Pulse compression

pulse compression radarchirp radarintra-pulse modulationpulse compressingPulse Compressor
Pulse compression is a signal processing technique commonly used by radar, sonar and echography to increase the range resolution as well as the signal to noise ratio.wikipedia
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Sonar

asdicvariable depth sonaractive sonar
Pulse compression is a signal processing technique commonly used by radar, sonar and echography to increase the range resolution as well as the signal to noise ratio. In radar or sonar applications, linear chirps are the most typically used signals to achieve pulse compression.
The pulse may be at constant frequency or a chirp of changing frequency (to allow pulse compression on reception).

Matched filter

matched filteringmatched-filteringNorth filters
To detect the incoming signal, matched filtering is commonly used.
Pulse compression is an example of matched filtering.

Chirp compression

Chirp compression
The chirp pulse compression process transforms a long duration frequency-coded pulse into a narrow pulse of greatly increased amplitude.

Barker code

The precise way of choosing the sequence of phases is done according to a technique known as Barker codes.
Barker codes of length N equal to 11 and 13 are used in direct-sequence spread spectrum and pulse compression radar systems because of their low autocorrelation properties (The sidelobe level of amplitude of the Barker codes is 1/N that of the peak signal).

Radar

radar stationradarsradar system
Pulse compression is a signal processing technique commonly used by radar, sonar and echography to increase the range resolution as well as the signal to noise ratio. In radar or sonar applications, linear chirps are the most typically used signals to achieve pulse compression.
The pulse is often modulated to achieve better performance using a technique known as pulse compression.

Chirp

chirp functionChirp modulationchirp signal
In radar or sonar applications, linear chirps are the most typically used signals to achieve pulse compression.
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).

Signal processing

signal analysissignalsignal processor
Pulse compression is a signal processing technique commonly used by radar, sonar and echography to increase the range resolution as well as the signal to noise ratio.

Ultrasound

ultrasonicultrasonicsultrasounds
Pulse compression is a signal processing technique commonly used by radar, sonar and echography to increase the range resolution as well as the signal to noise ratio.

Angular resolution

spatial resolutionresolutionresolved
Pulse compression is a signal processing technique commonly used by radar, sonar and echography to increase the range resolution as well as the signal to noise ratio.

Signal-to-noise ratio

signal to noise ratioSNRsignal-to-noise
Pulse compression is a signal processing technique commonly used by radar, sonar and echography to increase the range resolution as well as the signal to noise ratio.

Modulation

modulatedmodulatordigital modulation
This is achieved by modulating the transmitted pulse and then correlating the received signal with the transmitted pulse.

Cross-correlation

cross correlationcorrelationcorrelating
This is achieved by modulating the transmitted pulse and then correlating the received signal with the transmitted pulse.

Carrier frequency

command frequenciescarrier frequenciesfrequencies
The simplest signal a pulse radar can transmit is a sinusoidal-amplitude pulse, A and carrier frequency, f_0, truncated by a rectangular function of width,.

Doppler effect

Dopplerdoppler shiftDoppler shifts
The return signal, written, is an attenuated and time-shifted copy of the original transmitted signal (in reality, Doppler effect can play a role too, but this is not important here.) There is also noise in the incoming signal, both on the imaginary and the real channel, which we will assume to be white and Gaussian (this generally holds in reality); we write to denote that noise.

White noise

whitestaticnoise
The return signal, written, is an attenuated and time-shifted copy of the original transmitted signal (in reality, Doppler effect can play a role too, but this is not important here.) There is also noise in the incoming signal, both on the imaginary and the real channel, which we will assume to be white and Gaussian (this generally holds in reality); we write to denote that noise.

Normal distribution

normally distributednormalGaussian
The return signal, written, is an attenuated and time-shifted copy of the original transmitted signal (in reality, Doppler effect can play a role too, but this is not important here.) There is also noise in the incoming signal, both on the imaginary and the real channel, which we will assume to be white and Gaussian (this generally holds in reality); we write to denote that noise.

Additive white Gaussian noise

additive noiseAWGNadditive
This method is optimal when a known signal is to be detected among additive white Gaussian noise.

Convolution

convolvedconvolvingkernel
This is achieved by convolving the incoming signal with a conjugated and time-reversed version of the transmitted signal.

Complex conjugate

complex conjugationconjugateconjugation
This is achieved by convolving the incoming signal with a conjugated and time-reversed version of the transmitted signal.

Rectangular function

rectangle functionbox filterbox function
The simplest signal a pulse radar can transmit is a sinusoidal-amplitude pulse, A and carrier frequency, f_0, truncated by a rectangular function of width,.

Sinc function

sinccardinal sine functionnormalized sinc function
Around 0, this function behaves as the sinc (or cardinal sine) term, defined here as.

Side lobe

sidelobelobesidelobes
Since the cardinal sine can have annoying sidelobes, a common practice is to filter the result by a window (Hamming, Hann, etc.).

Phased array

phased array radarphased-arrayphased-array radar
In addition, the effective wavelength of the electromagnetic wave changes during the frequency sweep of a chirp signal, and therefore the antenna look direction will be inevitably changed in a Phased array system.

Phase modulation

phase modulatedPMphase-modulated
Phase modulation is a commonly used technique; in this case, the pulse is divided in time slots of duration for which the phase at the origin is chosen according to a pre-established convention.

Spread spectrum

spread-spectrumdigital frequency spectrumdigital spread spectrum
Spread spectrum