A constantly increasing number of wireless products for example wireless speakers is causing increasing competition for the precious frequency space. Let me have a look at some systems that are used by current digital audio systems in order to discover how well these systems may operate in a real-world situation. The buzz of cordless devices such as cordless outdoor speakers is mainly responsible for a rapid increase of transmitters that transmit in the most popular frequency bands of 900 MHz, 2.4 GHz as well as 5.8 Gigahertz and thus wireless interference has turned into a serious issue.
FM type audio transmitters are generally the least reliable relating to tolerating interference considering that the transmission doesn’t have any means to cope with competing transmitters. On the other hand, these transmitters use a rather restricted bandwidth and switching channels may often avoid interference. The 2.4 GHz and 5.8 GHz frequency bands are utilized by digital transmitters and also are getting to be very crowded recently given that digital signals occupy a lot more bandwidth than analogue transmitters. Just switching channels, on the other hand, is no reliable remedy for avoiding specific transmitters that use frequency hopping. Frequency hoppers just like Bluetooth products as well as several wireless telephones will hop through the entire frequency spectrum. Hence transmission over channels is going to be disrupted for short bursts of time. Consequently today’s sound transmitters incorporate specific mechanisms to cope with interfering transmitters to ensure consistent interruption-free sound transmission. One approach is named FEC or forward error correction. This approach enables the receiver to repair a damaged signal. For this purpose, additional data is sent by the transmitter. From this additional information, the receiver may restore the original information even if the signal was corrupted to some extent. Transmitters using FEC by itself typically may transmit to any number of cordless receivers. This approach is normally used for systems in which the receiver can’t resend information to the transmitter or in which the quantity of receivers is pretty large, just like digital radios, satellite receivers etc. Yet another technique makes use of bidirectional transmission, i.e. each receiver transmits information back to the transmitter. This method is only helpful if the quantity of receivers is small. In addition, it requires a back channel to the transmitter. The information packets include a checksum from which every receiver can easily see whether a packet was received properly and acknowledge correct receipt to the transmitter. In cases of dropped packets, the receiver is going to notify the transmitter and the dropped packet is resent. Therefore both the transmitter and also receiver have to have a buffer in order to store packets. This will create an audio latency, often called delay, to the transmission which is often a dilemma for real-time protocols such as audio. Typically, the greater the buffer is, the larger the robustness of the transmission. Having said that a large buffer will lead to a large latency which may cause difficulties with speakers not being in sync with the video. One constraint is that products where the receiver communicates with the transmitter can usually merely broadcast to a few wireless receivers. Furthermore, receivers must add a transmitter and usually consume additional current
Often a frequency channel can get occupied by another transmitter. Preferably the transmitter will understand this fact and change to a different channel. To achieve this, a few wireless speakers continually watch which channels are available to enable them to quickly switch to a clear channel. This method is also called adaptive frequency hopping.
Exactly How Do Bluetooth Music Receivers Compare With Bluetooth Loudspeakers? 