Misplaced Pages

#914085

44-490: HPF may refer to: High-pass filter High Performance Fortran High-power field , in microscopy Hindustan Photo Films , an Indian film manufacturer Historic Preservation Fund , in the United States Hours post fertilization, a metric for developmental biology Human Proteome Folding Project Hyperpalatable food Hibernation Promoting Factor,

88-406: A filter is a two-port electronic circuit which removes frequency components from a signal (time-varying voltage or current) applied to its input port. A high-pass filter attenuates frequency components below a certain frequency, called its cutoff frequency, allowing higher frequency components to pass through. This contrasts with a low-pass filter , which attenuates frequencies higher than

132-509: A hibernation factor protein Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title HPF . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=HPF&oldid=1236057012 " Category : Disambiguation pages Hidden categories: Short description

176-443: A certain frequency, and a bandpass filter , which allows a certain band of frequencies through and attenuates frequencies both higher and lower than the band. In optics a high pass filter is a transparent or translucent window of colored material that allows light longer than a certain wavelength to pass through and attenuates light of shorter wavelengths. Since light is often measured not by frequency but by wavelength , which

220-420: A cutoff frequency of Because this filter is active , it may have non-unity passband gain. That is, high-frequency signals are inverted and amplified by R 2 / R 1 . All of these first-order high-pass filters are called differentiators , because they perform differentiation for signals whose frequency band is well below the filter's cutoff frequency. Filters of higher order have steeper slope in

264-552: A more detailed treatment of this and the above frequency ranges, see Electromagnetic spectrum . Gravitational waves are also described in Hertz. Current observations are conducted in the 30–7000 Hz range by laser interferometers like LIGO , and the nanohertz (1–1000 nHz) range by pulsar timing arrays . Future space-based detectors are planned to fill in the gap, with LISA operating from 0.1–10 mHz (with some sensitivity from 10 μHz to 100 mHz), and DECIGO in

308-735: A specified frequency range, such as from 20 to 400 Hz on the Midas Heritage 3000, or 20 to 20,000 Hz on the Yamaha M7CL digital mixing console . Veteran systems engineer and live sound mixer Bruce Main recommends that high-pass filters be engaged for most mixer input sources, except for those such as kick drum , bass guitar and piano, sources which will have useful low-frequency sounds. Main writes that DI unit inputs (as opposed to microphone inputs) do not need high-pass filtering as they are not subject to modulation by low-frequency stage wash —low frequency sounds coming from

352-415: A way to determine the output samples in terms of the input samples and the preceding output. The following pseudocode algorithm will simulate the effect of a high-pass filter on a series of digital samples, assuming equally spaced samples: The loop which calculates each of the n {\displaystyle n} outputs can be refactored into the equivalent: However, the earlier form shows how

396-427: Is 1/time (T ). Expressed in base SI units, the unit is the reciprocal second (1/s). In English, "hertz" is also used as the plural form. As an SI unit, Hz can be prefixed ; commonly used multiples are kHz (kilohertz, 10  Hz ), MHz (megahertz, 10  Hz ), GHz (gigahertz, 10  Hz ) and THz (terahertz, 10  Hz ). One hertz (i.e. one per second) simply means "one periodic event occurs per second" (where

440-494: Is also used to describe the clock speeds at which computers and other electronics are driven. The units are sometimes also used as a representation of the energy of a photon , via the Planck relation E  =  hν , where E is the photon's energy, ν is its frequency, and h is the Planck constant . The hertz is defined as one per second for periodic events. The International Committee for Weights and Measures defined

484-467: Is beyond the scope of this article; however, a simple example comes from the conversion of the continuous-time high-pass filter above to a discrete-time realization. That is, the continuous-time behavior can be discretized . From the circuit in Figure 1 above, according to Kirchhoff's Laws and the definition of capacitance : where Q c ( t ) {\displaystyle Q_{c}(t)}

