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Recently a great number of wireless audio products have appeared such as latest-generation wireless headphones, iPods, cell phones and wireless amplifier products that promise to eliminate the cable. I will look at a number of the most recent gizmos and technologies to see how well they operate and in which situations they work best.

A number of products come with wireless already built in while some others, specifically streaming audio products, often have optional wireless ability. Newest generation iPods and mobile phones already come with built-in WiFi and Bluetooth support.

The Bluetooth protocol is a fairly low-cost solution. Yet, its limitations have an effect on high-quality audio applications and are often overlooked.

1) Limited operating range

Bluetooth devices usually just have a 30-foot range which confines Bluetooth to single-room applications.

2) Limited data transmission capacity

Bluetooth will apply audio compression because it does not reliably offer a high-enough data rate for uncompressed audio. Audio compression will degrade the audio quality to some degree. High-quality audio transmission usually does not tolerate this type of degradation. Therefore Bluetooth is typically not used in high-end audio products.

3) Audio delay

Because of audio compression, Bluetooth will cause a signal delay of a minimum of 10 ms which will cause the audio to be to some extent out of sync in case of video and real-time applications. This is yet again less of a setback for MP3 players.

4) No support of multiple headphones

Bluetooth can’t stream to numerous headphones at the same time. This might be a dilemma in cases where several people want to listen to the same Bluetooth transmitter.

Another widespread protocol is WiFi which supports uncompressed audio but also has drawbacks simultaneously streaming to numerous receivers. It is practical for streaming music from a PC because of the high availability but is in general not used in wireless headphone devices as a result of the relatively high power consumption of WiFi.

Wireless speakers and wireless amplifier products for home theater speakers usually use their own proprietary protocol. Entry-level wireless headphones and speakers typically still utilize FM transmission which offers low cost but is prone to noise and audio degradation.

Newer wireless audio protocols avoid audio degradation by employing digital transmission. These frequently also come with mechanisms like forward error correction to cope with interference from other wireless devices.

Newest-generation wireless amplifiers allow streaming to an infinite number of receivers and support uncompressed audio transmission.

The audio latency of these wireless amplifiers is normally between 1 ms and 20 ms. A small-latency amplifier is essential for home theater audio. This ensures that all speakers will be in sync. These wireless audio transmitters normally work at 2.4 GHz. There are also some devices including Amphony’s line of wireless audio devices which work at 5.8 GHz. Products that work at 5.8 GHz have less competition from other wireless products than those utilizing the crowded 2.4 GHz frequency band.

Wireless amplifiers offer different levels of audio quality, output power and standby power. Digital amplifiers usually offer a power efficiency of at least 80% and standby power consumption of less than 5 Watts which keeps them cool during operation and helps save energy. However, some Class-D amps have rather high audio distortion. It is vital to choose a wireless amplifier with low audio distortion. This will make sure good sound quality. High-quality amplifiers have audio distortion of 0.05% or less.

Technorati Tags: wireless amplifier, wireless audio, wireless headphones, wireless surround sound

Online radio such as AOL Radio, Slacker, Pandora and Last.fm have gained attractiveness recently. Moreover, a lot of cordless products such as cell phones support these platforms. Does this indicate the end of conventional radio stations? I will look at the impact of streaming radio on the radio landscape.

I seems that local radio stations are on their way to become extinct. They are being threatened by the advance of online and satellite radio. These competing services typically offer hundreds of music and entertainment channels. Some of the channels are even commercial-free. There is practically an infinite number of online radio stations available.

Pandora in addition to other online radio providers have become available on wireless audio transmitter and portable devices by installing the appropriate app. This raises convenience and mobility of online radio. Mobility has to this point been the largest advantage of local radio.

AOL Radio uses CBS radio as its broadcasting platform. It comes with more than 200 music channels. Additionally it provides access to more than 150 local CBS radio stations. Listeners can also make their own customized radio stations at the CBS radio “play.it” website and save each track for playback on an iPod by utilizing 3-rd party software iGetMusic.

