An ever increasing number of cordless gadgets such as wireless speakers is bringing about increasing competition for the precious frequency space. Let me check out several technologies which are utilized by current digital audio systems in order to determine how well these products may operate in a real-world environment. The increasing interest in cordless consumer products just like wireless speakers has begun to cause difficulties with numerous gadgets competing for the constrained frequency space. Wireless networks, wireless telephones , Bluetooth and different devices are eating up the valuable frequency space at 900 MHz and 2.4 GHz. Cordless sound gadgets must assure robust real-time transmission within an environment which has a large amount of interference.
The popularity of cordless devices like wireless speakers is responsible for a quick rise of transmitters that transmit in the most popular frequency bands of 900 MHz, 2.4 GHz and 5.8 GHz and thus wireless interference has turned into a serious issue.
Typical FM transmitters normally operate at 900 MHz and do not have any particular way of dealing with interference yet switching the transmit channel is a solution to cope with interfering transmitters. Digital audio transmission is usually employed by more contemporary sound products. Digital transmitters usually function 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.
Just changing channels, nonetheless, is no reliable solution for staying away from specific transmitters which use frequency hopping. Frequency hoppers which include Bluetooth products as well as several cordless telephones are going to hop throughout the entire frequency spectrum. Therefore transmission over channels is going to be disrupted for brief bursts of time. For this reason today's audio transmitters use special mechanisms to deal with interfering transmitters to assure continuous interruption-free sound transmission.
One strategy is named FEC or forward error correction. This approach will allow the receiver to correct a corrupted signal. For this reason, extra information is sent by the transmitter. The receiver uses a formula which uses the extra information. When the signal is damaged during the transmission resulting from interference, the receiver can easily filter out the invalid information and recover the original signal. This method will work if the amount of interference won't exceed a specific limit. FEC is unidirectional. The receiver won't send back any data to the transmitter. Thus it is often employed for products like radio receivers where the number of receivers is large. An additional approach uses bidirectional transmission, i.e. each receiver transmits data to the transmitter. This strategy is only practical if the quantity of receivers is small. In addition, it needs a back channel to the transmitter. The information which is broadcast includes a checksum. Because of this checksum the receiver may see whether any particular packet was received correctly and acknowledge. Considering that lost packets will need to be resent, the transmitter and receivers have to hold data packets in a buffer. Using buffers leads to a delay or latency in the transmission. The amount of the delay is directly related to the buffer size. A bigger buffer size improves the dependability of the transmission. Video applications, however, need the sound to be in sync with the video. In this case a big latency is a problem. One constraint is that systems where the receiver communicates with the transmitter can usually only broadcast to a few wireless receivers. Furthermore, receivers have to incorporate a transmitter and usually use up more current
So as to better deal with interference, several wireless speakers is going to monitor the accessible frequency band as a way to determine which channels are clear at any point in time. If any specific channel gets crowded by a competing transmitter, these systems can switch transmission to a clean channel without interruption of the audio. Considering that the transmitter lists clean channels, there's no delay in looking for a clear channel. It is simply selected from the list. This method is often named adaptive frequency hopping spread spectrum.
The popularity of cordless devices like wireless speakers is responsible for a quick rise of transmitters that transmit in the most popular frequency bands of 900 MHz, 2.4 GHz and 5.8 GHz and thus wireless interference has turned into a serious issue.
Typical FM transmitters normally operate at 900 MHz and do not have any particular way of dealing with interference yet switching the transmit channel is a solution to cope with interfering transmitters. Digital audio transmission is usually employed by more contemporary sound products. Digital transmitters usually function 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.
Just changing channels, nonetheless, is no reliable solution for staying away from specific transmitters which use frequency hopping. Frequency hoppers which include Bluetooth products as well as several cordless telephones are going to hop throughout the entire frequency spectrum. Therefore transmission over channels is going to be disrupted for brief bursts of time. For this reason today's audio transmitters use special mechanisms to deal with interfering transmitters to assure continuous interruption-free sound transmission.
One strategy is named FEC or forward error correction. This approach will allow the receiver to correct a corrupted signal. For this reason, extra information is sent by the transmitter. The receiver uses a formula which uses the extra information. When the signal is damaged during the transmission resulting from interference, the receiver can easily filter out the invalid information and recover the original signal. This method will work if the amount of interference won't exceed a specific limit. FEC is unidirectional. The receiver won't send back any data to the transmitter. Thus it is often employed for products like radio receivers where the number of receivers is large. An additional approach uses bidirectional transmission, i.e. each receiver transmits data to the transmitter. This strategy is only practical if the quantity of receivers is small. In addition, it needs a back channel to the transmitter. The information which is broadcast includes a checksum. Because of this checksum the receiver may see whether any particular packet was received correctly and acknowledge. Considering that lost packets will need to be resent, the transmitter and receivers have to hold data packets in a buffer. Using buffers leads to a delay or latency in the transmission. The amount of the delay is directly related to the buffer size. A bigger buffer size improves the dependability of the transmission. Video applications, however, need the sound to be in sync with the video. In this case a big latency is a problem. One constraint is that systems where the receiver communicates with the transmitter can usually only broadcast to a few wireless receivers. Furthermore, receivers have to incorporate a transmitter and usually use up more current
So as to better deal with interference, several wireless speakers is going to monitor the accessible frequency band as a way to determine which channels are clear at any point in time. If any specific channel gets crowded by a competing transmitter, these systems can switch transmission to a clean channel without interruption of the audio. Considering that the transmitter lists clean channels, there's no delay in looking for a clear channel. It is simply selected from the list. This method is often named adaptive frequency hopping spread spectrum.
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