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Music Without Cable Clutter? - The New Generation Of Wireless Audio Transmitter Devices
Over the years a whole array of wireless audio transmitters have emerged which are supposed to eliminate the cables at home when connecting audio equipment. We will investigate the influence of new technologies on the performance of these products. Moreover, we'll investigate if they keep their promise of eliminating the cable clutter.
AM and FM radio was launched several decades ago and was the first type of wireless audio transmission. FM radio is still popular today. However, newer technologies have begun to replace it. These include DAB broadcasts, satellite and HD radio. Today a variety of consumer devices exist such as wireless microphones, wireless surround sound kits, Bluetooth audio transmitters, baby monitors etc which cut the cord by transmitting audio wirelessly.
One of the main application for wireless audio is distributing music all through the home and setting up loudspeakers without running speaker cords which is a large difficulty in homes that are not wired for audio. The technologies used these days all have pros and cons as we will examine.
One of the most traditional technologies is FM broadcasting. Audio is transmitted via a radio-frequency signal which is modulated (changed in frequency) with an audio signal. The technology, which is called frequency modulation (FM), is fairly straightforward and cost-effective to build and offers high range. As a result, most of today’s 900 MHz wireless headphones use FM transmission. However, FM has some major drawbacks.
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. FM radio waves are often reflected by walls and obstacles. This will cause several components to cancel each other out thus causing a varying signal quality in different locations. This phenomenon is known as multipath fading. Some wireless FM transmitters utilize two antennae in an effort to deal with with this phenomenon (diversity receivers). Another problem is that FM radios easily pick up interference from competing wireless transmitters.
Another technology which has gained popularity lately is known as Bluetooth. Bluetooth was originally designed to connect computer peripheral devices wirelessly. Bluetooth will convert he audio into a digital format. This data is then broadcast via the Bluetooth wireless protocol. One of the advantages is the high robustness against wireless interference. However, Bluetooth was not designed for audio transmissions. As a result is does have several problems. The first drawback is the limited range which typically would be 30 ft or less. The next problem is the fact that Bluetooth does not have sufficient room to transmit CD-quality audio and as a result the audio is compressed first. This compression will result in a loss of audio quality depending on the amount of compression. Another problem is that Bluetooth will introduce a delay or latency to the signal during the broadcast. This delay is a particular drawback for video and surround sound applications. In these applications the sound from the wireless speakers would be out of sync with the video and remaining speakers.
Satellite radio and digital terrestrial radio technologies offer high range but use extensive audio compression leading to degradation of the audio signal and have an audio delay of several seconds.
Another technology transmits the audio signal without compression digitally. This technology is used in wireless audio transmitters from Amphony. By avoiding audio compression, the signal will keep the original quality. This technology offers an audio latency of less than 1 ms. Consequently these transmitters can be used for wireless speaker kits in a home theater setup and other real-time applications.
This technology is rather robust against radio interference from other wireless transmitters by employing a method called forward error correction. The Amphony transmitters operate at 5.8 GHz. This frequency space is less crowded than the 900 MHz or 2.4 GHz bands as a result leading to a further improvement of reliability. In contrast to Bluetooth, any number of wireless receivers can operate from a single wireless audio transmitter which is a concern when sending audio to several rooms within a home.
Digital Terrestrial Receiver (set top box) is locked how to fix?
I edited the channels on my tv thru digital receiver and locked the channels but now I cant get into receiver it has a small blue rectangle with the channel number and below 4 question marks. I am guessing it is asking for a pin. a pin hasnt been used how do I overide or what can I do. Help!!
Try all zeros first as that is usually the default
0 0 0 0
cell-tower-e1264784744610 (ommalik)
LightSquared is fighting for the life of its LTE network as a government
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Multi Digital Terrestrial Receiver with Remote Control DVB-805 from Dinodirect.com
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