SECTION 10

#1732775371915

528-462: Is different from Wikidata All article disambiguation pages All disambiguation pages High-pass filter In the optical domain filters are often characterised by wavelength rather than frequency. High-pass and low-pass have the opposite meanings, with a "high-pass" filter (more commonly "short-pass") passing only shorter wavelengths (higher frequencies), and vice versa for "low-pass" (more commonly "long-pass"). In electronics,

572-421: Is in ohms , and C is in farads . The filter's frequency response reaches -3dB referenced to the at an infinite frequency at the cutoff frequency. Figure 2 shows an active electronic implementation of a first-order high-pass filter using an operational amplifier . The transfer function of this linear time-invariant system is: In this case, the filter has a passband gain of − R 2 / R 1 and has

616-482: Is inversely related to frequency, a high pass optical filter, which attenuates light frequencies below a cutoff frequency, is often called a short-pass filter; it attenuates longer wavelengths. A resistor and either a capacitor or an inductor can be configured as a first-order high-pass filter. The simple first-order capacitive high-pass filter shown in Figure ;1 is implemented by placing an input voltage across

660-904: Is normally a passive filter that also includes a low-pass filter for the woofer and so often employs both a capacitor and inductor (although very simple high-pass filters for tweeters can consist of a series capacitor and nothing else). As an example, the formula above , applied to a tweeter with a resistance of 10 Ω, will determine the capacitor value for a cut-off frequency of 5 kHz. C = 1 2 π f R = 1 6.28 × 5000 × 10 = 3.18 × 10 − 6 {\displaystyle C={\frac {1}{2\pi fR}}={\frac {1}{6.28\times 5000\times 10}}=3.18\times 10^{-6}} , or approx 3.2 μF. An alternative, which provides good quality sound without inductors (which are prone to parasitic coupling, are expensive, and may have significant internal resistance)

704-441: Is the charge stored in the capacitor at time t {\displaystyle t} . Substituting Equation (Q) into Equation (I) and then Equation (I) into Equation (V) gives: This equation can be discretized. For simplicity, assume that samples of the input and output are taken at evenly spaced points in time separated by Δ T {\displaystyle \Delta _{T}} time. Let

748-493: Is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or cycle ) per second . The hertz is an SI derived unit whose formal expression in terms of SI base units is s , meaning that one hertz is one per second or the reciprocal of one second . It is used only in the case of periodic events. It is named after Heinrich Rudolf Hertz (1857–1894),

792-515: Is to employ bi-amplification with active RC filters or active digital filters with separate power amplifiers for each loudspeaker . Such low-current and low-voltage line level crossovers are called active crossovers . Rumble filters are high-pass filters applied to the removal of unwanted sounds near to the lower end of the audible range or below. For example, noises (e.g., footsteps, or motor noises from record players and tape decks ) may be removed because they are undesired or may overload

836-452: Is usually measured in kilohertz (kHz), megahertz (MHz), or gigahertz (GHz). with the latter known as microwaves . Light is electromagnetic radiation that is even higher in frequency, and has frequencies in the range of tens of terahertz (THz, infrared ) to a few petahertz (PHz, ultraviolet ), with the visible spectrum being 400–790 THz. Electromagnetic radiation with frequencies in the low terahertz range (intermediate between those of

880-477: The R C {\displaystyle RC} time constant equal to the sampling period. If α ≪ 0.5 {\displaystyle \alpha \ll 0.5} , then R C {\displaystyle RC} is significantly smaller than the sampling interval, and R C ≈ α Δ T {\displaystyle RC\approx \alpha \Delta _{T}} . The filter recurrence relation provides

924-463: The RIAA equalization circuit of the preamp . High-pass filters are also used for AC coupling at the inputs of many audio power amplifiers , for preventing the amplification of DC currents which may harm the amplifier, rob the amplifier of headroom, and generate waste heat at the loudspeakers voice coil . One amplifier, the professional audio model DC300 made by Crown International beginning in

SECTION 20

#1732775371915

968-423: The subwoofers or the public address system and wrapping around to the stage. Main indicates that high-pass filters are commonly used for directional microphones which have a proximity effect —a low-frequency boost for very close sources. This low-frequency boost commonly causes problems up to 200 or 300 Hz, but Main notes that he has seen microphones that benefit from a 500 Hz high-pass filter setting on

