Detection of sonar sinusoids of unknown frequency and known or unknown phase by F. S. Hill

Cover of: Detection of sonar sinusoids of unknown frequency and known or unknown phase | F. S. Hill

Published by Rand Corp. in Santa Monica, Calif .

Written in English

Read online


  • Sonar.

Edition Notes

Book details

Statement[by] F. S. Hill, Jr.
Series[Rand Corporation] Memorandum, RM-4809-ARPA, Research memorandum (Rand Corporation) ;, RM-4809-ARPA.
ContributionsUnited States. Advanced Research Projects Agency.
LC ClassificationsQ180.A1 R36 no. 4809
The Physical Object
Paginationxi, 64 p.
Number of Pages64
ID Numbers
Open LibraryOL5978229M
LC Control Number66005560

Download Detection of sonar sinusoids of unknown frequency and known or unknown phase

Detection of Sonar Sinusoids of Unknown Frequency and Known or Unknown Phase. by the phase of the signal is known, thus allowing coherent detection; the second acknowledges that the initial phase could not be known, and an analysis of the incoherent detector is made. the initial phase is known, the gaussian character of the quantities.

Detection of Sonar Sinusoids of Unknown Frequency and Known or Unknown Phase Author: Francis S. Hill Subject: A consideration of the problem of detecting a constant sine wave of unknown frequency and amplitude in gaussian noise.

Created Date: 9/9/ PM. arpa order no. io memorandum -rmarpa i december detection of sonar sinusoids of unknown frequency and known or unknown phase f.

hill, jr. The problem of rejection of a sinusoidal disturbance of known frequency, acting at the output of a discrete-time complex-valued linear stable plant with unknown dynamics, is considered.

represent the tone amplitude, frequency and phase, respec-tively. We consider unknown A1 and f1 while w1 is either known or unknown. The first hypothesis H0 assumes that x[n] consists only of noise while in H1, the sinusoid is pre-sumed to be present. The second detection.

detection process, ranging from the detection of unknown (and noise like) signals in noise to the detection of sinusoidal signals of known frequency, phase and amplitude in noise.

The input noise, in most studies, has been assumed to be Gaussian for mathematical simplicity. is the frequency of the signal, is the initial phase and is an additive noise process.

Noise is assumed to be Gaussian white noise process with ]=0 (being the expectation functional) and var [ ] = σ2. Assuming that all the above parameters are unknown, we try to get an estimate for the frequency as ̂.

The frequency estimator under consideration is a second-order filter designed for the estimation of the frequency of a sinusoid with unknown amplitude, frequency, and phase. When we cannot be fooled by the large side-lobes of Detection of sonar sinusoids of unknown frequency and known or unknown phase book rectangular window transform (e.g., when the sinusoids under analysis are known to be well separated in frequency), the rectangular window truly is the optimal window for the estimation of frequency, amplitude, and phase of a sinusoid in the presence of stationary noise [,].

A compromise emerges, such that the optimal frequency must be carefully selected in proportion to the size of the desired detail.

Sonar isn’t solely used for surveillance or by warfare submarines; it is also used by doctors to detect cysts and cancerous cells, a process which is known. Sonar systems are generally used underwater for range finding and detection.

Active sonar emits an acoustic signal, or pulse of sound, into the water. The sound bounces off the target object and returns an “echo” to the sonar transducer.

Unlike active sonar, passive sonar does not emit its own signal, which is an advantage for military vessels.

To demonstrate that the proposed HOS can detect nonlinearity in the case of the known nonlinear polynomial frequency variation, a transient random sinusoidal excitation with constant amplitude, random initial phase and quadratically changed instantaneous frequency in time (i.e., the second order chirp) has been passed via the following.

To make a steered line array, we apply a linear phase shift −zksinθ0 to the excitation of the array: dp = A/L eiz(ksinθ− 0)eiωtdz (1) r We can write sinθ0 zksinθ0 = ωz c zsinθ0 zksinθ0 = ωT0(z);T0(z)= c The phase term is equivalent to a time delay T0(z) that varies with position along the line array.

