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.

Frequency adaptive, power-energy re-scheduler

Abstract: A frequency adaptive, power-energy re-scheduler (FAPER) that includes a frequency transducer that notes frequency or frequency deviations of an electrical system and logic means which controls and re-schedules power flow to a load unit in part on the basis of the deviations in frequency from a nominal frequency and in part on the needs to the load unit as expressed by an external sensor signal obtained from the physical system affected by the load unit

Solar type IV burst spectral fine structures - I. Observations

Abstract: The fine structures (FS) of solar type IV radio bursts are of principal interest for flare plasma diagnostics in the low corona In this paper we give an observational (Part I) and theoretical (Paper II) treatment of broad band radio pulsations (BBP) and zebra patterns (ZP) in a well observed flaring sigmoidal loop system of AR 7792 on 25 October 1994 We present comprehensive meter-decimeter radio spectral (Astrophysical Institute Potsdam, AIP) and meter wave heliographic (Nancay Radio Heliograph of Paris-Meudon Observatory, NRH) observations Spectral and spatial properties of FS elements (one pulsation pulse, one single zebra stripe) as well as a statistical analysis for the whole fine structure event are presented The source sites are compared with soft X-ray images of the flare, and with force-free extrapolated coronal magnetic fields Both FS sources occur in a common diverging loop structure with a turning height of about 70 Mm The BBP source is shown to appear (if seen along the loop axis) nearer to the injection site of the electrons than the ZP source BBP do show high frequency drift (-250 MHz s - 1 ) At a given frequency, the projected source speed is 11 x 10 5 km s - 1 For ZP, we find a good correlation between the inclination of a single zebra stripe to the heliographic observing frequency level in the dynamic spectrogram, and the speed of the simultaneously observed projected source motion at this frequency The direction of the source motion at a given frequency is on average found to be perpendicular between BBP and ZP sources During a time interval of 90 s the BBP source consists in its lower part (higher observing frequencies) of a widely spaced double source Despite a source distance of 360 Mm both subsources are highly correlated and thus probably simultaneously driven We come to the conclusion that both fine structures are emitted during repeated electron beam injection into an asymmetric magnetic trap configuration between a footpoint in the leading spot of AR 7792 and a trailing more dispersed footpoint In Paper II we will show that the specifications derived from the data allow for selecting one out of several competing fine structure models which explains the simultaneous formation of BBP and ZP in the same loop structure

Micro-receiver for receiving a high frequency frequency-modulated or phase-modulated signal

Abstract: A micro-receiver for receiving a high frequency frequency modulated or phase modulated signal, including a single integrated circuit in BiCMOS technology and on which is integrated a high frequency amplifier, an oscillator, a modulator, an intermediate frequency filter, an intermediate frequency amplifier, a demodulator, a low pass filter and a low frequency amplifier. The integrated circuit includes in addition a muting or squelch circuit, a voltage multiplier as well as a standby circuit. The circuits working in a lower frequency range are implemented in CMOS technology, and operated in a very energy-saving way with a single-cell battery with a low battery voltage of 1.3 V. The voltage multiplier provides a higher operating voltage for the circuits working in a higher frequency range. Because of the high degree of integration made possible by implementing the intermediate frequency and low frequency circuits in CMOS technology, it is possible to dispose the receiver, including a battery and earphone, in a housing which can be inserted into the external auditory canal of a person.

Automatic pretuning of a voltage controlled oscillator in a frequency synthesizer using successive approximation

Abstract: The automatic pretuning of a voltage controlled oscillator in a phase locked loop frequency synthesizer utilizes a successive approximation technique to rapidly bring the coarse tuning voltage of the oscillator to the desired pretuning value. A digital number stored in a digital register is converted to an analog voltage value and applied to the voltage controlled oscillator as the coarse tuning voltage. The frequency of the output signal from the oscillator is compared with a reference signal, and control logic responsive to the sense of the frequency difference between the reference signal and the oscillator output signal adjusts the value of the number stored in the digital register successively from the most significant bit to the least significant bit. A microprocessor can be used to adjust the value of the number stored in the register, as well as provide additional functions such as reverse successive approximation when the synthesizer is switched from one frequency to another frequency. The microprocessor can also be used to sweep the coarse tuning voltage of the oscillator until the output signal is within the capture range of the phase locked loop, and thereafter perform a successive approximation function to bring the coarse tuning voltage to the center of the capture range.

RF signal generator

Abstract: An RF test signal generator including a driving oscillator, a pulse generr for generating narrow spikes at the oscillator frequency (such as a step recovery diode), a modulator and an attenuator. Since the very narrow pulse exhibits nearly constant amplitude in the frequency domain, a constant amplitude comb spectrum with frequency spacing at the oscillator frequency is generated so as to facilitate automated testing techniques.