Spectrum analyzer

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

System and methods for sample analysis

Abstract: The invention encompasses analyzers and analyzer systems that include a single particle analyzer, methods of using the analyzers and analyzers systems to analyze samples, either for single particles or for multiple particles (multiplexing), methods of doing business based on the use of the analyzers or analyzer systems of the system, and electronic media for storing parameters useful in the analyzers and analyzer systems of the invention.

Phase noise measurements utilizing a frequency down conversion/multiplier, direct spectrum measurement technique

Abstract: An improved circuit for phase noise measurements utilizing a frequency down conversion/multiplier and direct spectrum measurement technique which uses a combination of a phase detector method and a direct spectrum approach. The circuit is particularly useful for field test environments where laboratory instrumentation is normally not available, and fast and accurate phase noise measurements are required. The phase noise measuring circuit includes a frequency mixer which has a first input signal from a device under test and a second input signal from a reference stable oscillator having ultra low phase noise with a fixed center frequency. The frequency mixer mixes the first and second input signals to produce a down converted signal comprising the frequency difference signal of the first and second input signals. A lowpass filter then passes the down converted signal to a frequency doubler circuit which produces a doubled frequency, down converted signal. A lowpass signal filter then passes the doubled frequency, down converted signal to an amplifier. The output of the amplifier is directed to a second frequency doubler circuit which produces a quadrupled frequency, down converted signal. That signal is then directed to a further lowpass filter which passes the quadrupled frequency, down converted signal to a further amplifier. Finally, a direct approach spectrum analyzer analyzes the amplifier output signal which is an intermediate frequency signal in the most sensitive range of the spectrum analyzer for phase noise measurements on the device under test.

Modular analyzer system

Abstract: A system of modular analyzers each adapted for independent operation and each possessing different operational characteristics adapted for particular applications. Such modular analyzers may be joined together with precise indexing means such that a single sample carousel may be accessed by fluid transfer probes from both of the analyzers to thus form a system which operates as a single analyzer of increased capacity and versatility.

Fundamental relations between the LMS algorithm and the DFT

Abstract: The digital Fourier transform (DFT) and the adaptive least mean square (LMS) algorithm have existed for some time. This paper establishes a connection between them. The result is the "LMS spectrum analyzer," a new means for the calculation of the DFT. The method uses a set of N periodic complex phasors whose frequencies are equally spaced from dc to the sampling frequency. The phasors are weighted and then are summed to generate a reconstructed signal. Weights are adapted to realize a best least squares fit between this reconstructed signal and the input signal whose spectrum is to be estimated. The magnitude squares of the weights correspond to the power spectrum. For a proper choice of adaptation speed, the LMS spectrum analyzer will provide an exact N -sample DFT. New DFT outputs will be available in steady flow after the introduction of each new data sample.

Automatic multiple-sample multiple-reagent chemical analyzer

Abstract: An analyzer for chemical assays includes a turntable (20) which supports sample containers (22) and reagent containers (24) within a cooled volume and test cells (26) about the periphery of the cooled volume. A probe (30) is carried by a rotating arm (32) for withdrawing liquid from the containers and dispensing the liquid. Fixed stations are also provided in the path of the probe. One such station (40) serves to both wash the tip of the probe and to receive samples for flow-through analysis. Heaters (44, 46) associated with the probe and with the test cells increase the rate of reaction. Curved walls of test cell segments match the optics of an optical analyzer so that light from the analyzer lamp (124) is generally orthogonal to the curved surfaces. The light voltage of the lamp may be controlled as a function of lamp wavelength required for particular assays. The system provides multiple-point calibration and automatic dilution of samples.