Pandora and other online radio services have in the same way started to offer customized music. The user can enter music-related information such as artist, track or album name. These channels will then select tracks which are similar to the information entered. Other services, on the other hand, fail to offer fully customized music channels.

Are traditional radio stations destined to become extinct by the continuous reduction of market share due to online radio? Online radio has proved useful particularly for niche broadcasters as a result of the inherently lower broadcasting cost in comparison with local radio stations.

Online radio broadcasters have found it hard to be profitable. The major reason is the enormous number of competiting channels which is diluting listeners. At the same time, however, there is less pressure to insert commercials because of the lower costs of broadcasting compared with traditional stations. This has made online radio content more interesting than terrestrial radio.

Local programming such as news and local events, on the other hand, will remain one of the big benefits of local radio. One downside of local radio has been the inferior audio quality of FM broadcasts. On the other hand, that is being remedied by the recent launch of digital radio broadcasts such as HD radio. It is hard to predict a clear winner in the battle between online and local radio as both offer their own unique content and high mobility which are the vital factors that will determine the fate of each service.

Technorati Tags: aol radio, online radio, streaming radio, wireless audio

Setting up multi-channel audio like a home theater system has always been rather complex and manufacturers recently have created unique products and technologies like wireless speaker kit products or virtual surround sound to help simplify this procedure. I will look at several of the latest technologies which were developed to make installing home theater systems a breeze. I will suggests what to look out for when making your buying decision.

Whilst previously setting up a TV has been fairly straightforward, the emergence of multi-channel sound has made setting up home theater systems a great deal more difficult by requiring a number of external speakers to create surround sound. While the traditional 5.1 format needs 6 speakers: a front center, two front side speakers, two rear speaker and a subwoofer, the more modern 7.1 format adds two additional side speakers.

Consequently, home theater installations have become pretty complex. Running wires to remote speakers also is often undesirable due to aesthetic reasons. Vendors have recently launched new devices and technologies. These devices were created to help simplify the installation of home theater kits.

The first solution is called virtual surround sound. This approach will take the audio components which would normally be broadcast by the remote speakers. It then utilizes signal processing to those components and inserts special cues and phase delays. After that these components are mixed with the front speaker sound. The signal processing is designed according to how the human hearing determines the location of a sound. The audio signal is then sent through the front loudspeakers. The signal processing has an effect that will trick the listener into presuming that the sound is originating from a different position.

This technology reduces the quantity of required loudspeakers and avoids long speaker cables but each person will process sound somewhat differently due to the form of the ear. The signal processing is based on measurements which are done using a standard human ear model. If the form of the ear changes, sound will travel differently. Therefore virtual surround will not function equally well for everyone.

One more option for simplifying home theater setups and avoiding long speaker cable runs is to utilize wireless surround sound devices or wireless loudspeakers. A wireless solution will usually include a transmitter component that connects to the TV or source and in addition wireless amplifiers that will be connected to the remote loudspeakers. Customarily the transmitter component will come with amplified loudspeaker inputs and line-level inputs. This offers flexibility to connect to any kind of source. A transmitter volume control helps take full advantage of the dynamic range and eliminates clipping of the sound inside the transmitter.

Whilst a few wireless speaker systems come with a wireless amplifier that connects to two speakers, other devices offer individual wireless amplifiers for every loudspeaker. Entry-level wireless products use FM transmission or audio compression that will degrade the sound quality to some extent. More advanced wireless systems utilize uncompressed digital audio transmission. To make sure that all loudspeakers are in sync in a multi-channel application, be sure that you pick a wireless system which has an audio latency of a few milliseconds at most. A high latency would lead to an echo effect. This effect would degrade the surround effect. Many wireless devices work in the 900 MHz and 2.4 GHz frequency bands. A number of products use the less crowded 5.8 GHz frequency band and consequently have less competition from other wireless gadgets.

