By Mike Heller
A constantly expanding number of wireless products for instance wireless speakers is bringing about increasing competition for the precious frequency space. I'm going to take a look at some technologies that are utilized by current digital audio gadgets in order to determine how well these products can work in a real-world situation. The most popular frequency bands that are utilized by cordless gizmos are the 900 MHz, 2.4 GHz and 5.8 Gigahertz frequency band. Usually the 900 MHz and also 2.4 GHz frequency bands have begun to become clogged by the increasing quantity of devices like wireless speakers, wireless telephones etc.
FM type sound transmitters are typically the least robust relating to tolerating interference considering that the transmission doesn't have any procedure to cope with competing transmitters. However, those transmitters possess a fairly limited bandwidth and changing channels may often avoid interference. The 2.4 Gigahertz and 5.8 GHz frequency bands are utilized by digital transmitters and also are getting to be rather congested these days since digital signals occupy more bandwidth than analog transmitters.
FM type sound transmitters are typically the least robust relating to tolerating interference considering that the transmission doesn't have any procedure to cope with competing transmitters. However, those transmitters possess a fairly limited bandwidth and changing channels may often avoid interference. The 2.4 Gigahertz and 5.8 GHz frequency bands are utilized by digital transmitters and also are getting to be rather congested these days since digital signals occupy more bandwidth than analog transmitters.
FM type audio transmitters are usually the least reliable when it comes to tolerating interference considering that the transmission doesn't have any procedure to cope with competing transmitters. On the other hand, these transmitters use a fairly constrained bandwidth and switching channels can frequently eliminate interference. Contemporary audio systems employ digital audio transmission and often function at 2.4 GHz. These kinds of digital transmitters send out a signal that takes up more frequency space than 900 MHz transmitters and thus have a greater potential for colliding with other transmitters.
A regularly used strategy is forward error correction where the transmitter transmits additional information combined with the audio. The receiver makes use of an algorithm that uses the additional data. When the signal is corrupted during the transmission due to interference, the receiver can easily remove the invalid information and restore the original signal. This technique will work if the level of interference does not go above a certain threshold. FEC is unidirectional. The receiver will not send back any kind of information to the transmitter. Thus it is usually used by systems like radio receivers in which the quantity of receivers is large.
A different approach uses bidirectional transmission, i.e. each receiver sends data to the transmitter. This strategy is only useful if the quantity of receivers is small. It also needs a back channel to the transmitter. The data packets incorporate a checksum from which each receiver may decide if a packet was received properly and acknowledge proper receipt to the transmitter. In cases of dropped packets, the receiver will alert the transmitter and the lost packet is resent. Therefore both the transmitter and also receiver need a buffer in order to keep packets. Making use of buffers leads to a delay or latency in the transmission. The amount of the delay is proportional to the buffer size. A larger buffer size enhances the dependability of the transmission. Video applications, however, require the sound to be in sync with the movie. In this instance a large latency is difficult. Wireless products that use this approach, nonetheless, can only transmit to a small number of cordless receivers. Normally the receivers have to be paired to the transmitter. Since each receiver also requires broadcast functionality, the receivers are more expensive to make and also consume more energy.
Often a frequency channel can get occupied by a different transmitter. Ideally th
A regularly used strategy is forward error correction where the transmitter transmits additional information combined with the audio. The receiver makes use of an algorithm that uses the additional data. When the signal is corrupted during the transmission due to interference, the receiver can easily remove the invalid information and restore the original signal. This technique will work if the level of interference does not go above a certain threshold. FEC is unidirectional. The receiver will not send back any kind of information to the transmitter. Thus it is usually used by systems like radio receivers in which the quantity of receivers is large.
A different approach uses bidirectional transmission, i.e. each receiver sends data to the transmitter. This strategy is only useful if the quantity of receivers is small. It also needs a back channel to the transmitter. The data packets incorporate a checksum from which each receiver may decide if a packet was received properly and acknowledge proper receipt to the transmitter. In cases of dropped packets, the receiver will alert the transmitter and the lost packet is resent. Therefore both the transmitter and also receiver need a buffer in order to keep packets. Making use of buffers leads to a delay or latency in the transmission. The amount of the delay is proportional to the buffer size. A larger buffer size enhances the dependability of the transmission. Video applications, however, require the sound to be in sync with the movie. In this instance a large latency is difficult. Wireless products that use this approach, nonetheless, can only transmit to a small number of cordless receivers. Normally the receivers have to be paired to the transmitter. Since each receiver also requires broadcast functionality, the receivers are more expensive to make and also consume more energy.
Often a frequency channel can get occupied by a different transmitter. Ideally th
A different approach uses bidirectional transmission, i.e. each receiver sends data to the transmitter. This strategy is only useful if the quantity of receivers is small. It also needs a back channel to the transmitter. The data packets incorporate a checksum from which each receiver may decide if a packet was received properly and acknowledge proper receipt to the transmitter. In cases of dropped packets, the receiver will alert the transmitter and the lost packet is resent. Therefore both the transmitter and also receiver need a buffer in order to keep packets. Making use of buffers leads to a delay or latency in the transmission. The amount of the delay is proportional to the buffer size. A larger buffer size enhances the dependability of the transmission. Video applications, however, require the sound to be in sync with the movie. In this instance a large latency is difficult. Wireless products that use this approach, nonetheless, can only transmit to a small number of cordless receivers. Normally the receivers have to be paired to the transmitter. Since each receiver also requires broadcast functionality, the receivers are more expensive to make and also consume more energy.
Often a frequency channel can get occupied by a different transmitter. Ideally the transmitter is going to recognize this fact and switch to another channel. To do this, a number of wireless speakers consistently watch which channels are available so that they can quickly switch to a clean channel. The clean channel is picked from a list of channels that was identified to be clear. A modern technology that makes use of this particular transmission protocol is named adaptive frequency hopping spread spectrum or AFHSS
About the Author:
Often a frequency channel can get occupied by a different transmitter. Ideally the transmitter is going to recognize this fact and switch to another channel. To do this, a number of wireless speakers consistently watch which channels are available so that they can quickly switch to a clean channel. The clean channel is picked from a list of channels that was identified to be clear. A modern technology that makes use of this particular transmission protocol is named adaptive frequency hopping spread spectrum or AFHSS
About the Author:
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