Misplaced Pages

#479520

39-450: Konami Kukeiha Club ( コナミ矩形波倶楽部 , konami kukeiha kurabu , lit. "Konami Square Wave Club", referring to square waves used in chiptunes in the 1980s) is Konami 's sound team. It is often confused with 矩形波倶楽部 ( Kukeiha Club ), Konami's in-house band that has released albums consisting of their studio performances. They are primarily responsible for the sound and music in the majority of Konami video games. One of their best known works

78-441: A specific range of frequencies . The audible frequency range for humans is typically given as being between about 20 Hz and 20,000 Hz (20 kHz), though the high frequency limit usually reduces with age. Other species have different hearing ranges. For example, some dog breeds can perceive vibrations up to 60,000 Hz. In many media, such as air, the speed of sound is approximately independent of frequency, so

117-399: A circuit or cause a badly positioned threshold to be crossed multiple times.) As already mentioned, an ideal square wave has instantaneous transitions between the high and low levels. In practice, this is never achieved because of physical limitations of the system that generates the waveform. The times taken for the signal to rise from the low level to the high level and back again are called

156-411: A fractional error of Δ f f = 1 2 f T m {\textstyle {\frac {\Delta f}{f}}={\frac {1}{2fT_{\text{m}}}}} where T m {\displaystyle T_{\text{m}}} is the timing interval and f {\displaystyle f} is the measured frequency. This error decreases with frequency, so it

195-478: A heart beats at a frequency of 120 times per minute (2 hertz), the period—the time interval between beats—is half a second (60 seconds divided by 120). For cyclical phenomena such as oscillations , waves , or for examples of simple harmonic motion , the term frequency is defined as the number of cycles or repetitions per unit of time. The conventional symbol for frequency is f or ν (the Greek letter nu )

234-416: A known frequency near the unknown frequency is mixed with the unknown frequency in a nonlinear mixing device such as a diode . This creates a heterodyne or "beat" signal at the difference between the two frequencies. If the two signals are close together in frequency the heterodyne is low enough to be measured by a frequency counter. This process only measures the difference between the unknown frequency and

273-402: A repeating event is accomplished by counting the number of times that event occurs within a specific time period, then dividing the count by the period. For example, if 71 events occur within 15 seconds the frequency is: f = 71 15 s ≈ 4.73 Hz . {\displaystyle f={\frac {71}{15\,{\text{s}}}}\approx 4.73\,{\text{Hz}}.} If

312-403: A system is related to the transition times of the waveform; there are formulas allowing one to be determined approximately from the other. Period (physics) Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals ( sound ), radio waves , and light . For example, if

351-447: A video game musician is a stub . You can help Misplaced Pages by expanding it . This article about a Japanese band or other musical ensemble is a stub . You can help Misplaced Pages by expanding it . Square wave A square wave is a non-sinusoidal periodic waveform in which the amplitude alternates at a steady frequency between fixed minimum and maximum values, with the same duration at minimum and maximum. In an ideal square wave,

390-422: A wide range of harmonics; these can generate electromagnetic radiation or pulses of current that interfere with other nearby circuits, causing noise or errors. To avoid this problem in very sensitive circuits such as precision analog-to-digital converters , sine waves are used instead of square waves as timing references. In musical terms, they are often described as sounding hollow, and are therefore used as

429-413: Is a two-state trajectory . Square waves are universally encountered in digital switching circuits and are naturally generated by binary (two-level) logic devices. They are used as timing references or " clock signals ", because their fast transitions are suitable for triggering synchronous logic circuits at precisely determined intervals. However, as the frequency-domain graph shows, square waves contain

SECTION 10

#1732869162480

468-435: Is also used. The period T is the time taken to complete one cycle of an oscillation or rotation. The frequency and the period are related by the equation f = 1 T . {\displaystyle f={\frac {1}{T}}.} The term temporal frequency is used to emphasise that the frequency is characterised by the number of occurrences of a repeating event per unit time. The SI unit of frequency