Another option are side-reflecting speakers. These systems are also called sound bars. The audio that would normally be sent by the remote loudspeakers is instead broadcast by loudspeakers at the front. These front speakers broadcast the sound at an angle. Then the audio is reflected by the side and rear walls and appears to be originating from besides or behind the viewer. The result heavily is dependent upon the interior, particularly the shape of the room and the decoration. It will function well for square rooms with no obstacles and sound reflecting walls. Then again, realistic scenarios frequently will vary from this ideal and diminish the effect of this approach.

Technorati Tags: wireless amplifier, wireless audio, wireless headphones, wireless surround sound

Online radio such as AOL Radio, Slacker, Pandora and Last.fm have gained attractiveness recently. Moreover, a lot of cordless products such as cell phones support these platforms. Does this indicate the end of conventional radio stations? I will look at the impact of streaming radio on the radio landscape.

I seems that local radio stations are on their way to become extinct. They are being threatened by the advance of online and satellite radio. These competing services typically offer hundreds of music and entertainment channels. Some of the channels are even commercial-free. There is practically an infinite number of online radio stations available.

Pandora in addition to other online radio providers have become available on wireless audio transmitter and portable devices by installing the appropriate app. This raises convenience and mobility of online radio. Mobility has to this point been the largest advantage of local radio.

AOL Radio uses CBS radio as its broadcasting platform. It comes with more than 200 music channels. Additionally it provides access to more than 150 local CBS radio stations. Listeners can also make their own customized radio stations at the CBS radio “play.it” website and save each track for playback on an iPod by utilizing 3-rd party software iGetMusic.

Pandora and other online radio services have in the same way started to offer customized music. The user can enter music-related information such as artist, track or album name. These channels will then select tracks which are similar to the information entered. Other services, on the other hand, fail to offer fully customized music channels.

Are traditional radio stations destined to become extinct by the continuous reduction of market share due to online radio? Online radio has proved useful particularly for niche broadcasters as a result of the inherently lower broadcasting cost in comparison with local radio stations.

Online radio broadcasters have found it hard to be profitable. The major reason is the enormous number of competiting channels which is diluting listeners. At the same time, however, there is less pressure to insert commercials because of the lower costs of broadcasting compared with traditional stations. This has made online radio content more interesting than terrestrial radio.

Local programming such as news and local events, on the other hand, will remain one of the big benefits of local radio. One downside of local radio has been the inferior audio quality of FM broadcasts. On the other hand, that is being remedied by the recent launch of digital radio broadcasts such as HD radio. It is hard to predict a clear winner in the battle between online and local radio as both offer their own unique content and high mobility which are the vital factors that will determine the fate of each service.

Technorati Tags: aol radio, online radio, streaming radio, wireless audio

Recently a great number of wireless audio products have appeared such as latest-generation wireless headphones, iPods, cell phones and wireless amplifier products that promise to eliminate the cable. I will look at a number of the most recent gizmos and technologies to see how well they operate and in which situations they work best.

A number of products come with wireless already built in while some others, specifically streaming audio products, often have optional wireless ability. Newest generation iPods and mobile phones already come with built-in WiFi and Bluetooth support.

The Bluetooth protocol is a fairly low-cost solution. Yet, its limitations have an effect on high-quality audio applications and are often overlooked.

1) Limited operating range

Bluetooth devices usually just have a 30-foot range which confines Bluetooth to single-room applications.

2) Limited data transmission capacity

Bluetooth will apply audio compression because it does not reliably offer a high-enough data rate for uncompressed audio. Audio compression will degrade the audio quality to some degree. High-quality audio transmission usually does not tolerate this type of degradation. Therefore Bluetooth is typically not used in high-end audio products.

3) Audio delay

Because of audio compression, Bluetooth will cause a signal delay of a minimum of 10 ms which will cause the audio to be to some extent out of sync in case of video and real-time applications. This is yet again less of a setback for MP3 players.

4) No support of multiple headphones

Bluetooth can’t stream to numerous headphones at the same time. This might be a dilemma in cases where several people want to listen to the same Bluetooth transmitter.

