Wireless audio is now widely used. A multitude of consumer products for example outdoor speakers are eliminating the cable plus offer greatest freedom of movement. I am going to examine how latest cordless technology can cope with interference from other transmitters and just how well they will work in a real-world situation.
The popularity of wireless gizmos including wireless speakers has caused a rapid rise of transmitters which transmit in the preferred frequency bands of 900 MHz, 2.4 Gigahertz as well as 5.8 GHz and therefore wireless interference has become a serious concern. Conventional FM transmitters typically work at 900 MHz and don’t have any particular means of dealing with interference but switching the transmit channel is a method to deal with interfering transmitters. Digital audio transmission is frequently utilized by newer audio systems. Digital transmitters generally operate at 2.4 GHz or 5.8 GHz. The signal bandwidth is higher than 900 MHz transmitters and thus competition in these frequency bands is high. Simply changing channels, on the other hand, is no reliable remedy for staying away from specific transmitters that use frequency hopping. Frequency hoppers which include Bluetooth systems or many wireless phones will hop through the full frequency spectrum. Thus transmission on channels is going to be disrupted for brief bursts of time. Sound can be considered a real-time protocol. Consequently it has stringent requirements pertaining to stability. Additionally, low latency is essential in lots of applications. Therefore more advanced techniques are necessary to ensure dependability. An often used method is forward error correction where the transmitter transmits extra data with the audio. By using some advanced algorithms, the receiver can then fix the data that may partially be damaged by interfering transmitters. Subsequently, these products may broadcast 100% error-free even when there is interference. Transmitters making use of FEC can broadcast to a multitude of wireless receivers and doesn’t need any feedback from the receiver. In situations in which there’s just a few receivers, commonly another mechanism is employed. The cordless receiver sends data packets to the transmitter to confirm correct receipt of data. The information which is broadcast includes a checksum. Using this checksum the receiver can easily see whether any specific packet was received properly and acknowledge. If a packet was damaged, the receiver is going to alert the transmitter and request retransmission of the packet. As a result, the transmitter needs to store a certain amount of packets in a buffer. Equally, the receiver will have to maintain a data buffer. This is going to introduce an audio latency, also called delay, to the transmission which may be a dilemma for real-time protocols like audio. Commonly, the bigger the buffer is, the larger the robustness of the transmission. A large latency can generate problems for certain applications however. Especially if video is present, the audio tracks should be in sync with the video. In addition, in multichannel applications where several speakers are cordless, the cordless speakers should be synchronized with the corded loudspeakers. One constraint is that products in which the receiver communicates with the transmitter can usually merely transmit to a few cordless receivers. Furthermore, receivers must incorporate a transmitter and usually consume more current
In order to better cope with interference, a few wireless speakers will monitor the available frequency band so as to decide which channels are clear at any moment in time. If any particular channel becomes crowded by a competing transmitter, these devices can change transmission to a clean channel without interruption of the audio. This approach is also referred to as adaptive frequency hopping.
Are Today's Cordless Speakers Reliable Enough? 