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A numerically controlled oscillator (NCO) is a digital signal generator which creates a synchronous (i.e., clocked), discrete-time, discrete-valued representation of a waveform, usually sinusoidal. NCOs are often used in conjunction with a digital-to-analog converter (DAC) at the output to create a direct digital synthesizer (DDS).

Numerically controlled oscillators offer several advantages over other types of oscillators in terms of agility, accuracy, stability and reliability. NCOs are used in many communications systems including digital up/down converters used in 3G wireless and software radio systems, digital phase-locked loops, radar systems, drivers for optical or acoustic transmissions, and multilevel FSK/PSK modulators/demodulators. (Full article...)

The Leslie speaker is a combined amplifier and loudspeaker that projects the signal from an electric or electronic instrument and modifies the sound by rotating a baffle chamber ("drum") in front of the loudspeakers. A similar effect is provided by a rotating system of horns in front of the treble driver. It is most commonly associated with the Hammond organ, though it was later used for the electric guitar and other instruments. A typical Leslie speaker contains an amplifier, a treble horn and a bass speaker—though specific components depend upon the model. A musician controls the Leslie speaker by either an external switch or pedal that alternates between a slow and fast speed setting, known as "chorale" and "tremolo".

The speaker is named after its inventor, Donald Leslie, who began working in the late 1930s to get a speaker for a Hammond organ that better emulated a pipe or theatre organ, and discovered that baffles rotating along the axis of the speaker cone gave the best sound effect. Hammond was not interested in marketing or selling the speakers, so Leslie sold them himself as an add-on, targeting other organs as well as Hammond. Leslie made the first speaker in 1941. The sound of the organ being played through his speaker received national radio exposure across the US, and it became a commercial and critical success. It soon became an essential tool for most jazz organists. In 1965, Leslie sold his business to CBS who, in 1980, sold it to Hammond. Suzuki Musical Instrument Corporation subsequently acquired the Hammond and Leslie brands. (Full article...)

An antimetric electrical network is an electrical network that exhibits anti-symmetrical electrical properties. The term is often encountered in filter theory, but it applies to general electrical network analysis. Antimetric is the diametrical opposite of symmetric; it does not merely mean "asymmetric" (i.e., "lacking symmetry"). It is possible for networks to be symmetric or antimetric in their electrical properties without being physically or topologically symmetric or antimetric. (Full article...)

A composite image filter is an electronic filter consisting of multiple image filter sections of two or more different types.

The image method of filter design determines the properties of filter sections by calculating the properties they would have in an infinite chain of identical sections. In this, the analysis parallels transmission line theory on which it is based. Filters designed by this method are called image parameter filters, or just image filters. An important parameter of image filters is their image impedance, the impedance of an infinite chain of identical sections. (Full article...)

The iPhone 6 and iPhone 6 Plus are smartphones that were designed, developed, and marketed by Apple Inc. They are the eighth generation of the iPhone, succeeding the iPhone 5, iPhone 5c and iPhone 5s, and were announced on September 9, 2014, and released on September 19, 2014. The iPhone 6 and iPhone 6 Plus jointly were themselves replaced as the flagship devices of the iPhone series by the iPhone 6s and iPhone 6s Plus on September 9, 2015. The iPhone 6 and 6 Plus include larger 4.7 and 5.5 inches (120 and 140 mm) displays, a faster processor, upgraded cameras, improved LTE and Wi-Fi connectivity and support for a near-field communications-based mobile payments offering.

The iPhone 6 and 6 Plus received positive reviews, with critics regarding their redesign, specifications, camera, and battery life as being improvements over previous iPhone models. However, aspects of the design of iPhone 6 were also criticized, including plastic strips on the rear of the device for its antenna that disrupted the otherwise metal exterior, and the screen resolution of the standard-sized iPhone 6 being lower than other devices in its class. The iPhone 6 sold extremely well, making it the best-selling iPhone model and the most successful smartphone to date. (Full article...)

m-derived filters or m-type filters are a type of electronic filter designed using the image method. They were invented by Otto Zobel in the early 1920s. This filter type was originally intended for use with telephone multiplexing and was an improvement on the existing constant k type filter. The main problem being addressed was the need to achieve a better match of the filter into the terminating impedances. In general, all filters designed by the image method fail to give an exact match, but the m-type filter is a big improvement with suitable choice of the parameter m. The m-type filter section has a further advantage in that there is a rapid transition from the cut-off frequency of the passband to a pole of attenuation just inside the stopband. Despite these advantages, there is a drawback with m-type filters; at frequencies past the pole of attenuation, the response starts to rise again, and m-types have poor stopband rejection. For this reason, filters designed using m-type sections are often designed as composite filters with a mixture of k-type and m-type sections and different values of m at different points to get the optimum performance from both types. (Full article...)

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Prototype filters are electronic filter designs that are used as a template to produce a modified filter design for a particular application. They are an example of a nondimensionalised design from which the desired filter can be scaled or transformed. They are most often seen in regard to electronic filters and especially linear analogue passive filters. However, in principle, the method can be applied to any kind of linear filter or signal processing, including mechanical, acoustic and optical filters.

Filters are required to operate at many different frequencies, impedances and bandwidths. The utility of a prototype filter comes from the property that all these other filters can be derived from it by applying a scaling factor to the components of the prototype. The filter design need thus only be carried out once in full, with other filters being obtained by simply applying a scaling factor. (Full article...)

