Related Experiment Video
Updated: Mar 28, 2026
08:39
Shaping the Amplitude and Phase of Laser Beams by Using a Phase-only Spatial Light Modulator
Published on: January 28, 2019
10.5K
Watermarking of linear frequency modulated pulses using chirplet graphs and stretch processing.
Bijan G Mobasseri1, Anirudh Nimbagal2
1Electrical and Computer Engineering Department, Villanova University, 800 Lancaster Avenue, Villanova, Pennsylvania 19085, USA bijan.mobasseri@villanova.edu.
The Journal of the Acoustical Society of America
|January 3, 2016
Summary
This study introduces a novel method to watermark sonar pulses using chirplets embedded in a graph. This technique enables reliable identification of sonar ping sources for applications like search and rescue.
Area of Science:
- Underwater acoustics
- Signal processing
- Information embedding
Background:
- Identifying the source of sonar pings is crucial for underwater operations.
- Existing methods may lack robustness or require complex processing.
Purpose of the Study:
- To propose a new methodology for watermarking sonar pulses.
- To enable reliable source identification of sonar signals.
Main Methods:
- Embedding sonar pulses with a chain of low-power chirplets represented by a graph.
- Utilizing stretch processing for watermark detection.
- Focusing chirplet energies on a single beat frequency for detection.
Main Results:
- Successful watermark detection was achieved when the graph traversal path matched the transmission path.
- The algorithm demonstrated effectiveness in simulations within shallow water environments.
- Performance was evaluated across varying ranges.
Conclusions:
- The proposed chirplet-based watermarking method offers a robust approach for sonar source identification.
- This technique has potential applications in search and rescue and other underwater acoustic scenarios.
- Further validation in diverse underwater conditions is warranted.
Related Concept Videos
01:24IR Frequency Region: X–H Stretching
1.7K
In IR spectroscopy, signals produced by the X−H bonds (such as C−H, O−H, or N−H) can be observed in the frequency range of 2700–4000 cm–1. The C−H stretching vibration forms sharp bands in the region 2850–3000 cm–1. The presence of the O−H stretching vibration leads to the forming of an absorption band in the frequency range 3650–3200 cm−1. At the same time, N−H stretching can be confirmed by absorption bands in...
1.7K
01:20Transformations of Functions III
277
Transformations modify the graphical representation of a function without changing its fundamental form. One common transformation is reflection, which flips the graph across a designated axis. When the vertical coordinates of all points are multiplied by the negative one, the entire graph is mirrored over the horizontal axis. This transformation reverses the vertical orientation of peaks and troughs, akin to signal inversion in electrical systems, where a waveform is flipped, but the timing of...
277
01:17Bandpass Sampling
612
In signal processing, bandpass sampling is an effective technique for sampling signals that have most of their energy concentrated within a narrow frequency band. This type of signal is known as a bandpass signal. The key principle of bandpass sampling involves sampling the signal at a rate that is greater than twice the signal's bandwidth to prevent aliasing.
A bandpass signal has a spectrum with a lower frequency limit, denoted as ω1, and an upper frequency limit, denoted as ω2....
A bandpass signal has a spectrum with a lower frequency limit, denoted as ω1, and an upper frequency limit, denoted as ω2....
612
01:10Reconstruction of Signal using Interpolation
831
Signal processing techniques are essential for accurately converting continuous signals to digital formats and vice versa. When a continuous signal is sampled with a period T, the resulting sampled signal exhibits replicas of the original spectrum in the frequency domain, spaced at intervals equal to the sampling frequency. To handle this sampled signal, a zero-order hold method can be applied, which creates a piecewise constant signal by retaining each sample's value until the next...
831
01:11Sampling Continuous Time Signal
835
In signal processing, a continuous-time signal can be sampled using an impulse-train sampling technique, followed by the zero-order hold method. Impulse-train sampling involves the use of a periodic impulse train, which consists of a series of delta functions spaced at regular intervals determined by the sampling period. When a continuous-time signal is multiplied by this impulse train, it generates impulses with amplitudes corresponding to the signal's values at the sampling points.
In the...
In the...
835
01:20¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
1.8K
When proton-coupled carbon-13 spectra are simplified by a broadband proton decoupling technique, structural information about the coupled protons is lost. Distortionless enhancement by polarization transfer (DEPT) is a technique that provides information on the number of hydrogens attached to each carbon in a molecule. While the DEPT experiment utilizes complex pulse sequences, the pulse delay and flip angle are specifically manipulated. The resulting signals have different phases depending on...
1.8K