A chirp is a signal in which the frequency increases ('up-chirp') or decreases ('down-chirp') with time. It is commonly used in sonar and radar, but has other applications, such as in spread spectrum communications. In spread spectrum usage, SAW devices such as RACs are often used to generate and demodulate the chirped signals. In optics, ultrashort laser pulses also exhibit chirp due to the dispersion of the materials they propagate through. Blackbird (Turdus merula), singing male. ... Stridulation is the act of producing sound by rubbing together certain body parts. ... In telecommunication, the term chirping has the following meanings: 1. ... A walkie-talkie is a portable, bi-directional radio transceiver, first developed for military use. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... The title of this article is incorrect because of technical limitations. ... This article or section is not written in the formal tone expected of an encyclopedia article. ... In information theory, a signal is the sequence of states of a communications channel that encodes a message. ... FreQuency is a music video game developed by Harmonix and published by SCEI. It was released in November 2001. ... The F70 type frigates (here, La Motte-Picquet) are fitted with VDS (Variable Depth Sonar) type DUBV43 or DUBV43C towed sonars SONAR (SOund Navigation And Ranging) â€” or sonar â€” is a technique that uses sound propagation under water (primarily) to navigate, communicate or to detect other vessels. ... This long range radar antenna, known as ALTAIR, is used to detect and track space objects in conjunction with ABM testing at the Ronald Reagan Test Site on the Kwajalein atoll. ... Spread-spectrum telecommunications is a technique in which a signal is transmitted in a bandwidth considerably greater than the frequency content of the original information. ... A surface acoustic wave (SAW) is a kind of wave used in piezoelectric devices called SAW devices in electronics circuits. ... For the book by Sir Isaac Newton, see Opticks. ... In optics, an ultrashort pulse of light is an electromagnetic pulse whose time duration is on the order of the femtosecond ( second). ... Experiment with a laser (US Military) In physics, a laser is a device that emits light through a specific mechanism for which the term laser is an acronym: Light Amplification by Stimulated Emission of Radiation. ... Dispersion can mean any of several things: A phenomenon that causes the separation of a wave into components of varying frequency. ...

A linear chirp waveform; a sinusoidal wave that increases in frequency linearly over time

In a linear chirp, the instantaneous frequency f(t ) varies linearly with time: Image File history File links Download high resolution version (1250x875, 94 KB) A graph of a sinusoidal linear chirp. ... Image File history File links Download high resolution version (1250x875, 94 KB) A graph of a sinusoidal linear chirp. ... In signal processing, a general sinusoidal signal with constant amplitude can be defined as: where is the amplitude, and is the instantaneous phase (or local phase or simply phase) . The simplest useful form is: which is effectively the same as the cyclical form: , where mod is the Modulo_operation. ...

f(t) = f₀ + kt

where f₀ is the starting frequency (at time t = 0), and k is the rate of frequency increase or chirp rate. A corresponding time-domain function for a sinusoidal chirp is: Chirp rate is the instantaneous rate of change of the frequency of a waveform. ... In mathematics, the trigonometric functions are functions of an angle, important when studying triangles and modeling periodic phenomena. ...

An exponential chirp waveform; a sinusoidal wave that increases in frequency exponentially over time

In a geometric chirp, the frequency of the signal varies with a geometric relationship over time. In other words, if two points in the waveform are chosen, t₁ and t₂, and the time interval between them t₂ − t₁ is kept constant, the frequency ratio f(t₂)/f(t₁) will also be constant. Image File history File links Linchirp. ... Software development stages In computer programming, development stage terminology expresses how the development of a piece of software has progressed and how much further development it may require. ... Image File history File links Download high resolution version (1250x875, 86 KB) A graph of a sinusoidal exponential chirp. ... Image File history File links Download high resolution version (1250x875, 86 KB) A graph of a sinusoidal exponential chirp. ... Diagram showing the geometric series 1 + 1/2 + 1/4 + 1/8 + ... which converges to 2. ...

In an exponential chirp, the frequency of the signal varies exponentially as a function of time: The exponential function is one of the most important functions in mathematics. ...

f(t) = f₀k^t

where f₀ is the frequency at t=0, and k is the rate of exponential increase in frequency. A corresponding sinusoidal chirp waveform would be defined by: In mathematics, exponential growth (or geometric growth) occurs when the growth rate of a function is always proportional to the functions current size. ...