507-495: Is called a radio wave . Likewise, an electromagnetic wave with a frequency higher than 8 × 10  Hz will also be invisible to the human eye; such waves are called ultraviolet (UV) radiation. Even higher-frequency waves are called X-rays , and higher still are gamma rays . All of these waves, from the lowest-frequency radio waves to the highest-frequency gamma rays, are fundamentally the same, and they are all called electromagnetic radiation . They all travel through vacuum at

546-411: Is generally a problem at low frequencies where the number of counts N is small. An old method of measuring the frequency of rotating or vibrating objects is to use a stroboscope . This is an intense repetitively flashing light ( strobe light ) whose frequency can be adjusted with a calibrated timing circuit. The strobe light is pointed at the rotating object and the frequency adjusted up and down. When

585-402: Is red light, 800 THz ( 8 × 10  Hz ) is violet light, and between these (in the range 400–800 THz) are all the other colors of the visible spectrum . An electromagnetic wave with a frequency less than 4 × 10  Hz will be invisible to the human eye; such waves are called infrared (IR) radiation. At even lower frequency, the wave is called a microwave , and at still lower frequencies it

624-493: Is termed rotational frequency , is revolution per minute , abbreviated r/min or rpm. 60 rpm is equivalent to one hertz. As a matter of convenience, longer and slower waves, such as ocean surface waves , are more typically described by wave period rather than frequency. Short and fast waves, like audio and radio, are usually described by their frequency. Some commonly used conversions are listed below: For periodic waves in nondispersive media (that is, media in which

663-617: Is the hertz (Hz), named after the German physicist Heinrich Hertz by the International Electrotechnical Commission in 1930. It was adopted by the CGPM (Conférence générale des poids et mesures) in 1960, officially replacing the previous name, cycle per second (cps). The SI unit for the period, as for all measurements of time, is the second . A traditional unit of frequency used with rotating mechanical devices, where it

702-400: Is the speed of light in vacuum, and this expression becomes f = c λ . {\displaystyle f={\frac {c}{\lambda }}.} When monochromatic waves travel from one medium to another, their frequency remains the same—only their wavelength and speed change. Measurement of frequency can be done in the following ways: Calculating the frequency of

741-587: Is the soundtrack to Gensō Suikoden — the majority of the material being composed by member Miki Higashino (Miki-Chan). Motoaki Furukawa (main arranger and guitarist) has been known to perform live with members not part of the in-house band, credited under "Konami Kukeiha Club". For example, disc 1 of the Konami All Stars: The Senryo-Bako Heisei 4 Nen Ban album (KICA-1053~55) is titled "Konami Kukeiha Club Live in Tōkyō." This article about

780-417: The rise time and the fall time respectively. If the system is overdamped , then the waveform may never actually reach the theoretical high and low levels, and if the system is underdamped, it will oscillate about the high and low levels before settling down. In these cases, the rise and fall times are measured between specified intermediate levels, such as 5% and 95%, or 10% and 90%. The bandwidth of

819-503: The floor function directly: x ( t ) = 2 ( 2 ⌊ f t ⌋ − ⌊ 2 f t ⌋ ) + 1 {\displaystyle x(t)=2\left(2\lfloor ft\rfloor -\lfloor 2ft\rfloor \right)+1} and indirectly: x ( t ) = ( − 1 ) ⌊ 2 f t ⌋ . {\displaystyle x(t)=\left(-1\right)^{\lfloor 2ft\rfloor }.} Using

SECTION 20

#1732869162480

858-486: The alternating current in household electrical outlets is 60 Hz (between the tones B ♭ and B; that is, a minor third above the European frequency). The frequency of the ' hum ' in an audio recording can show in which of these general regions the recording was made. Aperiodic frequency is the rate of incidence or occurrence of non- cyclic phenomena, including random processes such as radioactive decay . It

897-512: The basis for wind instrument sounds created using subtractive synthesis . They also make up the "beeping" alerts used in many household, commercial, and industrial contexts. Additionally, the distortion effect used on electric guitars clips the outermost regions of the waveform, causing it to increasingly resemble a square wave as more distortion is applied. Simple two-level Rademacher functions are square waves. The square wave in mathematics has many definitions, which are equivalent except at

