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Class Information
Number: 324/76.68
Name: Electricity: measuring and testing > Measuring, testing, or sensing electricity, per se > Frequency of cyclic current or voltage (e.g., cyclic counting etc.) > By phase comparison > With filtering
Description: Subject matter including a network of resistors, inductors, or capacitors which offers comparatively little opposition to certain frequencies, while blocking or attenuating other frequencies.
Patents under this class:
| Patent Number |
Title Of Patent |
Date Issued |
| 7411463 |
Method, system, apparatus, and program for measuring the damping factor of an Nth order phase locked loop (PLL) |
Aug. 12, 2008 |
| 7257497 |
Sequential frequency band acquisition apparatus for test and measurement instruments |
Aug. 14, 2007 |
| 6742153 |
Test configuration and method for testing a digital electronic filter |
May. 25, 2004 |
| 6577990 |
Method for determining launch system velocity, acceleration and displacement certification parameters |
Jun. 10, 2003 |
| 6320392 |
Active filter device |
Nov. 20, 2001 |
| 5832413 |
Generator protection system and method for phasor estimation and frequency tracking during frequency ramping |
Nov. 3, 1998 |
| 5714877 |
Apparatus for detecting the amplitude and phase of an A.C. signal |
Feb. 3, 1998 |
| 4914600 |
Programmable frequency identifier circuit |
Apr. 3, 1990 |
| 4914380 |
Signal receiving arrangement |
Apr. 3, 1990 |
| 4866260 |
Method and means for measuring the frequency of a periodic signal |
Sep. 12, 1989 |
| 4864221 |
Filter, phase-measuring device and method for application of said filter |
Sep. 5, 1989 |
| 4859934 |
Apparatus for measuring the frequency of microwave signals |
Aug. 22, 1989 |
| 4859933 |
Narrowband signal recognition for EMI measurement |
Aug. 22, 1989 |
| 4812743 |
Method and apparatus for detecting a narrowband signal |
Mar. 14, 1989 |
| 4810960 |
Measuring adjacent channel power |
Mar. 7, 1989 |
| 4805125 |
Apparatus and methods for improving uniformity measurements |
Feb. 14, 1989 |
| 4792932 |
Time measurement in automatic test equipment |
Dec. 20, 1988 |
| 4786168 |
Frequency domain laser velocimeter signal processor |
Nov. 22, 1988 |
| 4759069 |
Emergency signal warning system |
Jul. 19, 1988 |
| 4757253 |
Circuit arrangement for frequency analysis of received signals which lie in a wide overall frequency band |
Jul. 12, 1988 |
| 4710702 |
Heterodyne type signal-measuring method and a measuring apparatus including automatic detuning correction means |
Dec. 1, 1987 |
| 4707653 |
Frequency measurement circuit |
Nov. 17, 1987 |
| 4694263 |
Frequency modulation monitor circuit and method |
Sep. 15, 1987 |
| 4667151 |
Calibrated radio frequency sweep |
May. 19, 1987 |
| 4661769 |
Measurement of magnitude and phase angle of voltage and current phasors and frequency deviation in power systems |
Apr. 28, 1987 |
| 4640134 |
Apparatus and method for analyzing acoustical signals |
Feb. 3, 1987 |
| 4599567 |
Signal representation generator |
Jul. 8, 1986 |
| 4563638 |
Time selective frequency detection by time selective channel to channel energy comparison |
Jan. 7, 1986 |
| 4535286 |
Radio frequency receiver |
Aug. 13, 1985 |
| 4485448 |
Apparatus and method for detecting the onset of a frequency shift keyed signal |
Nov. 27, 1984 |
| 4467277 |
Programmable detector for tone signals |
Aug. 21, 1984 |
| 4459542 |
Spectrum analyzer having common two-channel filters, especially for voice recognition |
Jul. 10, 1984 |
| 4443757 |
Multiplexed electrical signal processor |
Apr. 17, 1984 |
| 4423519 |
Apparatus and method for detecting the onset of a frequency shift keyed signal |
Dec. 27, 1983 |
| 4414517 |
Non-ringing phase responsive detector |
Nov. 8, 1983 |
| 4399408 |
Apparatus for testing the linearity of a frequency modulated oscillator |
Aug. 16, 1983 |
| 4390838 |
Broadband measurement system |
Jun. 28, 1983 |
| 4380732 |
Signal spectrum display apparatus |
Apr. 19, 1983 |
| 4377961 |
Fundamental frequency extracting system |
Mar. 29, 1983 |
| 4361804 |
Electrical test instruments |
Nov. 30, 1982 |
| 4345206 |
Frequency and frequency error counting in test apparatus |
Aug. 17, 1982 |
| 4339711 |
Spectrum displaying apparatus for multichannel signals |
Jul. 13, 1982 |
| 4331882 |
Method and means for detecting spurious electrical signals in an electrical power system |
May. 25, 1982 |
| RE30949 |
Digital frequency display device |
May. 25, 1982 |
| 4307340 |
Spectrum display apparatus |
Dec. 22, 1981 |
| 4280387 |
Frequency following circuit |
Jul. 28, 1981 |
| 4270215 |
Channel indicator |
May. 26, 1981 |
| 4215280 |
Phase responsive frequency detector |
Jul. 29, 1980 |
| 4194206 |
Instantaneous frequency measurement (IFM) receiver with capability to separate cw and pulsed signals |
Mar. 18, 1980 |
| 4160212 |
Radio frequency receiver having serially coupled heterodyning stages, each stage having filters with difference center frequencies |
Jul. 3, 1979 |
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