Another widespread protocol is WiFi which supports uncompressed audio but also has drawbacks simultaneously streaming to numerous receivers. It is practical for streaming music from a PC because of the high availability but is in general not used in wireless headphone devices as a result of the relatively high power consumption of WiFi.

Wireless speakers and wireless amplifier products for home theater speakers usually use their own proprietary protocol. Entry-level wireless headphones and speakers typically still utilize FM transmission which offers low cost but is prone to noise and audio degradation.

Newer wireless audio protocols avoid audio degradation by employing digital transmission. These frequently also come with mechanisms like forward error correction to cope with interference from other wireless devices.

Newest-generation wireless amplifiers allow streaming to an infinite number of receivers and support uncompressed audio transmission.

The audio latency of these wireless amplifiers is normally between 1 ms and 20 ms. A small-latency amplifier is essential for home theater audio. This ensures that all speakers will be in sync. These wireless audio transmitters normally work at 2.4 GHz. There are also some devices including Amphony’s line of wireless audio devices which work at 5.8 GHz. Products that work at 5.8 GHz have less competition from other wireless products than those utilizing the crowded 2.4 GHz frequency band.

Wireless amplifiers offer different levels of audio quality, output power and standby power. Digital amplifiers usually offer a power efficiency of at least 80% and standby power consumption of less than 5 Watts which keeps them cool during operation and helps save energy. However, some Class-D amps have rather high audio distortion. It is vital to choose a wireless amplifier with low audio distortion. This will make sure good sound quality. High-quality amplifiers have audio distortion of 0.05% or less.

Technorati Tags: wireless amplifier, wireless audio, wireless headphones, wireless surround sound

The newest range of wireless audio transmitter devices promises streaming of music throughout the house without limits. We will take a look at various products and technologies to find out in how far these devices are practical for whole-house audio uses and what to look out for when purchasing a wireless system.

Running music in your house can be a intimidating job. Numerous houses are not wired for multi-room audio and getting the music from your living room to your bed room can be quite a problem. There are several technologies solving this problem. These include infrared wireless, RF wireless, wireless LAN (WLAN) and powerline.

Infrared products broadcast the audio as lightwaves. Light cannot go through walls. Consequently devices using infrared, such as wireless surround sound kits, are limited to a single room.

RF wireless products send the music as RF waves – either by utilizing FM transmission or digital transmission – and can therefore without difficulty transmit through walls. FM transmission is inexpensive but quite prone to static, audio distortion and susceptible to interference.

Products utilizing digital wireless audio transmission, such as Amphony audio transmitter products, make use of a digital protocol in which the audio is converted to a digital signal prior to transmission. This method guarantees that the audio quality is fully preserved. Some transmitters utilize some type of audio compression, such as Bluetooth transmitters, which will degrade the audio to some extent. Transmitters which send the audio data uncompressed will attain the maximum fidelity.

WLAN products are convenient for broadcasting audio from a PC. However, wireless LAN was never designed for real-time audio streaming. As a consequence, products using WLAN will introduce some amount of delay to the signal. WLAN receivers often do not have built-in network access. As a result, such products often require buying separate LAN cards. These cards are then plugged into every receiver.

Powerline devices use the power mains to distribute music and provide large range but run into trouble if there are separate mains circuits in the house in terms of crossing between circuits. Another problem confronting powerline products are strong power surges and spikes. Such surges can bring about drpouts in the audio due to errors in the transmission. To safeguard against these errors, powerline products generally build a delay of several seconds into the transmission.

Here are some suggestions for choosing a wireless audio system: If you plan to stream audio into several rooms of your house, be sure to pick a system that permits streaming to multiple receivers at the same time. That way you don’t have to purchase a separate transmitter for every receiver that you are streaming to. Products with some form of error correction will be more immune against radio interference from other wireless transmitters. Digital RF audio transmitters will be able to maintain the original audio quality. If you have time-critical applications where sync of the audio is important then you should get a transmitter with a low audio latency. An audio latency of smaller than 10 ms would be suitable for most scenarios.

