Spectrum analyzer

About: Spectrum analyzer is a research topic. Over the lifetime, 12217 publications have been published within this topic receiving 101851 citations.

An FPGA-based frequency response analyzer for multisine and stepped sine measurements on stationary and time-varying impedance

Abstract: We report the development of a field programmable gate array (FPGA) based frequency response analyzer (FRA) for impedance frequency response function (FRF) measurements using periodic excitations, i.e. sine waves and multisines. The stepped sine measurement uses two dedicated hardware-built digital embedded multiplier blocks to extract the phase and quadrature components of the output signal. The multisine FRF measurements compute the fast Fourier transform (FFT) of the input/output signals. In this paper, we describe its design, implementation and performance evaluation, performing electrical impedance spectroscopy (EIS) measurements on phantoms. The stepped sine accuracy is 1.21% at 1 kΩ (1%), the precision is 35 mΩ and the total harmonic distortion plus noise (THD+N) is −120 dB. As for the multisine impedance FRF measurements, the magnitude and phase precision are, respectively, 0.23 Ω at 48.828 kHz and 0.021 deg at 8.087 MHz when measuring a resistor 505 Ω (1%). The magnitude accuracy is 0.55% at 8.087 MHz while the phase accuracy is 0.17 deg at 6.54 MHz. In all, the stepped sine signal-to-noise ratio (SNR) is 84 dB and 65 dB at frequencies below and above 1 MHz respectively. The SNR for the multisine FRF measurements is above 65 dB (30 kHz–10 MHz). The FRA bandwidth is 610.4 mHz–12.5 MHz and the maximum FRF measurement rate exciting with multisines starting at 30 kHz is 200 spectra s−1. Based on its technical specifications and versatility, the FRA presented can be used in many applications, e.g. for getting insight quickly into the instantaneous impedance FRF of the time-varying impedance under test.

Real-time cyclostationary analysis for cognitive radio via software defined radio

Abstract: Cyclostationary analysis such as spectral correlation function (SCF) and spectral coherence function (SOF) has been accepted as an important tool in signal detection and radio frequency (RF) parameter estimation in cognitive radios. However, cyclostationary analysis requires extremely high resolution to fully observe the cyclic frequency features, leading to very high computational complexity and difficulty in real time implementation, especially on software defined radios where computational capability is limited. In this paper, we implement and demonstrate a real time SCF/SOF RF signal analyzer by adopting previously proposed two-stage dynamic resolution SCF/SOF estimation method using software defined radios. Specifically, high resolution SCF/SOF calculation is only performed near the expected cyclic feature locations obtained through a low complexity coarse estimation employing spectral analysis. This cyclostationary analysis based RF signal analyzer is capable of sensing the existence of primary users and estimating the carrier frequency and symbol rate accurately. Using Universal Software Radio Peripheral (USRP) software defined radio platform and GNU radio software, we implement and demonstrate such a cyclostationary analysis based RF signal analyzer in real time and validate the performance in realistic wireless communication channels.

On-chip spectrum analyzer for analog built-in self test

Abstract: This paper presents the design of an on-chip spectrum analyzer. A novel architecture is used to mitigate the problems encountered in trying to implement architectures employed in conventional stand-alone instruments on a chip. Specifically, it makes use of a very-low IF architecture, which leads to a highly compact design, that can be used for measuring the frequency content of high frequency on-chip signals. The architecture and design considerations along with an implementation in a 0.18 /spl mu/ CMOS process is described. The design takes up an area of approximately 0.384 mm/sup 2/ with a simulated frequency range of 33 MHz to 3 GHz and a dynamic range of 60 dB.

Spectral analyzer for measuring the thickness and identification of chemicals of organic thin films using cars microscopy

Abstract: The present invention relates to a spectral analyzer using a CARS microscopy which can measure the thickness and identification of kinds of chemicals of organic thin films at high spatial precision using a non-destructive method The spectral analyzer using the CARS microscopy according to the present invention measures the wavelength and intensity of the coherent anti- stakes Raman scattering (CARS) signals scattered by irradiating stokes beam and pump beam to the thin films to measure the thickness of the thin films and to analyze the chemicals The spectral analyzer using the CARS microscopy according to the present invention is based on a vacuum spectroscopy corresponding to a vibration mode of a molecule by using a CARS microscopy that is one of third-order non- linear optical phenomenons, making it possible to analyze each component, measure the components non- invasive Iy and in real time, and overcome a general diffraction limitation of spatial resolution

Stereopsis-Inspired Time-Stretched Amplified Real-Time Spectrometer (STARS)

Abstract: We introduce and demonstrate a single-shot real-time optical vector spectrum analyzer (VSA). This simple and powerful instrument combines amplified dispersive Fourier transform with stereopsis reconstruction algorithm and is inspired by binocular vision in biological eyes. Moreover, a dynamic time-stretch concept is employed to dramatically enhance the phase reconstruction accuracy and dynamic range for ultrashort optical signals (>; 30 times). We show that, using a noniterative analytical expression, the phase profile of the input signal can be reconstructed using intensity-only measurements. The proposed method is experimentally proved by fully characterizing the time-varying amplitude and phase of single-shot THz-bandwidth optical signals, with durations ranging from sub-ps to 35 000 ps, with ultrasmall to ultralarge temporal phase variations and at 25-MHz update rate. We have also used this instrument to characterize the amplitude and phase of a prechirped 40-Gbps DQPSK optical signal using a 1.5-GHz digitizer and without using a reference signal.