Spectrum analyzer

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

Methods and apparatus for time-domain measurement with a high frequency circuit analyzer

Abstract: A method of measuring the response of an electronic device to a high frequency input signal is performed with an analyzer (1) The method includes providing an electronic device (for example a transistor or amplifier) to be tested, providing a measurement system (10, 11 a , 11 b , 12, SA, SB) including a microwave transition analyzer (MTA) (10) connected to the device, applying a signal to the device and measuring with the MTA (10) the resulting incident and reflected waves at a port (3, 4) of the device, ascertaining first calibration data regarding the measurement system (10, 11 a , 11 b , 12, SA, SB), processing signals representative of the waves as measured by the MTA (10), with the use of the first calibration data, to compensate for the influence of the measurement system and the connection between the MTA (10) and the device on the waves between the port (3, 4) of the device and the MTA to produce vector corrected s-parameters, ascertaining, by measuring signals at a port of the device with a real network with known properties, second calibration data concerning voltage waveforms at the port, and processing said vectors corrected s-parameters with the use of the second calibration data to produce output signals from with the absolute values of the magnitude and phase of waves at the port of the device may be directly ascertained The method is of use in improving the efficiency and power capabilities of amplifiers for use in mobile communication base stations

Response mechanism for surface acoustic wave gas sensors based on surface-adsorption.

Abstract: A theoretical model is established to describe the response mechanism of surface acoustic wave (SAW) gas sensors based on physical adsorption on the detector surface. Wohljent's method is utilized to describe the relationship of sensor output (frequency shift of SAW oscillator) and the mass loaded on the detector surface. The Brunauer-Emmett-Teller (BET) formula and its improved form are introduced to depict the adsorption behavior of gas on the detector surface. By combining the two methods, we obtain a theoretical model for the response mechanism of SAW gas sensors. By using a commercial SAW gas chromatography (GC) analyzer, an experiment is performed to measure the frequency shifts caused by different concentration of dimethyl methylphosphonate (DMMP). The parameters in the model are given by fitting the experimental results and the theoretical curve agrees well with the experimental data.

Application of a Digital Signal Analyzer to the easurementTofF Power System Ground Impedances

Abstract: A new method is described for measuring the impedance of power system ground systems where, because of a significant reactive component or the presence of a large residual power system voltage, conventional ground resistance measuring instruments cannot be used. A white noise source together with a digital signal analyzer are used. Results of three applications are given.

A dual analyzer for real-time impedance and noise spectroscopy of nanoscale devices.

Abstract: This paper introduces a simple portable dual analyzer which allows real-time ac-impedance measurements and noise spectroscopic analysis simultaneously, employing one or two data acquisition systems together with a low noise current-to-voltage preamplifier. The input signal composed of numerous selected frequencies of sinusoidal voltages with a dc bias was applied to a device under the test (DUT): single walled carbon nanotube field effect transistors (SWCNT-FETs). Each frequency component, ranging from 1 to 46.4 kHz, was successfully mapped to a Nyquist plot using the background of the electrical noise power spectrum. It is, thus, clearly demonstrated that this dual analyzer enables the real-time ac-impedance analysis and the frequency response of the carrier transport in the SWCNT-FETs as a DUT.

Speech signal bandwidth compression and expansion apparatus, and bandwidth compressing speech signal transmission method, and reproducing method.

Abstract: A speech signal bandwidth compression and expansion apparatus and its method. On the transmitting side, system parameters are extracted from a speech signal by a linear prediction analyzer. A prediction residual signal is obtained by inverse filtering processing by using the system parameters. The prediction residual signal is lowered in sampling rate by a down-sampler and converted to a baseband signal. From the baseband signal, a time series signal is derived by a linear prediction synthesizer. Thereafter, the time series signal is converted to an analog signal and transmitted. On the receiving side, a received signal is subjected to inverse filtering processing to reproduce a baseband signal. The sampling rate of the reproduced baseband signal is raised to derive a time series signal. From the time series signal, a high frequency band component is generated. The high frequency band component is added to the baseband signal to generate an excitation signal. From the excitation signal, the original speech signal is reproduced by a linear prediction synthesizer.