936-837: The discontinuities: It can be defined as simply the sign function of a sinusoid: x ( t ) = sgn ⁡ ( sin ⁡ 2 π t T ) = sgn ⁡ ( sin ⁡ 2 π f t ) v ( t ) = sgn ⁡ ( cos ⁡ 2 π t T ) = sgn ⁡ ( cos ⁡ 2 π f t ) , {\displaystyle {\begin{aligned}x(t)&=\operatorname {sgn} \left(\sin {\frac {2\pi t}{T}}\right)=\operatorname {sgn}(\sin 2\pi ft)\\v(t)&=\operatorname {sgn} \left(\cos {\frac {2\pi t}{T}}\right)=\operatorname {sgn}(\cos 2\pi ft),\end{aligned}}} which will be 1 when

975-591: The form 2π(2 k − 1) f ). A curiosity of the convergence of the Fourier series representation of the square wave is the Gibbs phenomenon . Ringing artifacts in non-ideal square waves can be shown to be related to this phenomenon. The Gibbs phenomenon can be prevented by the use of σ-approximation , which uses the Lanczos sigma factors to help the sequence converge more smoothly. An ideal mathematical square wave changes between

1014-1795: The fourier series (below) one can show that the floor function may be written in trigonometric form 2 π arctan ⁡ ( tan ⁡ ( π f t 2 ) ) + 2 π arctan ⁡ ( cot ⁡ ( π f t 2 ) ) {\displaystyle {\frac {2}{\pi }}\arctan \left(\tan \left({\frac {\pi ft}{2}}\right)\right)+{\frac {2}{\pi }}\arctan \left(\cot \left({\frac {\pi ft}{2}}\right)\right)} Using Fourier expansion with cycle frequency f over time t , an ideal square wave with an amplitude of 1 can be represented as an infinite sum of sinusoidal waves: x ( t ) = 4 π ∑ k = 1 ∞ sin ⁡ ( 2 π ( 2 k − 1 ) f t ) 2 k − 1 = 4 π ( sin ⁡ ( ω t ) + 1 3 sin ⁡ ( 3 ω t ) + 1 5 sin ⁡ ( 5 ω t ) + … ) , where  ω = 2 π f . {\displaystyle {\begin{aligned}x(t)&={\frac {4}{\pi }}\sum _{k=1}^{\infty }{\frac {\sin \left(2\pi (2k-1)ft\right)}{2k-1}}\\&={\frac {4}{\pi }}\left(\sin(\omega t)+{\frac {1}{3}}\sin(3\omega t)+{\frac {1}{5}}\sin(5\omega t)+\ldots \right),&{\text{where }}\omega =2\pi f.\end{aligned}}} The ideal square wave contains only components of odd-integer harmonic frequencies (of

1053-421: The frequency of the strobe equals the frequency of the rotating or vibrating object, the object completes one cycle of oscillation and returns to its original position between the flashes of light, so when illuminated by the strobe the object appears stationary. Then the frequency can be read from the calibrated readout on the stroboscope. A downside of this method is that an object rotating at an integer multiple of

1092-455: The high and the low state instantaneously, and without under- or over-shooting. This is impossible to achieve in physical systems, as it would require infinite bandwidth . Square waves in physical systems have only finite bandwidth and often exhibit ringing effects similar to those of the Gibbs phenomenon or ripple effects similar to those of the σ-approximation. For a reasonable approximation to

1131-545: The number of counts is not very large, it is more accurate to measure the time interval for a predetermined number of occurrences, rather than the number of occurrences within a specified time. The latter method introduces a random error into the count of between zero and one count, so on average half a count. This is called gating error and causes an average error in the calculated frequency of Δ f = 1 2 T m {\textstyle \Delta f={\frac {1}{2T_{\text{m}}}}} , or

1170-410: The reference frequency. To convert higher frequencies, several stages of heterodyning can be used. Current research is extending this method to infrared and light frequencies ( optical heterodyne detection ). Visible light is an electromagnetic wave , consisting of oscillating electric and magnetic fields traveling through space. The frequency of the wave determines its color: 400 THz ( 4 × 10 Hz)

