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90db Legato Wireless System
By Justin Ong
Category : Sound
Published by Jimmy Tang on Monday, 27th September, 2004
Rating : 3.5 out of 5 stars  

Wireless Legato

Believe it or not, the Legato system isn't a complex gadget at all. The whole deal behind the wireless system that makes it tick is radio wave. Radio wave is in use everywhere, from the debut airing of the latest pop song to that file you're downloading wirelessly into your laptop when you're sipping coffee in a WiFi covered café, radio wave is the answer where a wireless medium is required. When home audio systems start to exceed the stereo twin speaker configuration for multi-channel audio to achieve theatre-like environments, rear surround speakers became a snag instantly. Frankly, it was just a matter of time before someone turns to radio wave again to tackle the cable issue.

Since the Legato uses radio wave, you'll find a transmitter and a receiver unit within the package . On the frequency front, the system is using the same 2.4GHz frequency range as wireless routers and Internet gateways. To prevent it from clashing with these devices, a different radio modulation called GFSK (Gaussian Frequency Shift Keying) was used. Both transmitter and receiver must use the same radio modulation in order for communication to take place. IEEE 802.11b specification uses CCK (Complementary Code Keying) while 802.11g uses both OFDM (Orthogonal Frequency Division Multiplexing) and CCK modulations. Theoretically, chances of conflicts should be extremely low - since the radio modulations in place are very different. For the uninformed, radio modulation is a process of combining carrier frequency and audio signals together. Radio frequency doesn't serve much of a purpose if no information is riding on it and you will hear nothing but static. Simple forms of radio modulation for which you can relate to are AM (Amplitude Modulation) and FM (Frequency Modulation) - now you know what these few characters on your portable radio receiver represent. In actual usage test, the Legato worked flawlessly in a WiFi 802.11b/g environment (Channels 6 and 11 were used) without interfering the network and vice versa.

Zipping back to the real world and practical usages, the Legato wireless system is one that is capable of delivering data rates of up to 5Mbps (or 62.5KB/s). Putting this in digestible context means the bandwidth of the system is more than adequate to transmit an uncompressed audio CD data wirelessly to the receiver unit without sacrificing or losing audio quality.

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