Pick a transmitter that has all of the audio inputs you need, e.g. speaker inputs, RCA inputs etc. Choose a system where you can add receivers later on which offer all of the required outputs, e.g. amplified speaker outputs, RCA outputs etc. If you go with a digital audio transmitter, select one with an input audio level control knob to prevent the audio signal from clipping inside the transmitter audio converter. This will ensure optimum dynamic range regardless of the signal level of your equipment.

Check 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 offer maximum sound quality. Select a system that provides receivers that can drive speakers with the preferred Ohm rating. Make sure the receivers have a small form factor and are easily mountable. This will help during the set up. 5.8 GHz wireless devices typically have less problems with interference from other wireless transmitters than products operating at 900 MHz or 2.4 GHz.

Technorati Tags: audio streaming, audio transmitter, wireless audio, wireless surround sound

Over the years a whole array of wireless audio transmitters have emerged which are supposed to cut the cables at home when connecting audio equipment. We will investigate the influence of new technologies on the performance of these devices. In addition, we’ll investigate if they keep their promise of removing the cable clutter.

The first type of wireless audio transmission was in the form of AM and FM radio stations. While still being popular today, FM radio is now being replaced by new technologies such as HD radio, satellite radio and DAB broadcasts. A range of today’s wireless consumer devices cut the cord such as wireless surround sound kits, baby monitors, wireless microphones and Bluetooth transmitters.

One of the main use for wireless audio is distributing music throughout the house and setting up loudspeakers without running speaker cords which is a large problem in houses that are not wired for audio. The technologies used nowadays all have pros and cons as we will examine.

FM transmitters are using the most traditional technology in which audio is sent by altering the frequency of a radio-frequency carrier. This technique is called frequency modulation or FM for short. The biggest advantage of FM transmitters is their simpleness and thus cost as well as range. Most of today’s wireless consumer devices utilize FM transmission. FM, however, has serious disadvantages in comparison with modern technologies.

The FM signal will pick up hiss. Therefore there will be noticeable background noise. The amount of static will depend on the location of the transmitter and radio. This is due to the fact that the radio signal is reflecting off walls and will cancel itself out at different locations. This phenomenon is called multi-path fading. Using two antennae is one approach some devices utilize to cope with this problem (diversity receivers). FM radios will easily pick up interference from other consumer products which is another difficulty.

Bluetooth has gained popularity recently for wireless audio transmission even though this protocol was primarily designed to connect computer peripherals. Bluetooth will convert he audio into a digital format. This data is then sent via the Bluetooth wireless protocol. While offering high robustness against wireless interference, Bluetooth has several problems in regard to audio transmission since it was never designed with the purpose of transmitting audio. Bluetooth merely offers a range of 30 ft or less and will compress the audio since it does not offer enough room to transmit an uncompressed CD-quality signal. As a result of the audio compression, the audio quality will decrease. Bluetooth will cause a delay or latency to the audio signal which is a drawback for surround sound and video applications because the wireless loudspeakers will be out of sync with the remaining loudspeakers and video.

The technologies used for satellite radio and terrestrial digital radio offer high range. However, they also use extensive audio compression. Further, a delay of up to several seconds is introduced.

Another technology transmits the audio signal without compression digitally. This technology is used in wireless audio transmitters from Amphony. By eliminating audio compression, the signal will preserve the original quality. This technology offers an audio latency of less than 1 ms. Therefore these transmitters can be used for wireless speaker kits in a home theater system and other real-time applications.

This technology is quite robust against radio interference from other wireless transmitters by employing a technique called forward error correction. Amphony products use the 5.8 GHz frequency band which is less crowded than the 900 MHz and 2.4 GHz bands. The result is high robustness. Other than Bluetooth, this technology can operate any number of receivers per transmitter which is essential for sending audio to several locations throughout the house.

Technorati Tags: audio transmitter, bluetooth transmitter, wireless audio, wireless audio transmitter

Online radio such as AOL Radio, Slacker, Pandora and Last.fm have gained attractiveness recently. Moreover, a lot of cordless products such as cell phones support these platforms. Does this indicate the end of conventional radio stations? I will look at the impact of streaming radio on the radio landscape.