1012-449: The 0.1–10 Hz range. In computers, most central processing units (CPU) are labeled in terms of their clock rate expressed in megahertz ( MHz ) or gigahertz ( GHz ). This specification refers to the frequency of the CPU's master clock signal . This signal is nominally a square wave , which is an electrical voltage that switches between low and high logic levels at regular intervals. As

1056-561: The 1960s, did not have high-pass filtering at all, and could be used to amplify the DC signal of a common 9-volt battery at the input to supply 18 volts DC in an emergency for mixing console power. However, that model's basic design has been superseded by newer designs such as the Crown Macro-Tech series developed in the late 1980s which included 10 Hz high-pass filtering on the inputs and switchable 35 Hz high-pass filtering on

1100-468: The 1970s. In some usage, the "per second" was omitted, so that "megacycles" (Mc) was used as an abbreviation of "megacycles per second" (that is, megahertz (MHz)). Sound is a traveling longitudinal wave , which is an oscillation of pressure . Humans perceive the frequency of a sound as its pitch . Each musical note corresponds to a particular frequency. An infant's ear is able to perceive frequencies ranging from 20 Hz to 20 000  Hz ;

1144-476: The average adult human can hear sounds between 20 Hz and 16 000  Hz . The range of ultrasound , infrasound and other physical vibrations such as molecular and atomic vibrations extends from a few femtohertz into the terahertz range and beyond. Electromagnetic radiation is often described by its frequency—the number of oscillations of the perpendicular electric and magnetic fields per second—expressed in hertz. Radio frequency radiation

1188-418: The console. High-pass and low-pass filters are also used in digital image processing to perform image modifications, enhancements, noise reduction, etc., using designs done in either the spatial domain or the frequency domain . The unsharp masking , or sharpening, operation used in image editing software is a high-boost filter, a generalization of high-pass. Hertz The hertz (symbol: Hz )

1232-516: The equivalent time constant R C {\displaystyle RC} in terms of the sampling period Δ T {\displaystyle \Delta _{T}} and α {\displaystyle \alpha } : Recalling that then α {\displaystyle \alpha } and f c {\displaystyle f_{c}} are related by: and If α = 0.5 {\displaystyle \alpha =0.5} , then

1276-440: The event being counted may be a complete cycle); 100 Hz means "one hundred periodic events occur per second", and so on. The unit may be applied to any periodic event—for example, a clock might be said to tick at 1 Hz , or a human heart might be said to beat at 1.2 Hz . The occurrence rate of aperiodic or stochastic events is expressed in reciprocal second or inverse second (1/s or s ) in general or, in

1320-403: The first person to provide conclusive proof of the existence of electromagnetic waves . For high frequencies, the unit is commonly expressed in multiples : kilohertz (kHz), megahertz (MHz), gigahertz (GHz), terahertz (THz). Some of the unit's most common uses are in the description of periodic waveforms and musical tones , particularly those used in radio - and audio-related applications. It

1364-449: The hertz has become the primary unit of measurement accepted by the general populace to determine the performance of a CPU, many experts have criticized this approach, which they claim is an easily manipulable benchmark . Some processors use multiple clock cycles to perform a single operation, while others can perform multiple operations in a single cycle. For personal computers, CPU clock speeds have ranged from approximately 1 MHz in

HPF - Misplaced Pages Continue

1408-413: The highest normally usable radio frequencies and long-wave infrared light) is often called terahertz radiation . Even higher frequencies exist, such as that of X-rays and gamma rays , which can be measured in exahertz (EHz). For historical reasons, the frequencies of light and higher frequency electromagnetic radiation are more commonly specified in terms of their wavelengths or photon energies : for

1452-459: The late 1970s ( Atari , Commodore , Apple computers ) to up to 6 GHz in IBM Power microprocessors . Various computer buses , such as the front-side bus connecting the CPU and northbridge , also operate at various frequencies in the megahertz range. Higher frequencies than the International System of Units provides prefixes for are believed to occur naturally in the frequencies of

