Audioengine W1 General Specifications
Range:100ft (30 meters) Wireless protocol:802.11 Frequency band:2.4-2.4835GHz Latency:<20mSecSNR:91dB Dimensions:100 x 30 x 10mm (LxWxH)
We transmit uncompressed PCM audio in the very-crowded 2.4GHz range, but use a closed protocol specifically designed for audio. The key features that make AW1 better than most wireless systems currently on the market are the ease of setup, fixed low latency, audio quality, lack of dropouts, and high interference tolerance.
The system used in the AW1 was designed and tested to ensure that interference-free audio quality is preserved while sharing the RF spectrum with other common wireless transmission technologies such as WLAN, Bluetooth, microwave ovens, cordless telephones, and others. The system was tested end-to-end system performance using PEAQ, the latest perceptual quality measurement standard, to ensure the best resulting overall design.
The AW1 incorporates a real-time streaming transmission technology designed specifically for music. It includes 6 quality protection innovations to achieve the most robust audio link in its category:
- Error-tolerant coding that incorporates forward error correction (FEC) coding. FEC ensures that lost bits can be completely reconstructed for common interferers and sources of bit errors. The coding is optimized for lossless performance against common and known interferers. FEC also enables error detection so the system knows when and where data is corrupted. It is analogous to techniques employed on Redbook CDs where the laser head incurs bit-errors as a result of imperfections in the pickup of data from the optical media.
- For larger interferers, AW1 employs sample interleaving and sample error concealment (SEC). This allows AW1 to compensate gradually during periods of increasing signal degradation, thus minimizing audible discontinuities. When encountering interference bursts -- up to 6ms in duration -- SEC can recover every alternate sample, after which the hardware DSP performs linear interpolation to recover lost samples.
- Packet error concealment (PEC) ensures there are no jump discontinuities in the audio stream during periods of severe interference, giving the system time to find a clean channel.
- AW1 employs intelligent, Dynamic Frequency Selection. The system avoids interference by constantly monitoring the entire 2.4 GHz spectrum, choosing the channel that can achieve the cleanest transmission. As conditions on a currently occupied channel deteriorate, the system detects this, and switches channels (in under 20 ms) without any interruption in the audio stream.
- AW1 employs dynamic transmit power control. This means that AW1 is transmitting with only as much power as required to successfully maintain a clear audio connection. This makes AW1 coexist better with other 2.4 GHz devices, including WLAN, BT, and other Audioengine wireless devices.
- AW1 combats RF fading, or multi-path-induced signal-strength fluctuations, by natively supporting antenna diversity. Support for dual antennas allows the system to "navigate" around zones of decreased signal strength by creating four possible antenna-to-antenna paths for the system to choose from on a continual basis. The end-result is an overall improvement in audio signal robustness due to an improved link margin.
AW1 Footprint
The AW1 system divides the band between 2405 MHz and 2477 MHz into 37 discrete, 2 MHz wide channels. Channels numbered 2 through 38 inclusive are used for system operation. The system scans the spectrum and selects two channels that are 18 channels (or 36 mHz) apart and transmits with 50% of the time on one channel (for example channel 2) and 50% on the other channel (for example channel 20). The system stays on theses selected channels until the error detection rate reaches a pre-determined level indicating deteriorating RF conditions. The system will select a cleaner channel for transmission and move there without any drop in audio.
The AW1 system divides the band between 2405 MHz and 2477 MHz into 37 discrete, 2 MHz wide channels. Channels numbered 2 through 38 inclusive are used for system operation. The system scans the spectrum and selects two channels that are 18 channels (or 36 mHz) apart and transmits with 50% of the time on one channel (for example channel 2) and 50% on the other channel (for example channel 20). The system stays on theses selected channels until the error detection rate reaches a pre-determined level indicating deteriorating RF conditions. The system will select a cleaner channel for transmission and move there without any drop in audio.
WLAN Footprint
Wireless LAN networks are utilized throughout the home and office environment, the bulk operating in the 2.4GHz band. Most WLAN systems divide the spectrum into three channels, operate on a fixed channel and occupy 1/3 of the bandwidth. WLAN routers scan the system will only start transmitting if the spectrum is clear. Therefore systems that aim to share the RF space with WLAN routers need to be able to detect and move away from channels that are used by WLAN routers. In addition, systems with a 100% duty cycle on a WLAN channel will block WLAN permanently. The system used in the AW1 was designed to coexist with WLAN and other systems operating in the 2.4GHz environment.
Wireless LAN networks are utilized throughout the home and office environment, the bulk operating in the 2.4GHz band. Most WLAN systems divide the spectrum into three channels, operate on a fixed channel and occupy 1/3 of the bandwidth. WLAN routers scan the system will only start transmitting if the spectrum is clear. Therefore systems that aim to share the RF space with WLAN routers need to be able to detect and move away from channels that are used by WLAN routers. In addition, systems with a 100% duty cycle on a WLAN channel will block WLAN permanently. The system used in the AW1 was designed to coexist with WLAN and other systems operating in the 2.4GHz environment.
AW1 and WLAN
Since the AW1 transmits on a channel only 50% of the time, it gives WLAN the opportunity to enter the spectrum. When a new WLAN connection is detected, AW1 will select a different channel for transmission. Depending on the signal strength and the channel selection, multiple AW1 devices can operate in the vicinity of multiple WLAN networks.
Since the AW1 transmits on a channel only 50% of the time, it gives WLAN the opportunity to enter the spectrum. When a new WLAN connection is detected, AW1 will select a different channel for transmission. Depending on the signal strength and the channel selection, multiple AW1 devices can operate in the vicinity of multiple WLAN networks.