1209-560: The rotation rate of a shaft, mechanical vibrations, or sound waves , can be converted to a repetitive electronic signal by transducers and the signal applied to a frequency counter. As of 2018, frequency counters can cover the range up to about 100 GHz. This represents the limit of direct counting methods; frequencies above this must be measured by indirect methods. Above the range of frequency counters, frequencies of electromagnetic signals are often measured indirectly utilizing heterodyning ( frequency conversion ). A reference signal of

Konami Kukeiha Club - Misplaced Pages Continue

1248-414: The same speed (the speed of light), giving them wavelengths inversely proportional to their frequencies. c = f λ , {\displaystyle \displaystyle c=f\lambda ,} where c is the speed of light ( c in vacuum or less in other media), f is the frequency and λ is the wavelength. In dispersive media , such as glass, the speed depends somewhat on frequency, so

1287-1319: The sinusoid is positive, −1 when the sinusoid is negative, and 0 at the discontinuities. Here, T is the period of the square wave and f is its frequency, which are related by the equation f = 1/ T . A square wave can also be defined with respect to the Heaviside step function u ( t ) or the rectangular function Π( t ): x ( t ) = 2 [ ∑ n = − ∞ ∞ Π ( 2 ( t − n T ) T − 1 2 ) ] − 1 = 2 ∑ n = − ∞ ∞ [ u ( t T − n ) − u ( t T − n − 1 2 ) ] − 1. {\displaystyle {\begin{aligned}x(t)&=2\left[\sum _{n=-\infty }^{\infty }\Pi \left({\frac {2(t-nT)}{T}}-{\frac {1}{2}}\right)\right]-1\\&=2\sum _{n=-\infty }^{\infty }\left[u\left({\frac {t}{T}}-n\right)-u\left({\frac {t}{T}}-n-{\frac {1}{2}}\right)\right]-1.\end{aligned}}} A square wave can also be generated using

1326-405: The square-wave shape, at least the fundamental and third harmonic need to be present, with the fifth harmonic being desirable. These bandwidth requirements are important in digital electronics, where finite-bandwidth analog approximations to square-wave-like waveforms are used. (The ringing transients are an important electronic consideration here, as they may go beyond the electrical rating limits of

1365-461: The strobing frequency will also appear stationary. Higher frequencies are usually measured with a frequency counter . This is an electronic instrument which measures the frequency of an applied repetitive electronic signal and displays the result in hertz on a digital display . It uses digital logic to count the number of cycles during a time interval established by a precision quartz time base. Cyclic processes that are not electrical, such as

1404-524: The transitions between minimum and maximum are instantaneous. The square wave is a special case of a pulse wave which allows arbitrary durations at minimum and maximum amplitudes. The ratio of the high period to the total period of a pulse wave is called the duty cycle . A true square wave has a 50% duty cycle (equal high and low periods). Square waves are often encountered in electronics and signal processing , particularly digital electronics and digital signal processing . Its stochastic counterpart

1443-473: The wave speed is independent of frequency), frequency has an inverse relationship to the wavelength , λ ( lambda ). Even in dispersive media, the frequency f of a sinusoidal wave is equal to the phase velocity v of the wave divided by the wavelength λ of the wave: f = v λ . {\displaystyle f={\frac {v}{\lambda }}.} In the special case of electromagnetic waves in vacuum , then v = c , where c

1482-419: The wavelength is not quite inversely proportional to frequency. Sound propagates as mechanical vibration waves of pressure and displacement, in air or other substances. In general, frequency components of a sound determine its "color", its timbre . When speaking about the frequency (in singular) of a sound, it means the property that most determines its pitch . The frequencies an ear can hear are limited to

1521-455: The wavelength of the sound waves (distance between repetitions) is approximately inversely proportional to frequency. In Europe , Africa , Australia , southern South America , most of Asia , and Russia , the frequency of the alternating current in household electrical outlets is 50 Hz (close to the tone G), whereas in North America and northern South America, the frequency of

#479520