相关论文: Chirp Excitation
This paper proposes the use of a LoRa like chirp spread spectrum physical layer as the basis for a new Power Line Communication modulation scheme suited for low-bandwidth communication. It is shown that robust communication can be…
We consider the Thomson scattering of an electron in an ultra-intense chirped laser pulse. It is found that the introduction of a negative chirp means the electron enters a high frequency region of the field while it still has a large…
We consider a two-band superconductor with relative phase $\pi $ between the two order parameters as a model for the superconducting state in ferropnictides. Within this model we calculate the microwave response and the NMR relaxation rate.…
In this letter, we propose dual-mode chirp spread spectrum (DM-CSS) modulation for low-power wide-area networks. DM-CSS is capable of achieving a higher spectral efficiency (SE) relative to its counterparts, such as Long Range (LoRa)…
We present a model describing the use of ultra-short strong pulses to control the population of the excited level of a two-level quantum system. In particular, we study an off-resonance excitation with a few cycles pulse which presents a…
I describe a method for generating "shim pulses" for NMR spectroscopy and imaging (MRI) by taking advantage of the inherent inhomogeneity in the static and radiofrequency (RF) fields of a one-sided NMR system. The RF inhomogeneity here is…
The commonly used methods to characterize ultrafast laser pulses, such as frequency-resolved optical gating (FROG) and dispersion scan (d-scan), face problems when they are used on pulses with a chirp varying within the laser beam or the…
Accurately analyzing NMR and MRI diffusion experimental data relies on the theoretical expression used for signal attenuation or phase evolution. In a complex system, the encountered magnetic field is often inhomogeneous, which may be…
Numerically optimised microwave pulses are used to increase excitation efficiency and modulation depth in electron spin resonance experiments performed on a spectrometer equipped with an arbitrary waveform generator. The optimisation…
Existing optimal control protocols for mitigating the effects of relaxation and/or RF inhomogeneity on broadband pulse performance are extended to the more difficult problem of designing robust, refocused, frequency selective excitation…
The connection between the time-dependent physical spectrum of light and the phase space overlap of Wigner functions is investigated for optical pulses. Time and frequency properties of optical pulses with chirp are analyzed using the phase…
Particle accelerations by a 1D, EM, dispersive pulse in an external magnetic field are investigated. It is found that the well-known cyclotron resonance may be classified into three regimes as the length and/or the amplitude of the pulse…
The work is devoted to the problem of multiple signals of nuclear spin echoes in magnets, excited by a series of radio-frequency (RF) arbitrary duration pulses exceeding the free induction decay time. The quantum-statistical approach based…
Multi user orthogonal chirp spread spectrum (OCSS) can improve the spectral inefficiency of chirp spread spectrum (CSS) but is only feasible with perfect synchronism and without any channel dispersion. Asynchronism, channel dispersion, or…
We have developed experimental methods for the generation of chirped laser pulses of controlled frequency evolution in the nanosecond pulse length range for coherent atomic interaction studies. The pulses are sliced from the radiation of a…
Improving resolution and sensitivity will widen possible medical applications of magnetic particle imaging. Pulsed excitation promises such benefits, at the cost of more complex hardware solutions and restrictions on drive field amplitude…
Hyperpolarization methods in magnetic resonance overcome sensitivity limitations, especially for low-{\gamma} nuclei such as 13C and 15N. Signal Amplification By Reversible Exchange (SABRE) and extended SABRE (X-SABRE) are efficient and…
Synthetic aperture laser radar has higher resolution, so requires higher modulated bandwidth. Because the data volume of chirp or pulse coding schemes is too large, it brings much pressure to data acquisition and data processing. So, we can…
We propose a novel compressed sensing technique to accelerate the magnetic resonance imaging (MRI) acquisition process. The method, coined spread spectrum MRI or simply s2MRI, consists of pre-modulating the signal of interest by a linear…
We present a novel technique for producing pulses of laser light whose frequency is arbitrarily chirped. The output from a diode laser is sent through a fiber-optical delay line containing a fiber-based electro-optical phase modulator. Upon…