Spectrum analyzer

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

AFC frequency synchronization network

Abstract: A frequency synchronization network is disclosed that is particularly suited for a Eureka-147 system transmitting synchronization symbols and multiple data carriers, wherein the multiple carriers are transmitted simultaneously and separated from each other by a bin quantity. The network comprises a Fast Fourier transform (FFT) network, a complex rotation device, and a power analyzer. The power analyzer determines the peak condition of the FFT bin quantities and routes this information to an interpolation sequence that determines the zero-crossover condition of the peak bin quantity, and which ultimately determines an output as the frequency offset of the AFC frequency symbol. The frequency offset quantity is provided to an automatic frequency control (AFC) network to provide for frequency locking of the transmitting and receiving elements of the Eureka-147 system.

A real-time autoregressive spectrum analyzer for Doppler ultrasound signals

Abstract: A system based on a digital signal processor and a microcomputer has been programmed to estimate the maximum entropy autoregressive (AR) power spectrum of ultrasonic Doppler shift signals and display the results in the form of a sonogram in real-time on a computer screen. The system, which is based on a TMS 320C25 digital signal processor chip, calculates spectra with 128 frequency components from 64 samples of the Doppler signal. The samples are collected at a programmable rate of up to 40.96 kHz, and the computation of each spectrum takes typically 3.2 ms. The feasibility of on-line AR spectral estimation makes this type of analysis an attractive alternative to the more conventional fast Fourier transform approach to the analysis of Doppler ultrasound signals.

Non-invasive blood glucose meter

Abstract: A non-invasive blood glucose meter includes a near-infrared energy analyzer which includes a light filter assembly of two Fabry-Perot interferometers and a photosensor. The near-infrared energy analyzer detects near-infrared energy absorbed by a human or animal body and generates spectra of such absorption so that the blood glucose content in the body may be analyzed. In order to provide stable energy absorption information of the blood, special designs are provided to stabilize the light source, to calibrate the spectrum and to obviate the noise from the heartbeats of the body. A single crystal silicon elastic power source is used to provide the driving power of the Fabry-Perot interferometer to avoid mechanical hysteresis.

Noise characterization of mode-locked color-center laser sources

Abstract: By using an ultrahigh-speed photodetector and wide bandwidth spectrum analyzer combinations, a noise characterization of the pulse train from a mode-locked KCl:Tl color-center laser has been performed. Amplitude and phase (timing jitter) noise content are quantified and compared when the laser is operated in both synchronously mode-locked and coupled-cavity mode-locked configurations. By deliberately mismatching the color-center laser cavity frequency with respect to that of the Nd:YAG pump-laser and examining resultant noise burst power spectra, it has been confirmed that the coupled-cavity mode-locking process exhibits passive characteristics. >

Method for detecting and locating sources of communication signal interference employing both a directional and an omni antenna

Abstract: A communication interference detection method determines the direction toward a source of interference by combining interference signals from a sweeping directional antenna with communication signals from an omni antenna while measuring and recording power, frequency spectra, and interference-to-signal ratio over a wide range of conditions using a spectrum analyzer and power meter and communication receivers. The method can be used in the field to locate interfering sources which might interference with the reception of communication signals such as Global Position System (GPS) communication signals.