alternatively, the system can be configured to permit remote querying, for instance from a user’s smartphone. The only prerequisite for this is a DSL connection for the base station.

Energy management was the issue which caused the most headaches during development. “Room controllers, too, have to comply with certain limits on the strength of their radio output. This makes it particularly tricky to get enough energy to all the window contacts in bigger rooms,” vom Bögel points out. “But we have made sure all the sensor modules, antennas and components are so finely tuned to each other that the system works reliably even over considerable distances.”

The IMS research scientists have already constructed an initial prototype, and they know which way they want to head next: They are hoping to integrate other types of sensor into the system along the same lines – to regulate room temperature, for example. At the moment, thermostats are generally fitted somewhere just inside the room. If a door is open, the temperature by the door will be lower than in the middle of the room. As a result, the thermostat will then unnecessarily regulate the temperature upwards. The new system would allow a temperature sensor to be placed unobtrusively precisely where a particular temperature is desired – for instance on the display cabinet by the dining room table.

Source: http://www.physorg.com/

(© Fraunhofer IMS)

Direct-To-Home (DTH) Technology

Overview

Direct to home technology refers to the satellite television broadcasting process which is actually intended for home reception. This technology is originally referred to as direct broadcast satellite (DBS) technology. The technology was developed for competing with the local cable TV distribution services by providing higher quality satellite signals with more number of channels.

In short, DTH refers to the reception of satellite signals on a TV with a personal dish in an individual home. The satellites that are used for this purpose is geostationary satellites. The satellites compress the signals digitally, encrypt them and then are beamed from high powered geostationary satellites. They are received by dishes that are given to the DTH consumers by DTH providers.

Though DBS and DTH present the same services to the consumers, there are some differences in the technical specifications. While DBS is used for transmitting signals from satellites at a particular frequency band [the band differs in each country], DTH is used for transmitting signals over a wide range of frequencies [normal frequencies including the KU and KA band]. The satellites used for the transmission of the DTH signals are not part of any international planned frequency band. DBS has changed its plans over the past few years so as to include new countries and also modify their mode of transmission from analog to digital. But DTH is more famous for its services in both the analog and digital services which includes both audio and video signals. The dishes used for this service is also very small in size. When it comes to commercial use, DBS is known for its service providing a group of free channels that are allowed for its targeted country.

How DTH Works

To know the working of DTH better, take a look at the diagram below.

For a DTH network to be transmitted and received, the following components are needed.

* Broadcasting Centre

* Satellites

* Encoders

* Multiplexers

* Modulators

* DTH receivers

It must be noted the channels that are broadcasted from the broadcasting centre are not created by the DTH providers. The DTH providers pay other companies like HBO, Sony MAX and so on for the right to broadcast their channel to the DTH consumers through satellite. Thus the DTH provider acts as a mediator r broker between the consumers and the programme channels.

The broadcast centre is the main part of the whole system. It is from the broadcast station that the signals are sent to the satellites to be broadcasted. The broadcast station receives the signals from various program channels.

The satellite receives the signal from the broadcast centre and compresses the signals and makes them suitable for re-transmission to the ground.

The DTH providers give dish receivers for the viewers to receive the signal from the satellites. There may be one or multiple satellites that send the signals at the same time. The receiver receives the signal from them and is passed on to the Set Top Box [STB] receiver in the viewer’s house.

The STB receiver changes the signal in a form suitable for our television and then passes it on to our TV.

Advantages of DTH Technology

* The main advantage is that this technology is equally beneficial to everyone. As the process is wireless, this system can be used in all remote or urban areas.

* High quality audio and video which are cost effective due to absence of mediators.

* Almost 4000 channels can be viewed along with 2000 radio channels. Thus the world’s entire information including news and entertainment is available to you at home.

* As there are no mediators, a complaint can be directly expressed to the provider.

* With a single DTH service you will be able to use digital quality audio, video and also high speed broadband.

LED TV Vs LCD TV

There are some differences that should be noted in the issue of LED TV vs. LCD TV. For starters, a traditional LCD television was created to use florescent lighting or another form of flat lighting while an LED TV will make use of a diode that emits light through an LCD panel. Furthermore, there are a number of different lighting styles within both LED and LCD TVs. For instance, some models contain an LED light panel located behind the LCD panel. In other models, LED lights are found around the outer rim of the screen. While in other models LED lights are tricolored and can be controlled in a way that will allow the picture to have stronger contrasts with blacks and bright colors. This feature is known as local dimming which is ultimately what makes the LED TV so different from traditional LCD television.

Picture Differences between LED TV Vs LCD TV

When a traditional LCD television is in operation, the backlight is always on. LCD televisions create dark areas in contrast by twisting crystals to a closed position to block light. This method provides fewer details in dark areas of the screen by offering a small contrast ratio. The local dimming of LED technology will correct the lower quality dark areas in LCD television. Since the LED diodes that control the lights in this technology are capable of being dimmed rather than blocked, higher details in darker areas of the picture are created. Therefore, LED TV Vs. LCD TV will find a greater advantage in the local dimming possibility of LED technology, simply for the higher contrast providing a detailed picture, and displaying more realistic color.