I seems that local radio stations are on their way to become extinct. They are being threatened by the advance of online and satellite radio. These competing services typically offer hundreds of music and entertainment channels. Some of the channels are even commercial-free. There is practically an infinite number of online radio stations available.

Pandora in addition to other online radio providers have become available on wireless audio transmitter and portable devices by installing the appropriate app. This raises convenience and mobility of online radio. Mobility has to this point been the largest advantage of local radio.

AOL Radio uses CBS radio as its broadcasting platform. It comes with more than 200 music channels. Additionally it provides access to more than 150 local CBS radio stations. Listeners can also make their own customized radio stations at the CBS radio “play.it” website and save each track for playback on an iPod by utilizing 3-rd party software iGetMusic.

Pandora and other online radio services have in the same way started to offer customized music. The user can enter music-related information such as artist, track or album name. These channels will then select tracks which are similar to the information entered. Other services, on the other hand, fail to offer fully customized music channels.

Are traditional radio stations destined to become extinct by the continuous reduction of market share due to online radio? Online radio has proved useful particularly for niche broadcasters as a result of the inherently lower broadcasting cost in comparison with local radio stations.

Online radio broadcasters have found it hard to be profitable. The major reason is the enormous number of competiting channels which is diluting listeners. At the same time, however, there is less pressure to insert commercials because of the lower costs of broadcasting compared with traditional stations. This has made online radio content more interesting than terrestrial radio.

Local programming such as news and local events, on the other hand, will remain one of the big benefits of local radio. One downside of local radio has been the inferior audio quality of FM broadcasts. On the other hand, that is being remedied by the recent launch of digital radio broadcasts such as HD radio. It is hard to predict a clear winner in the battle between online and local radio as both offer their own unique content and high mobility which are the vital factors that will determine the fate of each service.

Technorati Tags: aol radio, online radio, streaming radio, wireless audio

Recently a great number of wireless audio products have appeared such as latest-generation wireless headphones, iPods, cell phones and wireless amplifier products that promise to eliminate the cable. I will look at a number of the most recent gizmos and technologies to see how well they operate and in which situations they work best.

A number of products come with wireless already built in while some others, specifically streaming audio products, often have optional wireless ability. Newest generation iPods and mobile phones already come with built-in WiFi and Bluetooth support.

The Bluetooth protocol is a fairly low-cost solution. Yet, its limitations have an effect on high-quality audio applications and are often overlooked.

1) Limited operating range

Bluetooth devices usually just have a 30-foot range which confines Bluetooth to single-room applications.

2) Limited data transmission capacity

Bluetooth will apply audio compression because it does not reliably offer a high-enough data rate for uncompressed audio. Audio compression will degrade the audio quality to some degree. High-quality audio transmission usually does not tolerate this type of degradation. Therefore Bluetooth is typically not used in high-end audio products.

3) Audio delay

Because of audio compression, Bluetooth will cause a signal delay of a minimum of 10 ms which will cause the audio to be to some extent out of sync in case of video and real-time applications. This is yet again less of a setback for MP3 players.

4) No support of multiple headphones

Bluetooth can’t stream to numerous headphones at the same time. This might be a dilemma in cases where several people want to listen to the same Bluetooth transmitter.

Another widespread protocol is WiFi which supports uncompressed audio but also has drawbacks simultaneously streaming to numerous receivers. It is practical for streaming music from a PC because of the high availability but is in general not used in wireless headphone devices as a result of the relatively high power consumption of WiFi.

Wireless speakers and wireless amplifier products for home theater speakers usually use their own proprietary protocol. Entry-level wireless headphones and speakers typically still utilize FM transmission which offers low cost but is prone to noise and audio degradation.

Newer wireless audio protocols avoid audio degradation by employing digital transmission. These frequently also come with mechanisms like forward error correction to cope with interference from other wireless devices.

Newest-generation wireless amplifiers allow streaming to an infinite number of receivers and support uncompressed audio transmission.