Power dividers (also power splitters and, when used in reverse, power combiners) and directional couplers are passive devices used mostly in the field of radio technology. They couple a defined amount of the electromagnetic power in a transmission line to a port enabling the signal to be used in another circuit. An essential feature of directional couplers is that they only couple power flowing in one direction. Power entering the output port is coupled to the isolated port but not to the coupled port. A directional coupler designed to split power equally between two ports is called a hybrid coupler.

Directional couplers are most frequently constructed from two coupled transmission lines set close enough together such that energy passing through one is coupled to the other. This technique is favoured at the microwave frequencies where transmission line designs are commonly used to implement many circuit elements. However, lumped component devices are also possible at lower frequencies, such as the audio frequencies encountered in telephony. Also at microwave frequencies, particularly the higher bands, waveguide designs can be used. Many of these waveguide couplers correspond to one of the conducting transmission line designs, but there are also types that are unique to waveguide. (Full article...)

The Naim NAIT (acronym for "Naim Audio Integrated amplifier") is an integrated amplifier from the British hi-fi manufacturer, Naim Audio. The original NAIT is one of the most recognisable pieces of hi-fi equipment ever made. Hi-fi critic Lucio Cadeddu recognised its legendary status, referring to it as "one of the most controversial and famous integrated amps in the history of HiFi".

Having already made their name producing solid-state pre-amplifier and power-amplifier separates, Naim launched a low-powered integrated amplifier that embodies the qualities of its amplifiers, aimed at cost-conscious audiophiles. (Full article...)

The Yamaha NS-10 is a loudspeaker that became a standard nearfield studio monitor in the music industry among rock and pop recording engineers. Launched in 1978, the NS-10 started life as a bookshelf speaker destined for the domestic environment. It was poorly received but eventually became a valuable tool with which to mix rock recordings. The speaker has a characteristic white-coloured mid–bass drive unit.

Technically, it is known as a speaker that easily reveals poor quality in recordings. Recording engineers sought to dull its treble response by hanging tissue paper in front of it, resulting in what became known as the "tissue paper effect" – a type of comb filtering. The NS-10 has been used to monitor a large number of successful recordings by numerous artists, leading Gizmodo to refer to it as "the most important loudspeaker you never heard of". (Full article...)

Row hammer (also written as rowhammer) is a computer security exploit that takes advantage of an unintended and undesirable side effect in dynamic random-access memory (DRAM) in which memory cells interact electrically between themselves by leaking their charges, possibly changing the contents of nearby memory rows that were not addressed in the original memory access. This circumvention of the isolation between DRAM memory cells results from the high cell density in modern DRAM, and can be triggered by specially crafted memory access patterns that rapidly activate the same memory rows numerous times.

The row hammer effect has been used in some privilege escalation computer security exploits, and network-based attacks are also theoretically possible. (Full article...)

The Linn Isobarik, nicknamed "Bariks" or "Briks", is a loudspeaker designed and manufactured by Linn Products. The Isobarik is known for both its reproduction of low bass frequencies and being very demanding on amplifiers.

Launched in 1973, the Isobarik DMS, Linn's maiden and flagship loudspeaker was based on and named for the isobaric loading principle invented in the 1950s. The speaker exists also as the Isobarik PMS – destined for the professional market. Although discontinued in 1992, it remains popular among audiophiles. (Full article...)

The iPhone 5s is a smartphone that was designed, developed, and marketed by Apple Inc. It is the seventh generation of the iPhone, succeeding the iPhone 5, and unveiled in September 2013, alongside the iPhone 5c.

The iPhone 5s maintained almost the same external design as its predecessor, the iPhone 5, although the 5s received a new white/gold color scheme in addition to white/silver and space gray/black. The 5s has vastly upgraded internal hardware, however. It introduced the A7 64-bit dual-core system-on-chip, the first 64-bit processor to be used on a smartphone, accompanied by the M7 "motion co-processor". A redesigned home button with Touch ID, a fingerprint recognition system which can be used to unlock the phone and authenticate App Store and iTunes Store purchases, was also introduced. The camera was also updated with a larger aperture and a dual-LED flash optimized for different color temperatures. Earphones known as EarPods were included with the 5s, and Apple released accessories including a case and a dock. It had a 4-inch display, similar to the iPhone 5 and iPhone 5c. (Full article...)

The primary line constants are parameters that describe the characteristics of conductive transmission lines, such as pairs of copper wires, in terms of the physical electrical properties of the line. The primary line constants are only relevant to transmission lines and are to be contrasted with the secondary line constants, which can be derived from them, and are more generally applicable. The secondary line constants can be used, for instance, to compare the characteristics of a waveguide to a copper line, whereas the primary constants have no meaning for a waveguide.

The constants are conductor resistance and inductance, and insulator capacitance and conductance, which are by convention given the symbols R, L, C, and G respectively. The constants are enumerated in terms of per unit length. The circuit representation of these elements requires a distributed-element model and consequently calculus must be used to analyse the circuit. The analysis yields a system of two first order, simultaneous linear partial differential equations which may be combined to derive the secondary constants of characteristic impedance and propagation constant. (Full article...)