A constantly growing quantity of wireless gadgets including bluetooth loudspeakers produces growing competition for the precious frequency space. I’ll evaluate several systems which are employed by modern electronic sound gadgets to determine how well these products may operate in a real-world environment.
The buzz of wireless devices just like wireless speakers is responsible for a rapid rise of transmitters that transmit in the most popular frequency bands of 900 MHz, 2.4 GHz and 5.8 GHz and therefore cordless interference has turned into a significant concern.
The cheapest transmitters normally broadcast at 900 MHz. They operate just like FM radios. Because the FM transmission uses a small bandwidth and thereby just consumes a tiny part of the available frequency space, interference may be eliminated simply by changing to a new channel. Current sound gadgets utilize digital audio transmission and in most cases work at 2.4 Gigahertz. Such digital transmitters broadcast a signal that takes up far more frequency space than 900 MHz transmitters and thus have a greater potential for colliding with other transmitters.
Frequency hopping systems, however, are going to still create problems given that they are going to disrupt even transmitters using transmit channels. Real-time audio has very rigid demands regarding reliability and low latency. In order to provide those, different means are needed.
A frequently employed method is forward error correction in which the transmitter sends extra information with the sound. The receiver employs an algorithm which uses the extra data. In the event the signal is corrupted during the transmission resulting from interference, the receiver may filter out the erroneous information and recover the original signal. This method will work if the level of interference doesn’t go above a certain threshold. Transmitters using FEC may transmit to a huge amount of cordless receivers and does not require any feedback from the receiver. A different approach makes use of receivers which transmit information packets to the transmitter. The information which is broadcast includes a checksum. Because of this checksum the receiver may see whether any certain packet was received properly and acknowledge. If a packet was corrupted, the receiver is going to alert the transmitter and ask for retransmission of the packet. Consequently, the transmitter has to store a certain amount of packets in a buffer. Likewise, the receiver will need to maintain a data buffer. Employing buffers causes a delay or latency in the transmission. The amount of the delay is proportional to the buffer size. A larger buffer size increases the dependability of the transmission. Having said that a large buffer will lead to a large latency which can result in difficulties with speakers not being in sync with the movie. Products which integrate this particular procedure, however, are limited to transmitting to a small number of receivers and the receivers consume more power.
In order to avoid crowded frequency channels, several wireless speakers watch clear channels and may switch to a clean channel when the current channel gets occupied by another transmitter. The clean channel is chosen from a list of channels which has been determined to be clear. One technique which utilizes this particular transmission protocol is called adaptive frequency hopping spread spectrum or AFHSS
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