1496-567: The outputs. Another example is the QSC Audio PLX amplifier series which includes an internal 5 Hz high-pass filter which is applied to the inputs whenever the optional 50 and 30 Hz high-pass filters are turned off. Mixing consoles often include high-pass filtering at each channel strip . Some models have fixed-slope, fixed-frequency high-pass filters at 80 or 100 Hz that can be engaged; other models have sweepable high-pass filters, filters of fixed slope that can be set within

1540-405: The parameter α changes the impact of the prior output y[i-1] and current change in input (x[i] - x[i-1]) . In particular, High-pass filters have many applications. They are used as part of an audio crossover to direct high frequencies to a tweeter while attenuating bass signals which could interfere with, or damage, the speaker. When such a filter is built into a loudspeaker cabinet it

1584-564: The rules for capitalisation of a common noun ; i.e., hertz becomes capitalised at the beginning of a sentence and in titles but is otherwise in lower case. The hertz is named after the German physicist Heinrich Hertz (1857–1894), who made important scientific contributions to the study of electromagnetism . The name was established by the International Electrotechnical Commission (IEC) in 1935. It

1628-426: The same points in time. Making these substitutions: And rearranging terms gives the recurrence relation That is, this discrete-time implementation of a simple continuous-time RC high-pass filter is By definition, 0 ≤ α ≤ 1 {\displaystyle 0\leq \alpha \leq 1} . The expression for parameter α {\displaystyle \alpha } yields

1672-569: The samples of V in {\displaystyle V_{\text{in}}} be represented by the sequence ( x 1 , x 2 , … , x n ) {\displaystyle (x_{1},x_{2},\ldots ,x_{n})} , and let V out {\displaystyle V_{\text{out}}} be represented by the sequence ( y 1 , y 2 , … , y n ) {\displaystyle (y_{1},y_{2},\ldots ,y_{n})} which correspond to

1716-409: The second as "the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium -133 atom" and then adds: "It follows that the hyperfine splitting in the ground state of the caesium 133 atom is exactly 9 192 631 770  hertz , ν hfs Cs = 9 192 631 770  Hz ." The dimension of the unit hertz

1760-407: The series combination of a capacitor and a resistor and using the voltage across the resistor as an output. The transfer function of this linear time-invariant system is: The product of the resistance and capacitance ( R × C ) is the time constant (τ); it is inversely proportional to the cutoff frequency f c , that is, where f c is in hertz , τ is in seconds , R

1804-413: The specific case of radioactivity , in becquerels . Whereas 1 Hz (one per second) specifically refers to one cycle (or periodic event) per second, 1 Bq (also one per second) specifically refers to one radionuclide event per second on average. Even though frequency, angular velocity , angular frequency and radioactivity all have the dimension T , of these only frequency is expressed using

HPF - Misplaced Pages Continue

1848-564: The stopband, such that the slope of n -order filters equals 20n dB per decade. Higher order filters can be achieved simply by cascading these first order filters. While impedance matching and loading must be taken into account when chaining passive filters, active filters can be easily chained because the signal is restored by the output of the op amp at each stage. Various filter topologies and network synthesis filters for higher orders exist, which ease design. Discrete-time high-pass filters can also be designed. Discrete-time filter design

1892-480: The unit hertz. Thus a disc rotating at 60 revolutions per minute (rpm) is said to have an angular velocity of 2 π  rad/s and a frequency of rotation of 1 Hz . The correspondence between a frequency f with the unit hertz and an angular velocity ω with the unit radians per second is The hertz is named after Heinrich Hertz . As with every SI unit named for a person, its symbol starts with an upper case letter (Hz), but when written in full, it follows

1936-490: Was adopted by the General Conference on Weights and Measures (CGPM) ( Conférence générale des poids et mesures ) in 1960, replacing the previous name for the unit, "cycles per second" (cps), along with its related multiples, primarily "kilocycles per second" (kc/s) and "megacycles per second" (Mc/s), and occasionally "kilomegacycles per second" (kMc/s). The term "cycles per second" was largely replaced by "hertz" by

#914085