Life of LED and LCD TV

Another consideration in the LED TV Vs. LCD TV issue is the lifetime of the two television technologies. Many manufacturers will claim that their model will produce roughly 100,000 hours of life. However, since LED is still fairly new there is little data that states the length of the lifecycle of this television. Also model, manufacturer, and type of LED technology can play an important part in determining lifespan. It is true to say that since LED TV technology displays a better picture, there are a larger number of LCD TVs with this technology being produced than traditional LCD television. As this continues it is safe to say that the lifespan of an LED TV will become increasingly longer as it’s popularity continues grows.

Differences in Power Consumption of LED and LCD

In LED TV Vs. LCD TV is important to mention that the LED diodes used in local dimming will consume more power than traditional LCD televisions of the same size. In fact, the local dimming LED technology uses almost as much power as a plasma television. However, although the traditional LCD TV uses less power than the local dimming LED TV technology, it is also true to say that the white edge lit LED technology (LED lights located around the edge of the screen) uses less power than both LCD TV, and local dimming LED TV.

LED Television Technology

What is LED Backlight TV?

LED (Light Emitting Diode) TVs are basically LCD TVs that use a LED backlight system to illuminate the LCD screen. There are two methods to accomplish this:

1) LED edge lighting (Edge lit): In this method, LED lights are placed around the perimeter (sides) only. This allows for a slimmer TV design.

2) LED Backlight (Array lit): In this method, LED lights are placed in the form of an array (across the whole back of the display). Any of the lights can be turned off to correspond with the scene being displayed, and this is why it can project such an accurate picture.

What makes LED TVs better than traditional LCD TVs?

The advantages include:

Superior picture quality

LED TVs will produce deeper blacks due to “local dimming” technology. In comparison, LCD TVs produce a lower picture quality, especially when projecting dark backgrounds. The Cold Cathode Fluorescent Lamp (CCFL), which is located behind the screen, does not actually remain cool. Instead of using all of its energy to produce light, it wastes energy in the form of heat. Further, since the CCFL current flow must be kept at a high level to preserve its lifespan, LCD screens cannot be easily dimmed. This is one of the reasons why LED TVs can operate more efficiently while providing a more precise image quality.

Slim design

LED TVs have an ultra-thin design because of the LED backlight technology. This design makes it easy to mount your LED television on the wall to save space.

Power efficiency

LED TVs use less power than plasma and traditional LCD TVs. In fact, Samsung states that their TVs use 40% less power than a conventional TV. Switching to a LED TV will save you money on your monthly electrical bill and waste less energy on producing heat.

Eco-friendly

LED TVs are considered to be more environmentally friendly than fluorescent tubes because LED bulbs are mercury and lead free. LED TVs can also operate for longer hours (15 times longer than ordinary bulbs). The overall lifespan is much longer than your average TV.

Given that it is still relatively new and that it is a superior technology, LED TVs are a little more expensive than plasma and LCD TVs. Samsung, a leader in the TV industry, has a wide range of LED TVs that range from $1,600 – $3,200 depending on the size.

LCD Television Technology

Introduction to LCD Television

Like the popular flat panel LCD monitors that are now commonly used with computers, LCD Televisions have a slim design and a flat viewing surface, but have been fine tuned for video and television display. Recent advances in flat panel LCD television technology now allow for larger screens, wider viewing angles, and higher-quality video images. LCD Televisions are also competing with plasma television technology. They are several times lighter than comparably sized plasma televisions, and are far more durable.

All LCD Televisions offer progressive scan displays and sleek, slim designs. They also provide users with a bevy of input options, adding to their versatility. Most LDC televisions double as computer displays by allowing standard analog VGA (PC) or even DVI digital input, a great option if you need your LCD Television to pull double duty as a PC monitor. Nearly all LCD Television sets offer the option to mount on a wall, under a cabinet, on on a desktop.

How LCD Televisions Work

An LCD Television is sometimes referred to as a "transmissive" display—light isn't created by the liquid crystals themselves; a light source behind the panel shines light through the LCD Television display. A white diffusion panel behind the LCD redirects and scatters the light evenly to ensure a uniform image.

The LCD television display consists of two polarizing transparent panels and a liquid crystal solution sandwiched in between. The screen's front layer of glass is etched on the inside surface in a grid pattern to form a template for the layer of liquid crystals. Liquid crystals are rod-shaped molecules that bend light in response to an electric current — the crystals align so that light cannot pass through them. Each crystal acts like a shutter, either allowing light to pass through or blocking the light. The pattern of transparent and dark crystals forms the image. It's the same display technology behind your digital watch but way more sophisticated.

LCD Televisions typically use the most advanced type of LCD, known as an "active-matrix" LCD. This design is based on thin film transistors (TFT) — basically, tiny switching transistors and capacitors that are arranged in a matrix on a glass substrate. Their job is to rapidly switch the LCD's pixels on and off. In an LCD Television, each color pixel is created by three sub-pixels with red, green and blue color filters.

One of the biggest challenges for LCD television manufacturers has been speeding up the "pixel response" time (how fast an individual pixel's color can change without blurring) to ensure that fast-moving objects don't exhibit "motion lag" or ghosting. It's especially critical for larger-screen LCD Televisions where much of the viewing will be DVD movies and/or HDTV.

An important difference between plasma and LCD television technology is that an LCD television screen doesn't have a coating of phosphor dots (colors are created through the use of filters). That means you'll never have to worry about image burn-in, which is great news, especially for anyone planning to connect a PC or video game system. LCD televisions are extremely energy-efficient, typically consuming 60% less power than comparably-sized tube-type direct-view TVs.