Wireless audio is becoming widely used. Many consumer products which include wireless speakers are eliminating the cable plus offer ultimate freedom of movement. I will analyze how latest wireless technology are able to cope with interference from other transmitters and how well they function in a real-world scenario.
FM type audio transmitters usually are the least reliable in regards to tolerating interference considering that the transmission does not have any means to deal with competing transmitters. Nonetheless, these transmitters have a relatively restricted bandwidth and switching channels can frequently steer clear of interference. The 2.4 Gigahertz and 5.8 Gigahertz frequency bands are used by digital transmitters and also have become very congested of late because digital signals occupy a lot more bandwidth as compared to analog transmitters.
A number of cordless systems like Bluetooth devices and also cordless telephones incorporate frequency hopping. Thus merely switching the channel is not going to prevent those frequency hoppers. As a result today's sound transmitters use specific mechanisms to deal with interfering transmitters to assure continuous interruption-free sound transmission.
An often utilized technique is forward error correction where the transmitter sends supplemental data along with the audio. The receiver makes use of an algorithm which utilizes the extra data. In the event the signal is corrupted during the transmission resulting from interference, the receiver may filter out the incorrect information and recover the original signal. This technique will work if the level of interference does not go beyond a certain threshold. Transmitters employing FEC on its own normally can transmit to any amount of cordless receivers. This mechanism is typically used by systems in which the receiver is unable to resend data to the transmitter or in which the number of receivers is rather big, just like digital stereos, satellite receivers etc.
In cases in which there is merely a few receivers, often yet another method is utilized. The wireless receiver will send data packets back to the transmitter to confirm correct receipt of data. The information packets have a checksum from which every receiver can decide if a packet was received correctly and acknowledge proper receipt to the transmitter. Because dropped packets will have to be resent, the transmitter and receivers need to hold data packets in a buffer. This will introduce an audio latency, also referred to as delay, to the transmission which can be an issue for real-time protocols such as audio. Typically, the greater the buffer is, the larger the robustness of the transmission. Video applications, however, require the sound to be in sync with the movie. In such cases a big latency is difficult. Wireless products that use this approach, however, are only able to broadcast to a limited quantity of cordless receivers. Usually the receivers have to be paired to the transmitter. As each receiver also requires transmit functionality, the receivers are more pricey to fabricate and also use up more energy.
Often a frequency channel can become occupied by another transmitter. Preferably the transmitter can recognize this fact and change to a different channel. To accomplish this, several wireless speakers continually monitor which channels are available to enable them to immediately switch to a clean channel. Since the transmitter lists clear channels, there's no delay in looking for a clean channel. It is simply picked from the list. This technique is frequently named adaptive frequency hopping spread spectrum.
FM type audio transmitters usually are the least reliable in regards to tolerating interference considering that the transmission does not have any means to deal with competing transmitters. Nonetheless, these transmitters have a relatively restricted bandwidth and switching channels can frequently steer clear of interference. The 2.4 Gigahertz and 5.8 Gigahertz frequency bands are used by digital transmitters and also have become very congested of late because digital signals occupy a lot more bandwidth as compared to analog transmitters.
A number of cordless systems like Bluetooth devices and also cordless telephones incorporate frequency hopping. Thus merely switching the channel is not going to prevent those frequency hoppers. As a result today's sound transmitters use specific mechanisms to deal with interfering transmitters to assure continuous interruption-free sound transmission.
An often utilized technique is forward error correction where the transmitter sends supplemental data along with the audio. The receiver makes use of an algorithm which utilizes the extra data. In the event the signal is corrupted during the transmission resulting from interference, the receiver may filter out the incorrect information and recover the original signal. This technique will work if the level of interference does not go beyond a certain threshold. Transmitters employing FEC on its own normally can transmit to any amount of cordless receivers. This mechanism is typically used by systems in which the receiver is unable to resend data to the transmitter or in which the number of receivers is rather big, just like digital stereos, satellite receivers etc.
In cases in which there is merely a few receivers, often yet another method is utilized. The wireless receiver will send data packets back to the transmitter to confirm correct receipt of data. The information packets have a checksum from which every receiver can decide if a packet was received correctly and acknowledge proper receipt to the transmitter. Because dropped packets will have to be resent, the transmitter and receivers need to hold data packets in a buffer. This will introduce an audio latency, also referred to as delay, to the transmission which can be an issue for real-time protocols such as audio. Typically, the greater the buffer is, the larger the robustness of the transmission. Video applications, however, require the sound to be in sync with the movie. In such cases a big latency is difficult. Wireless products that use this approach, however, are only able to broadcast to a limited quantity of cordless receivers. Usually the receivers have to be paired to the transmitter. As each receiver also requires transmit functionality, the receivers are more pricey to fabricate and also use up more energy.
Often a frequency channel can become occupied by another transmitter. Preferably the transmitter can recognize this fact and change to a different channel. To accomplish this, several wireless speakers continually monitor which channels are available to enable them to immediately switch to a clean channel. Since the transmitter lists clear channels, there's no delay in looking for a clean channel. It is simply picked from the list. This technique is frequently named adaptive frequency hopping spread spectrum.
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