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US4392233A
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US
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Method of filtering electromagnetic waves and dual channel audio code filter therefor
Assignee: Individual
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Filing: 1981-05-11
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Granted: 1983-07-05
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Expires: 2001-05-11
Abstract
Abstract An original electromagnetic continuous wave which is broken up into discrete lengths to form intelligence such as Morse Code, is filtered to eliminate noise, static and other electrical interference to render a weak code signal audible even in the worst receiving conditions. The original broken-up electromagnetic code wave is converted into corresponding discrete lengths of direct current voltage signals through the use of a phase-locked loop circuit. This D.C. voltage signal is then utilized to activate an audio oscillator and thereby generate a new coded or broken-up audio wave completely free of noise and other interference, which corresponds to the original wave being filtered. This new wave is audibly produced over a speaker and simultaneously therewith, the original wave before filtering is also audibly produced over a speaker through a second channel. This permits accurate tuning of the weak signal through the second channel and undistorted reproduction through the filtering channel. To enhance audibility of the reconstructed code signal from the filtered channel, the second channel receiving and audibly producing the unfiltered code signal may be provided with a muting circuit to mute the second channel during periods of reception of the code signal through the filtering channel in order to completely eliminate any background noise created by the second channel receiving and reproducing the unfiltered original code signal.
Inventors
- 👤 Ernest M. Laughner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 00:57
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/34; H04; H04L; H04L27/00; H04L27/02; H04L27/06
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
89 words
The method of filtering an original electromagnetic continuous wave which is broken up into discrete lengths to form intelligence comprising the steps of, converting the original broken-up electromagnetic wave into corresponding discrete lengths of a D.C. voltage signal through the use of a phase-locked loop circuit, utilizing said D.C. voltage signal to activate an audio oscillator and thereby generating a new broken-up audio wave corresponding to the original wave being filtered, audibly producing said new wave with speaker means, and simultaneously audibly producing said original wave with speaker means.
Claim 2
Independent Claim
89 words
The method of filtering an original electromagnetic continuous wave which is broken up into discrete lengths to form intelligence comprising the steps of, converting the original broken-up electromagnetic wave into corresponding discrete lengths of a D.C. voltage signal through the use of a phase-locked loop circuit, utilizing said D.C. voltage signal to activate an audio oscillator and thereby generating a new broken-up audio wave corresponding to the original wave being filtered, audibly producing said new wave with speaker means, and simultaneously audibly producing said original wave with speaker means.
Claim 3
Dependent Claim
65 words
The method of claim 1, including the step of first clipping said original wave at a predetermined level with audio limiter means to eliminate noise and signal above said predetermined level before the step of converting the original wave, and increasing the level of the original wave before clipping to a level well above said predetermined level to insure passage of even weak original signals.
Claim 4
Dependent Claim
48 words
The method of claim 2, including the step of shaping the clipped original wave with bandpass filter means which is peaked at a predetermined audio center frequency corresponding with a pre-tuned center frequency of the phase-locked loop means prior to the step of converting the original wave form.
Claim 5
Dependent Claim
25 words
The method of claim 1, including the step of muting the audible production of said original wave during periods said new wave is being generated.
Claim 6
Dependent Claim
102 words
A dual channel audio code filter for connection to the output of an audio receiver, comprising phase-locked loop circuit means for producing a D.C. signal during reception of an original electromagnetic wave to be filtered at its input from an audio receiver output, oscillator circuit means electrically connected to receive the D.C. signal and thereby operable to generate a new audio wave corresponding to the original wave to be filtered, first speaker means electrically connected to said oscillator circuit means for audibly producing said new wave, and second speaker means electrically connectable to receive and audibly produce the original unfiltered audio wave.
Claim 7
Dependent Claim
102 words
A dual channel audio code filter for connection to the output of an audio receiver, comprising phase-locked loop circuit means for producing a D.C. signal during reception of an original electromagnetic wave to be filtered at its input from an audio receiver output, oscillator circuit means electrically connected to receive the D.C. signal and thereby operable to generate a new audio wave corresponding to the original wave to be filtered, first speaker means electrically connected to said oscillator circuit means for audibly producing said new wave, and second speaker means electrically connectable to receive and audibly produce the original unfiltered audio wave.
Claim 8
Dependent Claim
56 words
The dual channel audio code filter of claim 5, including audio limiter circuit means electrically connected to said phase-locked loop circuit means to receive and clip the original wave to be filtered at a predetermined level to eliminate noise signals above said predetermined level before the original wave is received by said phase-locked loop circuit means.
Claim 9
Dependent Claim
53 words
The dual channel audio code filter of claim 6, including bandpass filter circuit means interposed and electrically connected between said audio limiter circuit means and said phase-locked loop circuit means for shaping the original wave as clipped by said audio limiter circuit means before it is received by said phase-locked loop circuit means.
Claim 10
Dependent Claim
35 words
The dual channel audio code filter of claim 7, wherein said bandpass filter circuit means is peaked at a predetermined audio center frequency corresponding with a pre-tuned center frequency of said phase-locked loop circuit means.
Claim 11
Dependent Claim
49 words
The dual channel audio code filter of claim 5, including muting circuit means electrically connected to the input of said second speaker means to mute said second speaker means during periods that said oscillator circuit means is generating a new audio wave being reproduced by the first speaker means.
Claim 12
Dependent Claim
32 words
The dual channel audio code filter of claim 5, wherein said first and second speaker means have amplifiers connected thereto with volume controls to variably amplify the waves being audibly produced respectively.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-07-04 | 1987-01-03 | 1987-07-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-07-04 | 1991-01-03 | 1991-07-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-07-04 | 1995-01-03 | 1995-07-05 | $7700.00 | Window Closed / Lapsed |