I will take a look at how modern day sound transmission technologies which are employed in current wireless speakers work in real-world situations with a large amount of interference from other wireless equipment.
The most popular frequency bands which are employed by wireless gizmos include the 900 MHz, 2.4 GHz and 5.8 Gigahertz frequency band. Primarily the 900 MHz and also 2.4 Gigahertz frequency bands have begun to become clogged by the ever increasing amount of products just like wireless speakers, cordless telephones and so forth.
Conventional FM transmitters normally work at 900 MHz and don't have any certain means of dealing with interference yet switching the transmit channel is a strategy to deal with interfering transmitters. Digital audio transmission is usually utilized by newer audio products. Digital transmitters commonly function at 2.4 Gigahertz or 5.8 Gigahertz. The signal bandwidth is higher than 900 MHz transmitters and thus competition in these frequency bands is high. Frequency hopping systems, nonetheless, will continue to lead to further problems because they will disrupt even transmitters employing transmit channels. Thus modern-day audio transmitters use special mechanisms to cope with interfering transmitters to ensure continuous interruption-free sound transmission.
One of these methods is referred to as forward error correction or FEC for short. The transmitter will transmit additional data besides the sound data. The receiver employs a formula that makes use of the additional information. When the signal is damaged during the transmission because of interference, the receiver may filter out the invalid data and recover the original signal. This approach works if the level of interference doesn't exceed a specific threshold. FEC is unidirectional. The receiver doesn't send back any kind of data to the transmitter. Thus it is often employed for equipment such as radio receivers where the number of receivers is big.
Yet another method makes use of bidirectional transmission, i.e. each receiver sends information back to the transmitter. This strategy is only practical if the number of receivers is small. Additionally, it requires a back channel to the transmitter. The data which is broadcast has a checksum. From this checksum the receiver can determine whether any certain packet was received correctly and acknowledge. In cases of dropped packets, the receiver is going to notify the transmitter and the lost packet is resent. As such both the transmitter and also receiver have to have a buffer in order to store packets. Using buffers brings about a delay or latency in the transmission. The amount of the delay is proportional to the buffer size. A larger buffer size increases the stability of the transmission. A large latency can generate problems for certain applications nonetheless. Particularly when video is present, the sound must be in sync with the video. Also, in multichannel surround sound applications where a few speakers are cordless, the wireless loudspeakers should be synchronized with the corded speakers. Devices that integrate this mechanism, nevertheless, are limited to transmitting to a few receivers and the receivers use up more power.
Often a frequency channel can get occupied by a different transmitter. Ideally the transmitter will understand this fact and switch to another channel. To do this, some wireless speakers constantly check which channels are available to enable them to immediately switch to a clear channel. The clean channel is selected from a list of channels that was determined to be clear. A modern technology which utilizes this particular transmission protocol is named adaptive frequency hopping spread spectrum or AFHSS
The most popular frequency bands which are employed by wireless gizmos include the 900 MHz, 2.4 GHz and 5.8 Gigahertz frequency band. Primarily the 900 MHz and also 2.4 Gigahertz frequency bands have begun to become clogged by the ever increasing amount of products just like wireless speakers, cordless telephones and so forth.
Conventional FM transmitters normally work at 900 MHz and don't have any certain means of dealing with interference yet switching the transmit channel is a strategy to deal with interfering transmitters. Digital audio transmission is usually utilized by newer audio products. Digital transmitters commonly function at 2.4 Gigahertz or 5.8 Gigahertz. The signal bandwidth is higher than 900 MHz transmitters and thus competition in these frequency bands is high. Frequency hopping systems, nonetheless, will continue to lead to further problems because they will disrupt even transmitters employing transmit channels. Thus modern-day audio transmitters use special mechanisms to cope with interfering transmitters to ensure continuous interruption-free sound transmission.
One of these methods is referred to as forward error correction or FEC for short. The transmitter will transmit additional data besides the sound data. The receiver employs a formula that makes use of the additional information. When the signal is damaged during the transmission because of interference, the receiver may filter out the invalid data and recover the original signal. This approach works if the level of interference doesn't exceed a specific threshold. FEC is unidirectional. The receiver doesn't send back any kind of data to the transmitter. Thus it is often employed for equipment such as radio receivers where the number of receivers is big.
Yet another method makes use of bidirectional transmission, i.e. each receiver sends information back to the transmitter. This strategy is only practical if the number of receivers is small. Additionally, it requires a back channel to the transmitter. The data which is broadcast has a checksum. From this checksum the receiver can determine whether any certain packet was received correctly and acknowledge. In cases of dropped packets, the receiver is going to notify the transmitter and the lost packet is resent. As such both the transmitter and also receiver have to have a buffer in order to store packets. Using buffers brings about a delay or latency in the transmission. The amount of the delay is proportional to the buffer size. A larger buffer size increases the stability of the transmission. A large latency can generate problems for certain applications nonetheless. Particularly when video is present, the sound must be in sync with the video. Also, in multichannel surround sound applications where a few speakers are cordless, the wireless loudspeakers should be synchronized with the corded speakers. Devices that integrate this mechanism, nevertheless, are limited to transmitting to a few receivers and the receivers use up more power.
Often a frequency channel can get occupied by a different transmitter. Ideally the transmitter will understand this fact and switch to another channel. To do this, some wireless speakers constantly check which channels are available to enable them to immediately switch to a clear channel. The clean channel is selected from a list of channels that was determined to be clear. A modern technology which utilizes this particular transmission protocol is named adaptive frequency hopping spread spectrum or AFHSS
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