In this, some base signal ( e. g., a sinusoidal carrier wave ) has one of its properties modulated: amplitude modulation involves altering the amplitude of a sinusoidal voltage waveform by the source information, frequency modulation changes the frequency.

The lowest possible energy an electron can take is therefore analogous to the fundamental frequency of a wave on a string.

it was noted by Bohr that the existence of any sort of wave packet implies uncertainty in the wave frequency and wavelength, since a spread of frequencies is needed to create the packet itself.

But if set to a frequency outside the human audible range then the ear can't perceive the square wave, only the difference between the speaker being switched on and off.

Each partial is a sine wave of different frequency and amplitude that swells and decays over time.

At this point the IF signal consists of a video carrier wave at one frequency and the sound carrier at a fixed offset.

In radio communications, for example, bandwidth is the frequency range occupied by a modulated carrier wave, whereas in optics it is the width of an individual spectral line or the entire spectral range.

The Hankel functions are used to express outward-and inward-propagating cylindrical wave solutions of the cylindrical wave equation, respectively ( or vice versa, depending on the sign convention for the frequency ).

In this work, Doppler postulated his principle ( later coined the Doppler effect ) that the observed frequency of a wave depends on the relative speed of the source and the observer, and he tried to use this concept for explaining the colour of binary stars.

The diode ( originally a crystal diode ) rectifies the AM radio frequency signal, leaving only the positive peaks of the carrier wave.

* The dependence of wave velocity on frequency or wavelength:

The wave that emerges from a point source has amplitude at location r that is given by the solution of the frequency domain wave equation for a point source ( The Helmholtz Equation ),

This is sometimes referred to as spectral coherence, as it is related to the presence of different frequency components in the wave.

The Doppler effect ( or Doppler shift ), named after the Austrian physicist Christian Doppler, who proposed it in 1842 in Prague, is the change in frequency of a wave ( or other periodic event ) for an observer moving relative to its source.

Therefore the time between the arrival of successive wave crests at the observer is reduced, causing an increase in the frequency.

Conversely, if the source of waves is moving away from the observer, each wave is emitted from a position farther from the observer than the previous wave, so the arrival time between successive waves is increased, reducing the frequency.

During World War II and through the 1950s, high frequency (" short wave ") radio was widely used for military and diplomatic communication, and could be intercepted at great distances.

EMR is classified according to the frequency of its wave.

By this standard, it is determined that where two stations operating on the same frequency are involved, objectionable interference from station A exists at any point within the service area of station B where station A's signal is of an intensity one-twentieth or more of the strength of station B's signal at that point.

The effect of the recording is very open and natural, with the frequency emphasis exactly what you would expect from a live performance.

The frequency used for these experiments is 15 mc. and the transducer is a specially cut crystal with an epoxy lens capable of providing beam diameters smaller than one millimeter.

On the other hand, the temporary reduction in hypothalamic excitability through the injection of a barbiturate into the posterior hypothalamus causes a lessening in frequency and amplitude of cortical strychnine spikes until the hypothalamic excitability is restored.

In addition, the cutoff frequency for input accelerations is approximately proportional to the servo loop gain ; ;

The effect is that the platform returns from an off-level position at a rapid rate until it is nearly level, at which point the platform is controlled by a proportional servo with low enough frequency response so that the noise has little effect on the leveling process.

`` However, evidence that the Axis powers are making significant preparations indicative of such an intention is being reported with increasing frequency from a variety of sources.

We know that the number of radio and television impulses, sound waves, ultra-violet rays, etc., that may occupy the very same space, each solitary upon its own frequency, is infinite.

It is she who decides the time, the place, the surroundings, and the frequency of the sexual act.

The participating institutions each broadcast, in real time, a frequency signal with time codes, which is their estimate of TAI.

People tend to be less cooperative if they perceive that the frequency of helpers in the population is lower.

the relative frequency at bin and is the total area of the histogram.

Contrast this with frequency modulation, in which the frequency is varied, and phase modulation, in which the phase is varied.

The Spectrogram produced by such an instrument is a graphical display of the time varying pressure level and frequency profiles which give a specific acoustic signal its defining character.

An equivalent definition is the radius of an unperturbed circular Newtonian orbit about the Sun of a particle having infinitesimal mass, moving with an angular frequency of radians per day ; or that length such that, when used to describe the positions of the objects in the Solar System, the heliocentric gravitational constant ( the product GM < sub >☉</ sub >) is equal to ()< sup > 2 </ sup > AU < sup > 3 </ sup >/ d < sup > 2 </ sup >.

The senses in each counterpart bear the impression only of phenomena that share its own frequency, whereas those upon all other frequencies are invisible, inaudible and intactible to them.

Once the operator took his finger off, the player would speed up until its tachometer was back in phase with the master, and as this happened, the phasing effect would appear to slide up the frequency spectrum.

Analog ( or analogue ) television is the analog transmission that involves the broadcasting of encoded analog audio and analog video signal: one in which the information to be transmitted, the brightness and colors of the points in the image and the sound waves of the audio signal are represented by continuous variations of some aspect of the signal ; its amplitude, frequency or phase.

It is a mathematical tool for finding repeating patterns, such as the presence of a periodic signal which has been buried under noise, or identifying the missing fundamental frequency in a signal implied by its harmonic frequencies.

However, a common and well-accepted metric is the half power points ( i. e. frequency where the power goes down by half its peak value ) on the output vs. frequency curve.

In case of a low-pass filter or baseband signal, the bandwidth is equal to its upper cutoff frequency.

Most commonly, bandwidth refers to the 3-dB bandwidth, that is, the frequency range within which the spectral density ( in W / Hz or V < sup > 2 </ sup >/ Hz ) is above half its maximum value ( or the spectral amplitude, in V or V / Hz, is more than 70. 7 % of its maximum ); that is, above − 3 dB relative to the peak.

The 3 dB bandwidth of an electronic filter or communication channel is the part of the system's frequency response that lies within 3 dB of the response at its peak, which in the passband filter case is typically at or near its center frequency, and in the lowpass filter is near 0 hertz.

This is the bandwidth of a device divided by its center frequency.

The plant occurs as a rare casual in the British Isles, mainly in southern England, but the frequency of its occurrence has declined greatly.

The station was later sold to RNC Media, but instead of renewing its license the CRTC issued RNC a license to launch a new radio station on the same frequency.

One clear benefit of the ' late arrival ' of the channel was that its frequency allocations at each transmitter had already been arranged in the early 1960s, when the launch of an ITV2 was highly anticipated.

At the subscriber's residence, either the subscriber's television or a set-top box provided by the cable company translates the desired channel back to its original frequency ( baseband ), and it is displayed on the screen.

However, the rapid growth of the world's population and its increased concentration often in hazardous environments has escalated both the frequency and severity of natural disasters.

The Nyquist – Shannon sampling theorem states that a signal can be exactly reconstructed from its samples if the sampling frequency is greater than twice the highest frequency of the signal ; but requires an infinite number of samples.