Abstract The frequency of a received r-f input signal is accurately measured over a wide dynamic range synchronously detecting the signal with a superheterodyne receiver at intermediate frequency, phase locking the i-f signal to that of a reference signal, applying this reference signal to a frequency doubler whose output is applied to the modulating input of a balanced modulator energized on its carrier input by the output of another frequency doubler that doubles the frequency of the same local oscillator that is mixed with the input signal to provide the intermediate frequency signal. The output of the balanced modulator may then be applied to a tuned amplifier which provides as an output a signal of frequency exactly twice the frequency of the input signal that may then be conveniently measured, such as with a counter. The apparatus includes a phase-locked loop that adjusts the frequency of the local oscillator so that the input signal is beat down exactly to the intermediate frequency.
Inventors
👤 F Parisi
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-10-27 21:32
CPC Classifications
G; G01; G01R; G01R23/00
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
173 words
Frequency measuring apparatus comprising, an input terminal for receiving over a predetermined band of frequencies an input signal whose frequency is to be measured, a source of a local oscillator signal, means for mixing the signal on said input terminal with said local oscillator signal to provide an i-f signal of different frequency, a source of a fixed frequency reference substantially at said difference frequency, phase detecting means responsive to said i-f signal and said reference signal for providing an error signal representative of the phase difference therebetween, means for applying said error signal to said local oscillator to maintain said i-f signal substantially locked in phase to said reference signal, means for multiplying the frequencies of said local oscillator and reference signals by the same integral multiple different from one, and means for mixing the latter multiplied signals to provide a signal of frequency outside said predetermined band of frequencies that is said multiple of the frequency of the signal on said input terminal that is mixed to provide said i-f signal.
Claim 2
Dependent Claim
173 words
Frequency measuring apparatus comprising, an input terminal for receiving over a predetermined band of frequencies an input signal whose frequency is to be measured, a source of a local oscillator signal, means for mixing the signal on said input terminal with said local oscillator signal to provide an i-f signal of different frequency, a source of a fixed frequency reference substantially at said difference frequency, phase detecting means responsive to said i-f signal and said reference signal for providing an error signal representative of the phase difference therebetween, means for applying said error signal to said local oscillator to maintain said i-f signal substantially locked in phase to said reference signal, means for multiplying the frequencies of said local oscillator and reference signals by the same integral multiple different from one, and means for mixing the latter multiplied signals to provide a signal of frequency outside said predetermined band of frequencies that is said multiple of the frequency of the signal on said input terminal that is mixed to provide said i-f signal.
Claim 3
Dependent Claim
20 words
Frequency measuring apparatus in accordance with claim 1 and further comprising means for counting the frequency of the latter signal.