Although somewhat harder to generate, the geometric type does not suffer from reduction in correlation gain if Doppler-shifted by a moving target. This is because the Doppler shift actually scales the frequencies of a wave by a multiplier (shown below as the constant c). Image File history File links Expchirp. ... Software development stages In computer programming, development stage terminology expresses how the development of a piece of software has progressed and how much further development it may require. ... Positive linear correlations between 1000 pairs of numbers. ... A source of waves moving to the left. ...

f(t)_Doppler = cf(t)_Original

From the equations above, it can be seen that this actually changes the rate of frequency increase of a linear chirp (kt multiplied by a constant) so that the correlation of the original function with the reflected function is low.

Because of the geometric relationship, the Doppler shifted geometric chirp will effectively start at a different frequency (f₀ multiplied by a constant), but follow the same pattern of exponential frequency increase, so the end of the original wave, for instance, will still overlap perfectly with the beginning of the reflected wave, and the magnitude of the correlation will be high for that section of the wave.

A chirp signal can be generated with analog circuitry via a VCO, and a linearly or exponentially ramping control voltage. It can also be generated digitally by a DSP and DAC, perhaps by varying the phase angle coefficient in the sinusoid generating function. It has been suggested that this article or section be merged with Analog electronics. ... A voltage-controlled oscillator or VCO is an electronic circuit that uses amplification, feedback, and a resonant circuit to generate a repeating voltage waveform. ... International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ... A digital system is one that uses discrete values (often electrical voltages), especially those representable as binary numbers, or non-numeric symbols such as letters or icons, for input, processing, transmission, storage, or display, rather than a continuous spectrum of values (ie, as in an analog system). ... A digital signal processor (DSP) is a specialized microprocessor designed specifically for digital signal processing, generally in real-time. ... In electronics, a digital-to-analog converter (DAC or D-to-A) is a device for converting a digital (usually binary) code to an analogue signal (current, voltage or charges). ...

Chirp modulation

Chirp modulation, or linear frequency modulation for digital communication was patented by Sidney Darlington [[1]]in 1954 with significant later work performed by Winkler in 1962. This type of modulation employs sinusoidal waveforms whose instantaneous frequency increases or decreases linearly over time. These waveforms are commonly referred to as linear chirps or simply chirps. Hence the rate at which their frequency changes is called the chirp rate. In binary chirp modulation, binary data is transmitted by mapping the bits into chirps of opposite chirp rates. For instance, over one bit period "1" is assigned a chirp with positive rate a and "0" a chirp with negative rate −a. Chirps have been heavily used in radar applications and as a result advanced sources for transmission and matched filters for reception of linear chirps are available[2].

Chirplet transform

Main article: Chirplet transform

(a) In image processing, we seldom have direct periodicity, but, rather, we encounter periodicity-in-perspective. (b) Repeating structures like the alternating dark space inside the windows, and light space of the white cement, "chirp" (increase in frequency) to towards the right. (c) Thus the best fit chirp for image processing is often a projective chirp.

Another kind of chirp is the projective chirp, of the form , having the three parameters a (scale), b (translation), and c (chirpiness). The projective chirp is ideally suited to image processing, and forms the basis for the projective chirplet transform. Comparison of wave, wavelet, chirp, and chirplet In signal processing, the chirplet transform is an inner product of an input signal with a family of analysis primitives called chirplets. ... Image File history File links p-type chirplets are useful for image processing I took this picture of the red building and drew a graph through it, to show the chirplet transform, how projective (p-type) chirps operate. ... Image File history File links p-type chirplets are useful for image processing I took this picture of the red building and drew a graph through it, to show the chirplet transform, how projective (p-type) chirps operate. ... UPIICSA IPN - Binary image Image processing is any form of information processing for which the input is an image, such as photographs or frames of video; the output is not necessarily an image, but can be for instance a set of features of the image. ... Comparison of wave, wavelet, chirp, and chirplet In signal processing, the chirplet transform is an inner product of an input signal with a family of analysis primitives called chirplets. ...

See also

• Chirplet transform — A signal representation based on a family of localized chirp functions, each member of which can usually be expressed as parameterized transformations of each other.
• Pulse compression - A signal processing technique designed to maximize the sensitivity and resolution of radar systems by modifying transmitted pulses to improve their auto-correlation properties. One way of accomplishing this is to chirp the RADAR signal (also known as Chirp Radar).