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Recently more and more wireless wireless surround sound transmitter products have appeared which claim to bring the ultimate freedom of broadcasting music throughout the home. We will take a look at the most widespread technologies for wireless audio and give some tips for choosing the best wireless audio product.

Getting audio from your living room to your bedroom can be quite a challenge especially in homes which are not wired for audio. The following technologies are used by devices solving this problem: infrared, RF, wireless LAN and powerline.

Infrared wireless audio products are limited to line-of-sight applications, i.e. only operate within a single room because the signal is broadcast as infrared light which can’t go through walls. This technology is often found in wireless speaker kit products.

RF wireless music devices broadcast the audio signal via radio waves. These radio wave signals can without problems go through walls. The signal is broadcast either by utilizing FM transmission or digital transmission. The least expensive choice is FM transmission. Products utilizing FM transmission, on the other hand, have a series of drawbacks. These include degradation of the audio quality due to noise or hiss and audio distortion. In addition, FM transmitter products are also fairly susceptible to interference from other wireless transmitters.

Products utilizing digital wireless audio transmission, such as Amphony audio transmitter products, use a digital protocol in which the audio is converted to a digital signal prior to transmission. Some wireless audio transmitters will employ audio compression, such as Bluetooth transmitters which will decrease the audio quality to some extent. Digital wireless audio transmitters which broadcast the audio uncompressed offer the highest audio fidelity.

Products using wireless LAN are useful when streaming audio from a PC. Their downside is that they normally have some fairly high latency, i.e. the signal will be delayed by some amount since wireless LAN was not particularly designed for real-time audio streaming. Also, some products require to purchase separate wireless LAN modules that are plugged into every audio receiver.

Powerline products send the audio by means of the power mains and provide great range. They run into problems in homes where there are separate mains circuits in terms of being able to cross over into another circuit. Powerline products have another challenge in the form of power surges and spikes which can cause transmission errors. To avoid audio dropouts, these products will commonly have an audio latency of several seconds as a safeguard.

Here are some pointers for choosing the perfect wireless audio system: Try to find a system that can run several wireless receivers from a single transmitter. Ideally an unlimited number of receivers should be supported. That way you don’t need to buy additional transmitters when you start adding receivers in several rooms of your home. Picking a product with some sort of error correction will help mitigate against strong RF interference. Such interference can be caused by other wireless transmitters. Select a digital RF audio transmitter to guarantee that the audio quality is preserved. Make sure the audio delay is less than 10 ms if you have a real-time application such as video.

Make sure the wireless transmitter offers the audio inputs you need. You may need amplified speaker inputs, RCA audio inputs etc. Make sure that you can purchase individual receivers later on as you expand your system. Check that you can get receivers with speaker outputs for connecting regular loudspeakers as well as receivers with line-level RCA outputs. Choose a transmitter that can regulate the audio volume of the input stage. This will give you the flexibility to connect the transmitter to any type of equipment with different signal levels. Otherwise the audio may get clipped inside the transmitter converter stage or the dynamic range is not fully used.

Ensure that the amplified wireless receivers contain built-in digital amplifiers with low distortion figures. This will keep the receiver cool due to high amplifier power efficiency and provide optimum sound quality. Check that the amplified receiver is able to drive speakers with the preferred Ohm rating and that it is small and easily mountable for easy set up. Devices which function in the 5.8 GHz frequency band will have less problems with wireless interference than products utilizing the crowded 900 MHz or 2.4 GHz frequency band.

Are you searching to get a brand new a set of wireless speakers for your home? You may be dazzled by the number of choices you have. To make an informed choice, it is best to familiarize yourself with popular terms. One of these specs is known as “signal-to-noise ratio” and is not often understood. I am going to help explain the meaning of this term.

When you have narrowed down your search by taking a look at some key criteria, like the amount of output power, the size of the loudspeakers as well as the price, you are going to still have quite a few products to choose from. Now it is time to look at some of the technical specs in more detail. Each wireless speaker will create a certain amount of hiss and hum. The signal-to-noise ratio is going to help quantify the level of hiss generated by the speaker.

You can perform a straightforward assessment of the cordless loudspeaker noise by short circuiting the transmitter input, setting the loudspeaker volume to maximum and listening to the speaker. The hiss that you hear is produced by the wireless loudspeaker itself. After that compare different sets of cordless speakers according to the next rule: the smaller the amount of hiss, the higher the noise performance of the cordless loudspeaker. However, keep in mind that you should set all sets of cordless speakers to amplify by the same level to compare several models.

