Eliminating the big clutter of cables has lead to a variety of wireless audio transmitter products over the years which promise to untie your home audio equipment. We will take a look at recent products to see whether they can deliver on their promise to eliminate the cable clutter and we'll examine how changing technology has impacted performance of these products.
AM and FM radio was introduced several decades ago and was the first type of wireless audio transmission. While still being popular today, FM radio is now being replaced by new technologies including HD radio, satellite radio and DAB broadcasts. A range of today's wireless consumer products cut the cord such as wireless surround sound kits, baby monitors, wireless microphones and Bluetooth transmitters.
One of the main application for wireless audio is to distribute music throughout the home and setting up speakers without running speaker cables which is a big problem in homes that are not wired for audio. Not every technology is perfect when it comes to wireless audio as we will find out.
Let's look at the most traditional technology first: FM broadcasts. FM audio transmitters send the audio by using a high-frequency signal which is constantly changing in frequency according to the audio signal. The technology, which is called frequency modulation (FM), is fairly simple and cost-effective to build and offers high range. Most of today's wireless consumer devices use FM transmission. FM, however, has serious disadvantages compared with newer technologies.
The first is the fact that the transmission will pick up noise and thus there will be some hiss or static. The amount of noise will actually vary depending on the location of the radio or receiver. This is due to the fact that the radio signal is bouncing off walls and will cancel itself out at different locations. This phenomenon is called multi-path fading. Using two antennae is one method some devices cope with this problem (diversity receivers). Another problem is that FM radios easily pick up interference from competing wireless transmitters.
Bluetooth has gained popularity recently for wireless audio transmission even though this protocol was primarily designed to connect computer peripherals. Bluetooth audio transmitters will convert the audio signal to digital information and then transmit via the Bluetooth protocol. Bluetooth is fairly robust in terms of interference in is well standardized. Bluetooth, however, has some problems in regard to wireless audio since it was not designed for wireless audio originally. The range of the transmission is only 30 ft or less. Also, Bluetooth does not have enough space to send an uncompressed CD-quality audio signal. Therefore the audio is compressed prior to the transmission. As a result of the audio compression, the audio quality will decrease. The final problem is the fact that Bluetooth will introduce a delay in the signal (also called latency) which is a problem when used together with video since the audio will be out of sync or if used in a surround sound setup where some of the speakers would be out of sync with the hard-wired speakers.
Terrestrial digital and satellite radio technologies offer high range but use extensive audio compression and have an audio delay of up to several seconds.
The technology used in Amphony's wireless audio transmitters sends audio in a digital format without audio compression. By avoiding audio compression, the signal will retain 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 setup and other real-time applications.
By using error correction, this technology can cope with interference from competing wireless devices which is key in today's noisy environment. The Amphony transmitters operate at 5.8 GHz. This frequency space is less crowded than the 900 MHz or 2.4 GHz bands thus 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 distributing audio to several rooms within a home.
AM and FM radio was introduced several decades ago and was the first type of wireless audio transmission. While still being popular today, FM radio is now being replaced by new technologies including HD radio, satellite radio and DAB broadcasts. A range of today's wireless consumer products cut the cord such as wireless surround sound kits, baby monitors, wireless microphones and Bluetooth transmitters.
One of the main application for wireless audio is to distribute music throughout the home and setting up speakers without running speaker cables which is a big problem in homes that are not wired for audio. Not every technology is perfect when it comes to wireless audio as we will find out.
Let's look at the most traditional technology first: FM broadcasts. FM audio transmitters send the audio by using a high-frequency signal which is constantly changing in frequency according to the audio signal. The technology, which is called frequency modulation (FM), is fairly simple and cost-effective to build and offers high range. Most of today's wireless consumer devices use FM transmission. FM, however, has serious disadvantages compared with newer technologies.
The first is the fact that the transmission will pick up noise and thus there will be some hiss or static. The amount of noise will actually vary depending on the location of the radio or receiver. This is due to the fact that the radio signal is bouncing off walls and will cancel itself out at different locations. This phenomenon is called multi-path fading. Using two antennae is one method some devices cope with this problem (diversity receivers). Another problem is that FM radios easily pick up interference from competing wireless transmitters.
Bluetooth has gained popularity recently for wireless audio transmission even though this protocol was primarily designed to connect computer peripherals. Bluetooth audio transmitters will convert the audio signal to digital information and then transmit via the Bluetooth protocol. Bluetooth is fairly robust in terms of interference in is well standardized. Bluetooth, however, has some problems in regard to wireless audio since it was not designed for wireless audio originally. The range of the transmission is only 30 ft or less. Also, Bluetooth does not have enough space to send an uncompressed CD-quality audio signal. Therefore the audio is compressed prior to the transmission. As a result of the audio compression, the audio quality will decrease. The final problem is the fact that Bluetooth will introduce a delay in the signal (also called latency) which is a problem when used together with video since the audio will be out of sync or if used in a surround sound setup where some of the speakers would be out of sync with the hard-wired speakers.
Terrestrial digital and satellite radio technologies offer high range but use extensive audio compression and have an audio delay of up to several seconds.
The technology used in Amphony's wireless audio transmitters sends audio in a digital format without audio compression. By avoiding audio compression, the signal will retain 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 setup and other real-time applications.
By using error correction, this technology can cope with interference from competing wireless devices which is key in today's noisy environment. The Amphony transmitters operate at 5.8 GHz. This frequency space is less crowded than the 900 MHz or 2.4 GHz bands thus 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 distributing audio to several rooms within a home.
About the Author:
Gunter Fellbaum has been developing audio and electronic products for over a decade. You can find additional information regarding wireless surround sound kits and other wireless audio products from Amphony's website.
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