A constantly increasing amount of wireless systems which include wireless speakers is bringing about increasing competition for the precious frequency space. Let me have a look at a few systems which are used by current digital sound products in order to see how well these solutions may operate in a real-world situation. The growing interest in cordless consumer gadgets just like wireless speakers has begun to result in difficulties with various devices competing for the limited frequency space. Wireless networks, wireless phones , Bluetooth as well as other products are eating up the valuable frequency space at 900 MHz and 2.4 GHz. Cordless audio gadgets need to guarantee reliable real-time transmission in an environment having a lots of interference.
The most popular frequency bands which might be used 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 started to become crowded by the ever increasing number of devices including wireless speakers, cordless phones etc.
Frequency hopping products, on the other hand, will continue to lead to further problems given that they are going to disrupt even transmitters employing transmit channels. Real-time audio has fairly strict demands concerning reliability and low latency. To be able to provide these, different means are needed.
An often utilized method is forward error correction in which the transmitter transmits extra information combined with the sound. Because of this additional information, the receiver may recover the original data whether or not the signal was corrupted to some degree. FEC is unidirectional. The receiver won't send back any information to the transmitter. As a result it is usually employed for equipment similar to radio receivers where the number of receivers is big.
One more method uses receivers that transmit data packets to the transmitter. The transmitters incorporates a checksum with each data packet. Each receiver can decide if a particular packet was received properly or disrupted due to interference. Subsequently, every cordless receiver will be sending an acknowledgement to the transmitter. If a packet was damaged, the receiver will notify the transmitter and ask for retransmission of the packet. As a result, the transmitter has to store a certain amount of packets in a buffer. Likewise, the receiver must maintain a data buffer. Using buffers will cause 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 stability of the transmission. A big latency can be a problem for many applications nonetheless. Particularly when video exists, the sound should be in sync with the movie. Additionally, in surround applications where a number of loudspeakers are wireless, the wireless speakers ought to be synchronized with the corded speakers. Cordless products that incorporate this method, however, can only broadcast to a restricted number of wireless receivers. Usually the receivers have to be paired to the transmitter. Since each receiver also requires broadcast functionality, the receivers cost more to fabricate and also use up more power.
Often a frequency channel may become occupied by another transmitter. Ideally the transmitter will understand this fact and change to yet another channel. To achieve this, some wireless speakers continuously check which channels are available to enable them to immediately switch to a clean channel. The clear channel is picked out from a list of channels which has been identified to be clean. A modern technology that employs this kind of transmission protocol is referred to as adaptive frequency hopping spread spectrum or AFHSS
The most popular frequency bands which might be used 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 started to become crowded by the ever increasing number of devices including wireless speakers, cordless phones etc.
Frequency hopping products, on the other hand, will continue to lead to further problems given that they are going to disrupt even transmitters employing transmit channels. Real-time audio has fairly strict demands concerning reliability and low latency. To be able to provide these, different means are needed.
An often utilized method is forward error correction in which the transmitter transmits extra information combined with the sound. Because of this additional information, the receiver may recover the original data whether or not the signal was corrupted to some degree. FEC is unidirectional. The receiver won't send back any information to the transmitter. As a result it is usually employed for equipment similar to radio receivers where the number of receivers is big.
One more method uses receivers that transmit data packets to the transmitter. The transmitters incorporates a checksum with each data packet. Each receiver can decide if a particular packet was received properly or disrupted due to interference. Subsequently, every cordless receiver will be sending an acknowledgement to the transmitter. If a packet was damaged, the receiver will notify the transmitter and ask for retransmission of the packet. As a result, the transmitter has to store a certain amount of packets in a buffer. Likewise, the receiver must maintain a data buffer. Using buffers will cause 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 stability of the transmission. A big latency can be a problem for many applications nonetheless. Particularly when video exists, the sound should be in sync with the movie. Additionally, in surround applications where a number of loudspeakers are wireless, the wireless speakers ought to be synchronized with the corded speakers. Cordless products that incorporate this method, however, can only broadcast to a restricted number of wireless receivers. Usually the receivers have to be paired to the transmitter. Since each receiver also requires broadcast functionality, the receivers cost more to fabricate and also use up more power.
Often a frequency channel may become occupied by another transmitter. Ideally the transmitter will understand this fact and change to yet another channel. To achieve this, some wireless speakers continuously check which channels are available to enable them to immediately switch to a clean channel. The clear channel is picked out from a list of channels which has been identified to be clean. A modern technology that employs this kind of transmission protocol is referred to as adaptive frequency hopping spread spectrum or AFHSS
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