To help you compare the noise performance, cordless loudspeaker makers publish the signal-to-noise ratio in their wireless loudspeaker spec sheets. Simply put, the larger the signal-to-noise ratio, the smaller the amount of noise the wireless speaker generates. There are a number of reasons why cordless loudspeakers are going to add some form of hiss or other unwanted signal. Transistors and resistors that are part of every modern cordless loudspeaker by nature produce noise. Mostly the elements that are located at the input stage of the built-in power amplifier will contribute most to the overall noise. Therefore makers normally will choose low-noise components when designing the cordless speaker amplifier input stage.

The wireless transmission itself also will cause static that is most noticable with models that employ FM transmission at 900 MHz. The amount of hiss is also dependent upon the amount of cordless interference from other transmitters. Modern models are going to normally utilize digital music transmission at 2.4 GHz or 5.8 GHz. The signal-to-noise ratio of digital transmitters is independent from the distance of the cordless loudspeakers. It is determined by how the audio signal is sampled. Furthermore, the quality of parts inside the transmitter will influence the signal-to-noise ratio.

Many modern cordless speakers have built-in power amplifiers that include a power switching stage that switches at a frequency around 500 kHz. Consequently, the output signal of cordless loudspeaker switching amps have a rather large level of switching noise. This noise component, though, is generally inaudible because it is well above 20 kHz. Nonetheless, it may still contribute to speaker distortion. Signal-to-noise ratio is usually only shown within the range of 20 Hz to 20 kHz. Therefore, a lowpass filter is utilized when measuring cordless loudspeaker amps to remove the switching noise.

The signal-to-noise ratio is measured by inputting a 1 kHz test signal 60 dB underneath the full scale and measuring the noise floor of the signal generated by the built-in amp. The volume of the wireless loudspeaker is couple such that the full output wattage of the built-in amplifier can be realized. Next, only the noise in the range of 20 Hz and 20 kHz is considered. The noise at other frequencies is removed by a filter. Subsequently the amount of the noise energy in relation to the full-scale output power is computed and shown in db.

A different convention to state the signal-to-noise ratio makes use of more subjective terms. These terms are “dBA” or “A weighted”. You will discover these terms in many wireless loudspeaker parameter sheets. This method was developed with the knowledge that human hearing perceives noise at different frequencies differently. Human hearing is most sensitive to signals around 1 kHz. On the other hand, signals under 50 Hz and higher than 13 kHz are hardly noticed. An A-weighted signal-to-noise ratio weighs the noise floor according to the human hearing and is usually larger than the unweighted signal-to-noise ratio.

Are you attempting to install a new home theater system or some wireless speakers? The simplest way is to hire a qualified installer to help you. On the other hand, you may contemplate doing the setup yourself. You may think you are technically savvy and that installing your new home theater system is going to be a snap. I will present some suggestions that are going to help you steer clear of various usually made mistakes.

After unpacking your new home theater system, you will normally find a main component and five or 7 loudspeakers. The central element is going to deliver the signal for each and every one of your speakers which you will install. This main component is the main hub of your home theater system. You will normally be able to control it via remote control. It will process the sound and separate it into the sound element for each separate loudspeaker.

Put this receiver in a place which minimizes the loudspeaker cord run to each loudspeaker. If you have your TV up center then a good spot for your receiver may be anywhere near your television set. This is going to also simplify attaching your receiver to the audio output of your TV. However, select an alternate location if your television set already is fairly crowded with different equipment.

It is not too difficult to make the connections between your receiver and TV or DVD player by utilizing a fiberoptical cord. Connecting your satellite loudspeakers takes a little more effort however.

If you have cordless rear speakers you will not need as much speaker cable and the install is going to be somewhat quicker. First of all, calculate how much speaker cord you will need. You will require to keep in mind furnishings and carpets and add some extra length to your calculations. This way you are going to have sufficient cable for all of the twists and turns. If you are planning to drive a lot of output power to your loudspeakers then make sure you pick a cable that is thick enough to handle the current flow. Your subwoofer normally will be an active woofer. This means that it will accept a low-level music signal. You can attach your subwoofer via an RCA cable.

Whilst attaching the loudspeaker cord, make sure that you connect the cord with the correct polarity. Every loudspeaker offers a color-coded terminal, generally red and black. Pick a loudspeaker cable which is color coded to help make sure the correct polarity while connecting to the speaker terminal. In the same way, observe the correct polarity when attaching the speaker cord to your surround receiver in order to keep all of your loudspeakers in phase.

