Lan Stream
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A Glance At Some Of The Coolest Wireless Audio Gadgets
Recent wireless audio devices such as iPods, wireless headphones and cell phones support new wireless protocols. These protocols are supposed to cut the cord and deliver perfect high-fidelity audio. I will examine if these products keep their promise to provide perfect-quality audio. In addition, I will examine the underlying technologies.
These products fall into 2 categories. The first category of devices already has wireless built in. Second-category products, including a few streaming audio devices, have optional wireless capability. Typically they have a slot to add a wireless LAN card. Newest generation iPods and cell phones already come with built-in WiFi and Bluetooth support.
The Bluetooth protocol is a relatively low-cost solution. However, its drawbacks have an influence on high-quality audio applications and are often overlooked.
1) Limited range
The range of Bluetooth devices is usually only 30 ft. This excludes Bluetooth from multi-room applications.
2) Inadequate data transmission capacity
Bluetooth provides a maximum reliable data rate of around 1 Mbps only. This rate is not high enough to transmit uncompressed CD-quality audio. Consequently Bluetooth wireless devices apply audio compression. The audio will be degraded to some degree because of the audio compression. For this reason higher-end audio equipment usually does not use Bluetooth wireless audio.
3) Audio latency
The signal broadcast via Bluetooth will bear a small delay of at least 10 ms. This is mostly because of the audio compression. While being uncritical for MP3 players, this delay may be a problem for video and other real-time applications.
4) Lacking multi-headphone support
Bluetooth is relatively restricted in terms of supporting streaming to numerous headphones. Streaming to several headphones is helpful for several people wanting to listen to the same transmitter. This is less of a problem for MP3 player applications.
Another widespread protocol is WiFi which supports uncompressed audio but also has drawbacks simultaneously streaming to numerous receivers. As a result of the high availability, WiFi is convenient for streaming audio from a PC. Yet, WiFi products have fairly high power consumption. Because of this wireless headphones generally do not use this technology.
Wireless speakers and wireless amplifier products for home theater speakers typically utilize their own proprietary protocol. Entry-level wireless headphones and speakers generally still utilize FM transmission which offers low cost but is prone to noise and audio degradation.
Newer wireless audio protocols eliminate audio degradation by using digital transmission. These frequently also have mechanisms such as forward error correction to deal with interference from other wireless devices.
Latest-generation wireless amplifiers utilize uncompressed audio transmission. Latest protocols also permit streaming to an infinite number of receivers. This enables whole-house audio distribution.
The audio latency ranges from below 1 ms to up to 20 ms. A small latency is essential for wireless surround sound applications. Wireless audio transmitter products usually operate at 2.4 GHz or sometimes in the less crowded 5.8 GHz frequency band such as Amphony's wireless audio devices.
These wireless amplifiers also differ in regard to amplifier output power, standby power consumption and audio quality. A high-quality audio amplifier is critical for optimal sound quality. Digital amplifiers typically offer a power efficiency of a minimum of 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 fairly high audio distortion. Picking a low-distortion amplifier is essential. Good-quality wireless amplifiers have audio distortion of lower than 0.05%.
Cisco, Telia to activate 'world's fastest internet connection' at 120Gbps, sounds pretty Swede (Engadget)
If the Swedes can dry a load of laundry on a 40Gbps internet connection, just
imagine what they could do with 120Gbps. Melt polar caps? Solve the debt
crisis? Dry _three_ loads of laundry? The possibilities may be limitless, but
we'll all find out soon enough, because Cisco and Telia are aiming to break
the 120Gbps barrier by the end of this weekend. It's all part of this week's
DreamHack, a Swedish digital festival that the Guinness Book recognizes as the
"world's largest LAN party." This year, the two companies will attempt to set
up a 300 kilometer-long connection from Jonkoping to Stockholm, designed to
serve (in theory, anyway) up to 750,000 people at blazing speeds -- of course,
only 20,000 or so will be at DreamHack. The project has been in the works
since last summer, with Telia constructing the fiber network, and Cisco
handling hardware duties with a pair of power-packed CRS-3 routers. The
companies say that the connection, if successful, would set a record for
network "capacity utilization," allowing all 750K users to stream music
simultaneously and to download an entire movie in just .047 seconds. It'll
take us a lot longer ...
VLC media player streaming over a LAN
