Wireless speakers are very similar to traditional loudspeakers that are wired, but they transmit audio signals using radio frequency (RF) waves rather than over audio cables. As things stands today, the term ‘wireless’ in the audio and video world does not mean ‘wireless’ – rather all it means is less wires. And this applies to any wireless speaker system presently. Still, this in itself can turn out to be a great advantage. Home audio systems can be enhanced and made more versatile by incorporating the ability to listen to music from a single source in multiple locations. However, distributing music throughout the homes, theaters, churches, stadiums, arenas, and broadcast facilities has proved to be logistically difficult (Syafiqah, 2010). Home owners could extend the listening range of an audio source by purchasing a multi-room amplifier and having additional wiring installed through-out the house by a professional electrician. However, for many consumers who do not own their homes or who cannot afford such an upgrade, this solution would be impractical. The alternative of having interconnecting wires laid out visibly throughout the home has also been unappealing to most consumers for reasons of safety and aesthetics. Therefore, the lack of an available, affordable technology that would overcome the need for wired audio device interconnection greatly restricted the home audio possibilities for most people. Recently, wireless systems have become available that offer home wide music distribution that is in many cases more practical and more elegant than the wired methods previously mentioned Using wireless communication technology for home entertainment becomes popular.
Wireless speaker system is not a new invention for this century; however, the goal of this project is to improve the size, quality and range of the communication system. Here, wireless speakers are composed of two units: a main speaker unit combining the loudspeaker itself with an RF receiver, and an RF transmitter unit (Syafiqah, 2010). There is normally an amplifier integrated in the speaker’s cabinet because the RF waves alone are not enough to drive the speaker. This integration of amplifier and loudspeaker is known as an active loudspeaker. Manufacturers of these loudspeakers design them to be as lightweight as possible while producing the maximum amount of audio output efficiency. Wireless speakers still need power, so require a nearby AC power outlet, or possibly batteries (DC). Only the wire to the amplifier is eliminated.
The transmitter connects to the audio output of audio devices like speakers. Wireless technology is relatively new for home surround sound systems as well as other systems. There are two types of transmission media for wireless speakers. RF signal based systems, and infrared signal based systems. RF, or radio frequency based systems use radio signals to transmit data, and in this case music, to the remote receiver. RF systems commonly use radio frequencies between 300 MHz and 1000 MHz, with 900 MHz being the most common frequency. Transaction rates range up to 40,000 bits per second (Binti, 2011).
This technology does well for speaker systems that will not have direct LOS (line of sight) from the receiver to the transmitter. Some barriers, such as cement, metal, electronic devices, some plastics, and other materials interrupt or absorb RF signals. The speaker placement can be test by moving speakers around slightly to see where the best reception and audio quality is. This solution is common for outdoor speaker systems, systems that are located in a different room that the audio source, or home wide audio systems. In the location where it would like to place, the speakers is limited to areas of bad coverage, RF repeaters can be purchased to assist transmissions around barriers that are causing transmission problems (Syafiqah, 2010).
These systems are susceptible to radio interference from electronic devices, although new technologies in shielding and spread spectrum solutions are making this less of an issue. RF systems tend to transmit more data, communicate further, are more reliable and are more expensive than the infrared alternative. A transmitter in a wireless network is responsible for generating a high power output signal with adequate signal strength to deliver a sender’s message. Wireless transmitters provide modulated radio waves to carry (transmit) data signals from one place to another that may include a radio frequency (RF) filter system which is used to ensure that the integrity of a sender’s message is not threatened by the many compromising system components that the signal encounters as it progresses through the transmitter.
1.2 System Block Diagram
The system is made up of the transmitter which is incorporated with the microphone; and the receiver unit, the tone control and mixer unit, the audio amplifier unit and the loudspeaker. The block diagram of the system is drawn below
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