We can re-write the phase term. Thus, by operating the sonar in a known environment (with known Z 0), estimating the re ection coe cient from a plane interface to an unknown medium, the char-acteristic impedance Z can be calculated, and thereby the material properties determined.

Table II lists the characteristic impedance to a few di erent media. Note. The spectrum of sonar frequency spans from a few Kilohertz or less for long-range target detection to medium range of kHz for target detection and classification.

For short-range scanning of high resolution, higher frequencies of kHz are commonly used. Most static radar and sonar platforms are. Sonar (sound navigation ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, communicate with or detect objects on or under the surface of the water, such as other vessels.

Two types of technology share the name "sonar": passive sonar is essentially listening for the sound made by vessels; active sonar is emitting pulses of sounds. where I s is the intensity of the transmitted signal measured at 1 m distance from the source.

The reference intensity, I ref, is the intensity of a sound wave having a root mean square (rms) pressure of 1 level is sometimes written in dB// 1 μPa, but actually is referenced to the intensity of a.

Detection Threshold for Sonar. Sonar (SOund Naviation And Ranging) is a technology that uses acoustical waves to detect and locate objects in the ocean. Active sonar systems, such as fish finders, echosounders, side-scan sonars, and military sonars, transmit a pulse of sound and then listen for echoes.

Passive sonar systems listen to underwater sounds to detect signals of interest, such as. This quantity, known as Detection Threshold (DT), attempts to describe in a single number everything that happens once the signal and its accompanying noise are received at the sonar.

Detection threshold is defined as the signal minus noise level required inboard of the hydrophone array in order that an operator can detect a target. The frequency of the sinusoid is not known.

It is only assured to be in the range of Hz. Different "beeps" will be at the same center frequency but amplitudes may vary. $\endgroup$ –. Time-Frequency Sonar Processing 0. Sonar (for “sound navigation and ranging”) and Radar (for “radio detection and ranging”) were originally used for finding the distances and velocities of targets.

They have evolved to scanning systems that are capable of localizing, identifying, and classifying targets. Doppler Shift (Passive Sonar) When a sound source is moving with respect to an acoustic observer, the frequency of the sound is shifted. 0 = f. c + V. c - V.

0 = observed frequency f. s = frequency at the source c = speed of sound V. 0 = speed of observer approaching sound source = V. cos. s = speed of source. SONAR (sound navigation and ranging) systems have many similarities to RADAR and electro-optical systems.

Again, detection is based on the propagation of waves between the target and detector. There are active sonar systems, where the wave propagates from the transmitter to the target and back to the receiver, analogous to pulse-echo radar.

Covariance Estimation for Signals with Unknown Means Covariance Estimation for Signals with Unknown Means (cont’d) Unbiased ACS Estimates may lead to Negative Spectral Estimates Variance of Estimated ACS Another Proof of the Equality ˚^p(!) = ˚^c(!) A Compact Expression for the Sample ACS.

Detection, Estimation, and Modulation Theory: Radar-Sonar Signal Processing and Gaussian Kam P and Chui C Adaptive sequence detection for MPSK/MQAM with unknown carrier phase characteristics Proceedings of the IEEE conference on Wireless Communications & Networking Conference, () Rosa-Zurera M, Jarabo-Amores M and Gil-Pita R.

Its primary use is to measure the power of the spectrum of known and unknown signals. By comparison, the vector signal analyzer measures the magnitude and phase. SONAR Systems and Underwater Signal Processing: Classic and Modern Approaches SONAR systems, the measured signals, known as contacts, are reflected either from targets or from other undesired sources.

