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.

Television receiver for terrestrial broadcasting

Abstract: In a television receiver in which image frequency signals for desired signals are removed when television broadcasting signals are frequency-converted through a local oscillator and mixers, the local oscillator generates biaxial orthogonal signals to be frequency-converted by respective mixers, an output signal of one mixer being phase-shifted to be added to an output signal of the other mixer so as to thereby offset only the image frequency signals. The local oscillator and a phase shifter operate so as to follow the frequency change of the intermediate frequency signal so as to thereby stabilize the suppression of the image frequency signal.

Automatic frequency control in the presence of data

Abstract: OF THE DISCLOSURE There is provided a method of and apparatus for Automatic Frequency Control (AFC) in the presence of data. It comprises removing the effects of data modulated onto the carrier, detecting the frequency difference between the carrier frequency and the phase of the reference oscillator, and adjusting the frequency of the reference oscillator to eliminate the frequency difference. It is further characterized by digitizing the modulated carrier in quadrature, sampling the modulated carrier in quadrature at a multiple of the modulated bit rate, rotating phases toward arctangent (I/Q)=0 to remove the effects of quadrature data (I/Q) modulated onto the carrier, detecting the frequency difference between the carrier frequency and the frequency of a Voltage Controlled type of reference oscillator with a phase trajectory estimator, adjusting the frequency of the reference oscillator by the frequency difference, and establishing and generating the requisite correction voltage for a Voltage Controlled type of reference oscillator (VCO) with the phase trajectory estimator.

Analog phase tracker

Abstract: An analog phase tracker includes a phase tracking loop comprising a phase detector, a voltage controlled oscillator, a plurality of dividers and at least one multiplier for altering the phase of the voltage controlled oscillator output solely by dividing the oscillator output phase by the product of all of the dividers, while altering the frequency of the voltage controlled oscillator output by both dividing the frequency by the product of the divisors and multiplying the frequency by an integer equal to at least one of the divisors such that the frequency and phase of a signal derived by the dividers and multipliers is substantially the same as an applied periodic signal whose repetition rate may be any one of plurality of predetermined values.

Near-integer channel spur mitigation in a phase-locked loop

Abstract: A method includes relocating, to a frequency outside a cut-off frequency of a phase-locked loop, a spur frequency component at an input of the phase-locked loop coupled thereto due to an interference of a divided frequency component of an output frequency of the phase-locked loop with a reference clock frequency input thereto through a feedback path thereof when there is a near-integer relationship between the reference clock frequency input and the output frequency. The method also includes filtering the spur frequency component through the phase-locked loop.

Methods and apparatus to control frequency offsets in digitally controlled crystal oscillators

Abstract: Methods and systems of adjusting an oscillator frequency are disclosed. One example method includes reading a temperature associated with an oscillator, reading a first tuning code associated with the temperature from a memory, and tuning the oscillator with the first tuning code. The example method may further include determining a second tuning code, and storing the second tuning code and an indication of the temperature in the memory.