A Quick Look At How Latest Wireless Speakers Work In Real-World Conditions

An ever growing quantity of cordless systems for example loudspeakers which are cordless is causing increasing competition for the precious frequency space. I’ll check out some systems which are used by current digital audio gadgets in order to see how well these solutions can operate in a real-world environment.

The popularity of cordless gizmos just like wireless speakers has caused a rapid rise of transmitters which broadcast in the most popular frequency bands of 900 MHz, 2.4 Gigahertz and 5.8 GHz and thus wireless interference has turned into a significant issue.

FM type audio transmitters are usually the least robust in regards to tolerating interference considering that the transmission does not have any method to deal with competing transmitters. However, those transmitters possess a rather constrained bandwidth and switching channels may steer clear of interference. The 2.4 GHz and 5.8 GHz frequency bands are utilized by digital transmitters and also are getting to be very crowded recently since digital signals take up a lot more bandwidth compared to analog transmitters.

Quite a few wireless products for instance Bluetooth devices and wireless telephones incorporate frequency hopping. Thus simply switching the channel isn’t going to prevent these kinds of frequency hoppers. Audio can be viewed as a real-time protocol. Therefore it has stringent requirements pertaining to stability. Additionally, low latency is essential in numerous applications. Therefore more innovative techniques are needed to assure dependability.

One of these approaches is known as forward error correction or FEC in short. The transmitter will transmit additional information besides the sound data. Making use of several advanced calculations, the receiver is able to restore the data which may partially be damaged by interfering transmitters. Consequently, these systems can broadcast 100% error-free even when there is interference. Transmitters utilizing FEC alone typically may transmit to any number of cordless receivers. This approach is usually employed for products in which the receiver cannot resend information to the transmitter or where the number of receivers is rather big, like digital stereos, satellite receivers and so on.

One more approach uses receivers that transmit information packets to the transmitter. The information packets include a checksum from which every receiver can determine whether a packet was received properly and acknowledge correct receipt to the transmitter. If a packet was corrupted, the receiver is going to inform the transmitter and ask for retransmission of the packet. Consequently, the transmitter must store a great amount of packets in a buffer. Equally, the receiver must have a data buffer. This buffer causes an audio delay that depends upon the buffer size with a larger buffer improving the robustness of the transmission. Video applications, however, need the sound to be in sync with the video. In this case a large latency is difficult. One constraint is that systems in which the receiver communicates with the transmitter usually can merely broadcast to a few cordless receivers. Furthermore, receivers need to add a transmitter and usually use up additional current

Often a frequency channel may become occupied by another transmitter. Preferably the transmitter is going to understand this fact and switch to another channel. To accomplish this, several wireless speakers continually check which channels are available to enable them to immediately change to a clean channel. This technique is also known as adaptive frequency hopping.

A Brief Comparison Of Stereo Amplifiers

Music amplifiers are at the very heart of every home theater system. As the quality and output power demands of modern loudspeakers increase, so do the demands of audio amps. With the ever growing amount of models and design topologies, such as “tube amplifiers”, “class-A”, “class-D” as well as “t amplifier” types, it is getting more and more demanding to pick the amp that is best for a particular application. This post will describe a few of the most common terms and spell out some of the technical jargon which amp producers regularly employ.

The basic operating principle of an audio amp is rather simple. An audio amp will take a low-level audio signal. This signal regularly originates from a source with a rather high impedance. It subsequently translates this signal into a large-level signal. This large-level signal may also drive speakers with small impedance. To do that, an amp uses one or several elements which are controlled by the low-power signal in order to create a large-power signal. Those elements range from tubes, bipolar transistors to FET transistors.

Tube amps used to be widespread several decades ago. A tube is able to control the current flow according to a control voltage that is connected to the tube. Tubes, however, are nonlinear in their behavior and are going to introduce a quite large amount of higher harmonics or distortion. Though, this characteristic of tube amplifiers still makes these popular. A lot of people describe tube amplifiers as having a warm sound as opposed to the cold sound of solid state amplifiers.

One disadvantage of tube amplifiers is their small power efficiency. In other words, most of the energy consumed by the amplifier is wasted as heat rather than being transformed into audio. For that reason tube amplifiers will run hot and require sufficient cooling. Moreover, tubes are quite costly to build. Therefore tube amplifiers have mostly been replaced by solid-state amps which I will look at next. Solid state amps replace the tube with semiconductor elements, usually bipolar transistors or FETs. The earliest type of solid-state amplifiers is called class-A amplifiers. In class-A amps a transistor controls the current flow according to a small-level signal. A number of amps use a feedback mechanism in order to minimize the harmonic distortion. Regarding harmonic distortion, class-A amplifiers rank highest among all kinds of audio amps. These amplifiers also regularly exhibit very low noise. As such class-A amplifiers are perfect for extremely demanding applications in which low distortion and low noise are crucial. Class-A amps, on the other hand, waste the majority of the energy as heat. For that reason they frequently have big heat sinks and are fairly bulky. By making use of a series of transistors, class-AB amps improve on the low power efficiency of class-A amplifiers. The operating area is divided into two distinct regions. These two areas are handled by separate transistors. Each of these transistors works more efficiently than the single transistor in a class-A amp. As such, class-AB amplifiers are generally smaller than class-A amplifiers. When the signal transitions between the 2 separate regions, however, some level of distortion is being created, thereby class-AB amplifiers will not achieve the same audio fidelity as class-A amps.

In order to further improve the audio efficiency, “class-D” amplifiers utilize a switching stage which is continually switched between 2 states: on or off. None of these 2 states dissipates energy inside the transistor. As a result, class-D amps frequently are able to achieve power efficiencies beyond 90%. The on-off switching times of the transistor are being controlled by a pulse-with modulator (PWM). Usual switching frequencies are in the range of 300 kHz and 1 MHz. This high-frequency switching signal needs to be removed from the amplified signal by a lowpass filter. Commonly a simple first-order lowpass is being used. Both the pulse-width modulator and the transistor have non-linearities that result in class-D amps having bigger audio distortion than other types of amplifiers. More recent mini stereo amps include some sort of mechanism in order to reduce distortion. One approach is to feed back the amplified audio signal to the input of the amplifier to compare with the original signal. The difference signal is subsequently used to correct the switching stage and compensate for the nonlinearity. “Class-T” amplifiers (also referred to as “t-amplifier”) use this type of feedback mechanism and for that reason can be manufactured very small whilst attaining low audio distortion.