If you are using cordless speakers, there will be a small audio delay incurred throughout the audio transmission to the loudspeakers, also called latency. The amount of latency depends on the wireless system. It is typically less than 25 ms. For best sound, all of the speakers should be in sync. If you have wireless rears then the audio will by slightly out of sync with your other speakers. In order to keep all loudspeakers in sync you are going to need to tweak the receiver to delay the audio going to your wired loudspeakers.

Check the user manual to figure out how to set a delay on particular channels. Home theater systems that were not intended for wireless rear speakers may not come with this ability. In this case you might wish to look for a wireless speaker kit that has very low latency, ideally less than one ms. This is going to keep all of your loudspeakers in perfect sync.

The laws of Physics explain all that goes on around you in the most simple (or as we figure out in college, intensely complicated) method. The laws of Physics are your sharpest tools to build a successful Rube Goldberg Machine. The two that you will need the most are Gravity and Momentum. They will often go hand-in-hand to work against each other, to make your machine carry the connecting elements, or as I call them, the ‘Travelers’, across the machine and towards the final goal. Remember these basic rules:
•Gravity will pull the traveler down, it will build ‘Momentum’, and will then work against ‘Gravity’ itself to climb up. Use this to knock through a barrier or initiate a new traveler, or to help the traveler climb up towards the next part of the machine.
•It may be useful to know that
◦Momentum = Mass × Velocity
◦Potential Energy = Mass × Height of the traveler above the base level × Acceleration due to gravity
◦Kinetic Energy = (Mass × Velocity2 ) ÷ 2.
Use these and a few trial runs to perfect each part and make a Rube Goldberg Machine.

Dissecting a Rube Goldberg Machine

If you will examine each moving mechanism of a Rube Goldberg Machine, you will notice that there are three vital ones – the pulley, the dominoes, and a ball as a traveler. Using the proper counter-weight, the pulley is excellent for pulling your traveler up or gently letting it slide down. For example, a traveler will land in a cup, act as the counter-weight, and pull the new traveler, which is kept in the other cup, upwards. The cup may be positioned such that on reaching the top floor, the cup will tilt and slide the traveler onwards. Dominoes will always be found in a Rube Goldberg Machine. They are difficult to put up, but highly rewarding to be brought down with accuracy. Face it, it’s just fun to watch a length of dominoes collapsing and cascading! Dominoes may be curled around the machine. You can also use pivots or levers so that the last domino that falls from one stack will hit the lever, which will rotate around a pivot and knock down the second stack. The ball is the most widely used traveler you will see, and for very logical reasons. It’s round, moves fast enough to provide good momentum, can move around inside tracks or grooves, and all that. So whenever in doubt, throw a ball in the thing.

While plants and animals both resort to respiration, photosynthesis is only restricted to green plants and few other organisms. This – however, doesn’t mean that the latter is only useful for plants and other organisms which are directly involved. Both these processes are important for all the lifeforms on the planet – either directly or indirectly, as they are related to each other. In order to understand how is photosynthesis related to cellular respiration, one has to get well-versed with the basics of each of them.

Photosynthesis: Photosynthesis is a process wherein synthesis of sugar (glucose) is carried out using sunlight (which acts as the radiant energy), carbon dioxide and water. Simply put, photosynthesis is a chemical process by which plants, algae as well as some species of bacteria produce their own food using sunlight, carbon dioxide and water. When it comes to the chemical equation, photosynthesis is depicted as 6CO2 + 6H2O + Light energy → C6H12O6 + 6O2; wherein carbon dioxide (CO2), water (H2O) and sunlight are reactants and glucose (C6H12O6) and oxygen (O2) are the products of photosynthesis.

Cellular Respiration: In the process of cellular respiration, the biochemical energy derived from nutrients is converted to adenosine triphosphate (ATP), which is necessary for these organisms to facilitate various life functions. Simply put, cellular respiration is a metabolic process wherein the chemical bonds of glucose derived from food are converted to energy which is used by several organisms – including us humans, for various life processes. As far as the cellular respiration chemical equation is concerned, it is depicted as C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy released (2830 kJ mol-1); wherein glucose (C6H12O6) and oxygen (O2) are reactants, whereas carbon dioxide (CO2), water (H2O) and energy are products.

How are Photosynthesis and Cellular Respiration Related? read more »