In the latter case, the measured signal is known as a false alarm or clutter as mentioned before. In the case of the Deeper START, its kHz sonar frequency means surface clutter can reach down to 1 meter / ft. below the surface of the water. The image below illustrates 2 different situations where surface clutter can affect your sonar readings – (in these examples the surface clutter extends to approximately 1 meter / ft.

below. “How far is the distance of sonar detection?” Thanks for the A2A. The question is very broad, and an exact answer would be classified, of course. I assume you’re asking about detecting a submarine. There are two “modes” (as other answers have said. Active sonar creates a pulse of sound, often called a "ping" and then listens for reflections of the pulse.

The pulse may be at a constant frequency or a chirp of changing it's a chirp, the receiver correlates the frequency of the reflections to the known chirp. Mid-frequency active sonar (1kHzkHz) is the Navy’s primary tactical sonar and its main tool to combat the threat posed by the world-wide proliferation of ultra-quiet diesel submarines.

In the wrong hands, these stealthy submarines are capable of inflicting serious damage on high value assets like aircraft carriers and amphibious assault.

More about SONAR. Unlike radar, sonar is a natural method used by some animals (such as bats and sharks) for navigation. Sonar was developed before the radar and was used in WWI, to locate the submarines and mines in the sea. Acoustic location in the air was used even before radar. Sonar uses acoustic waves (sound waves) for detection.

SONAR Equation. The “sonar equation” is a systematic way of estimating the expected signal-to-noise ratios for sonar (SOund Navigation And Ranging) systems. The signal-to-noise ratio determines whether or not a sonar will be able to detect a signal in the presence of background noise in the ocean.

MAQ Sonar specializes in omni ° directional commercial fishing sonar built to be the best solution for shallow water, near surface and pelagic species fishing.

With no more blind areas to think about, the operator can focus on the tilt, range and fishing area. For Commercial Fishing, Seabed Profiling, Marine Professionals and Super Yacht. Polydoros and C.

Nikias, “Detection of Unknown-Frequency Sinusoids in Noise via Autoregressive Modeling,” Proceedings of the IEEE International Conference on Acoustics, Speech, and Signal Processing, pp. Tokyo, Japan, April Underwater Target Detection with an Active Sonar System. Open Script. The hydrophone is a single isotropic element and has a frequency range from 0 to 30 kHz, which contains the operating frequency of the multipath channel.

Specify the hydrophone voltage sensitivity as dB. 1 day ago  The state of the art for synthetic aperture sonar (SAS) is strongly coupled to constraints on the way it can be used [1,2,3].For example, the k sensor poses often have to be equidistantly placed on a virtual line perpendicular to the sensor.

This is motivated by the intention to ease the signal processing as well as by practical aspects: a vehicle, for example, a surface vessel or an. The form of the least-squares estimator in the known-frequency case immediately suggests the following frequency estimator for the unknown-frequency case: () That is, the sinusoidal frequency estimate is defined as that frequency which maximizes the DTFT magnitude.

receivers. A frequency modulated signal with special filters ensures detection and identification of fish even under difficult conditions, and without losing the large distance range. The SH transducer which is used in this thesis is a Simrad transducer. The production of these sonars involves testing of the sonar.

SONAR usually operates at frequencies in –50, Hz range. Higher higher frequencies provide more accurate location data, but propagation losses (i.e. loss of signal strength over distance) also increase with frequency. The Sonar will then rotate a further 6 degrees and repeat the process. In this way, Searchlight Sonar can search a wide area sequentially.

High frequency ultrasonic waves take a comparatively long time travelling through the water, and this can limit the search speed. Due to the narrow beam transmitted, sometimes the Sonar will not display the.Learn sonar with free interactive flashcards. Choose from different sets of sonar flashcards on Quizlet.

Just started using Sonarr and so far it’s great. Managed to figure out most things but this has me stumped. Added a new series, Thewhich I had some but not all of the episodes. Sonarr recognises the series, finds it on my network, and renames everything without any problems.

Clicking Search for all episodes results in the missing episodes not being downloaded. Clicking manual search.

55582 views Thursday, November 26, 2020