Topic
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.
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Patent•
10 Jul 1979
TL;DR: In this paper, the output of an oscillator under the control of the 2nd PLL circuit and by performing conversion into the 1st intermediate frequency with its output is presented, where the output is obtained by filtering at low-pass filter 9 and then supplied to and converted by frequency mixer 8 into 2nd intermediate frequency.
Abstract: PURPOSE: To constitute a receiver of superior frequency stability whose reception frequency is variable at random frequency intervals by frequency-dividing the output of an oscillator under the control of the 2nd PLL circuit and by performing conversion into the 2nd intermediate frequency with its output. CONSTITUTION: An arrival signal from antenna 1 is converted into the 1st intermediate frequency by frequency mixer 4 with the output of the 1st local oscillator 5 of the 1st PLL circuit 28, and it is applied to frequency mixer 8 by way of the 1st intermediate frequency amplifier. The output of oscillator 11 of the 2nd PLL circuit 29, on the other hand, is divided by M at frequency divider 10 and higher harmonics are extracted by filtering at low-pass filter 9 and then supplied to and converted by frequency mixer 8 into the 2nd intermediate frequency. Maximum frequency intervals at which the output of frequency divider 10 is variable are equalized to minimum frequency intervals at which the output of the 1st local oscillator 5 is variable and dividing ratios of dividing-ratio setting circuits 21 and 25 are brought under the coupling control of dividing-ratio arithmethic circuit 22. COPYRIGHT: (C)1981,JPO&Japio
17 citations
Patent•
23 Nov 1944
TL;DR: In this paper, the authors describe an electrical apparatus and particularly to an ultra high frequency oscillator whose frequency output may be varied over a limited range without substantial change in power without substantial changes in power.
Abstract: This invention relates to an electrical apparatus and particularly to an ultra high frequency oscillator whose frequency output may be varied over a limited range without substantial change in power. In systems operating at ultra-high frequency, it is customary to use cavity resonators with...
17 citations
Patent•
15 Aug 1978TL;DR: An electronic system for scanning across a range of received signals and aining a digital representation of a predetermined position, for example, the mid-point, of the received signal, without having to ascertain directly the frequency at said predetermined position as mentioned in this paper.
Abstract: An electronic system for scanning across a range of received signals and aining a digital representation of a predetermined position, for example, the mid-point, of the bandwidth of the received signal, without having to ascertain directly the frequency at said predetermined position The system can include a homodyne receiver (zero-beat reception) using a voltage controlled local oscillator or a superheterodyne receiving using a local oscillator for producing an intermediate frequency
17 citations
Patent•
23 Aug 1968TL;DR: In this article, a variable capacitor is provided in circuit with the crystal so as to correct for the crystal frequency drifts due to changes in operation of the crystal over extended periods of time.
Abstract: A crystal controlled oscillator is frequency sensitive to variations in crystal load capacitance in circuit with the crystal, to variations in temperature and to operation over extended periods of time. A variable capacitor is provided in circuit with the crystal so as to correct for the crystal frequency drifts due to changes in operation of the crystal over extended periods of time. A separate fixed capacitor is connected in series with the crystal and in circuit with the variable capacitor to provide part of the frequency determining circuit of the crystal oscillator. A temperature compensation network is coupled across the fixed capacitor and is responsive to temperature changes to provide a correct degree of load capacitance change in the circuit so that the oscillator frequency is maintained within a given frequency tolerance regardless of the adjustment of the variable capacitor which is used to adjust the crystal for frequency drift.
17 citations
Patent•
05 Jun 1974
TL;DR: In this article, the frequency of an output signal of the local oscillator is electronically varied across a frequency region which includes the preselected frequency, and a change in the oscillator signal frequency is corrected by means of an automatic frequency control feedback loop containing a discriminator circuit.
Abstract: Apparatus and method for providing an automatic frequency tuning system capable of supplying a local oscillator signal with a preselected frequency. The frequency of an output signal of the local oscillator is electronically varied across a frequency region which includes the preselected frequency. The output signal of the local oscillator is combined with the output signal of a reference signal generator. After the combination of the local oscillator signal with the reference oscillator signal produces a preestablished condition which is the result of the local oscillator signal attaining the preselected frequency, the frequency of the local oscillator signal is held constant. The local oscillator signal is thereafter compared to the reference oscillation signal and a change in the local oscillator signal frequency is corrected by means of an automatic frequency control feedback loop containing a discriminator circuit.
17 citations