Frequency drift

About: Frequency drift is a research topic. Over the lifetime, 5054 publications have been published within this topic receiving 56191 citations. The topic is also known as: chirp rate.

Adaptive IIR multitone detector

Abstract: An adaptive Infinite Impulse Response (IIR) filter is provided that can adaptively detect the presence of one or more tones in its input stream. The tones to be detected may be of arbitrary frequency, subject only to a limitation that such tones fall within a frequency band consistent with accepted sampling principles (e.g., a maximum frequency of interest no greater than one-half the sampling frequency--Nyquist sampling criteria). An IIR filter developed according to the method of the invention will adaptively locate the frequencies of tones to be detected, thereby allowing for frequency drift from nominal expected frequency values with no loss in accuracy. Such a filter will also process the input signal sample-by-sample, thereby avoiding the blocking problem of FFT-based filter approaches. With the filter of the invention, an application can identify the frequencies, associated power levels, SNR and duration of the tones. Thus, such an application can use a simple user specified library of tone parameters to decide if tones of interest are present in the input stream.

A Recent Development in Vacuum Tube Oscillator Circuits

Abstract: A constant frequency oscillator, which depends for its operation upon the use of electron coupling between the oscillation generating portion of the circuit and the work circuit, is described. This form of coupling is employed to isolate the work circuit from the frequency determining portion of the system. The oscillator is of the two-anode type (UX-865) and it is shown that by suitable choice of anode voltages, compensating effects may be obtained whereby changes in generator voltage may be made to have a negligible effect upon the frequency of oscillation.

Parameter Optimization of Active Frequency Drift Islanding Detection Method

Abstract: Anti-islanding protection is mandatory feature for grid-connected inverters. Desired islanding detection method not only can detect islanding within acceptable duration,but also require it has less adverse impact on power quality. The performance of islanding detection method is usually subject to anti-islanding strategy and parameter setting. The paper analyzes non detection zone(NDZ) of active frequency drift(AFD) and active frequency drift with positive feedback(AFDPF) . Based on analysis the relationship between NDZ and feedback gain of AFDPF is deduced,which can be expressed as a mathematics equation and gives range for feedback gain to guarantee anti-islanding protection. The calculation is simple and accurate,thus can be taken as a good guideline in AFDPF parameters setting.

Radio receiver with a high speed and accurate search operation and method thereof

Abstract: A controller shifts the frequency of the local oscillator with a frequency shift circuit so that as many channels to be scanned as possible will be included within specified bandwidths, detects a desired received signal by scanning each of the specified bandwidths with the shifted frequency, scans each channel within the bandwidth where the desired received signal was detected, and changes the frequency of the local oscillator or shifts the frequency of the local oscillator with the frequency shift circuit so that the desired channel frequency identified above will be at the center of said bandwidth.

Method for acquisition of gps signals and gps receiver with sample time error and frequency offset compensation

Abstract: Embodiments of a method for acquisition of GPS signals and a GPS receiver with sample time error and frequency offset compensation are generally described herein. Other embodiments may be described and claimed. In some embodiments, GPS signals are resampled at a plurality of sample rates for each of a plurality of predetermined frequency offsets to compensate for sample time error and frequency offset of a crystal oscillator. The resampled GPS signals may be cross correlated for each of the predetermined frequency offsets. In some embodiments, the sample time error and the frequency offset of the crystal oscillator may substantially exceed a time and frequency drift of reference clocks on GPS satellites.