The audio latency of these wireless amplifiers is normally between 1 ms and 20 ms. A small-latency amplifier is essential for home theater audio. This ensures that all speakers will be in sync. These wireless audio transmitters normally work at 2.4 GHz. There are also some devices including Amphony’s line of wireless audio devices which work at 5.8 GHz. Products that work at 5.8 GHz have less competition from other wireless products than those utilizing the crowded 2.4 GHz frequency band.

Wireless amplifiers offer different levels of audio quality, output power and standby power. Digital amplifiers usually offer a power efficiency of at least 80% and standby power consumption of less than 5 Watts which keeps them cool during operation and helps save energy. However, some Class-D amps have rather high audio distortion. It is vital to choose a wireless amplifier with low audio distortion. This will make sure good sound quality. High-quality amplifiers have audio distortion of 0.05% or less.

Technorati Tags: wireless amplifier, wireless audio, wireless headphones, wireless surround sound

Over the years a whole array of wireless audio transmitters have emerged which are supposed to cut the cables at home when connecting audio equipment. We will investigate the influence of new technologies on the performance of these devices. In addition, we’ll investigate if they keep their promise of removing the cable clutter.

The first type of wireless audio transmission was in the form of AM and FM radio stations. While still being popular today, FM radio is now being replaced by new technologies such as HD radio, satellite radio and DAB broadcasts. A range of today’s wireless consumer devices cut the cord such as wireless surround sound kits, baby monitors, wireless microphones and Bluetooth transmitters.

One of the main use for wireless audio is distributing music throughout the house and setting up loudspeakers without running speaker cords which is a large problem in houses that are not wired for audio. The technologies used nowadays all have pros and cons as we will examine.

FM transmitters are using the most traditional technology in which audio is sent by altering the frequency of a radio-frequency carrier. This technique is called frequency modulation or FM for short. The biggest advantage of FM transmitters is their simpleness and thus cost as well as range. Most of today’s wireless consumer devices utilize FM transmission. FM, however, has serious disadvantages in comparison with modern technologies.

The FM signal will pick up hiss. Therefore there will be noticeable background noise. The amount of static will depend on the location of the transmitter and radio. This is due to the fact that the radio signal is reflecting off walls and will cancel itself out at different locations. This phenomenon is called multi-path fading. Using two antennae is one approach some devices utilize to cope with this problem (diversity receivers). FM radios will easily pick up interference from other consumer products which is another difficulty.

Bluetooth has gained popularity recently for wireless audio transmission even though this protocol was primarily designed to connect computer peripherals. Bluetooth will convert he audio into a digital format. This data is then sent via the Bluetooth wireless protocol. While offering high robustness against wireless interference, Bluetooth has several problems in regard to audio transmission since it was never designed with the purpose of transmitting audio. Bluetooth merely offers a range of 30 ft or less and will compress the audio since it does not offer enough room to transmit an uncompressed CD-quality signal. As a result of the audio compression, the audio quality will decrease. Bluetooth will cause a delay or latency to the audio signal which is a drawback for surround sound and video applications because the wireless loudspeakers will be out of sync with the remaining loudspeakers and video.

The technologies used for satellite radio and terrestrial digital radio offer high range. However, they also use extensive audio compression. Further, a delay of up to several seconds is introduced.

Another technology transmits the audio signal without compression digitally. This technology is used in wireless audio transmitters from Amphony. By eliminating audio compression, the signal will preserve the original quality. This technology offers an audio latency of less than 1 ms. Therefore these transmitters can be used for wireless speaker kits in a home theater system and other real-time applications.

This technology is quite robust against radio interference from other wireless transmitters by employing a technique called forward error correction. Amphony products use the 5.8 GHz frequency band which is less crowded than the 900 MHz and 2.4 GHz bands. The result is high robustness. Other than Bluetooth, this technology can operate any number of receivers per transmitter which is essential for sending audio to several locations throughout the house.

Technorati Tags: audio transmitter, bluetooth transmitter, wireless audio, wireless audio transmitter