US3876945A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fm-receiver having means for interference suppression
Assignee: US Philips Corp
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Filing: 1973-06-01
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Granted: 1975-04-08
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Expires: 1993-06-01
Abstract
Abstract In frequency-modulated signals, particularly in the frequencyanalog measuring technique, only the zero crossings of the signals or the intervals between the zero crossings are evaluated. In order to prevent or at least to reduce interferences which occur meanwhile, the receiver is blocked for a given period after each zero crossing. In order to generate a blocking signal having an optimum duration, the values of the duration of the preceding signal zero crossing intervals are stored individually and the minimum duration to be expected of the next signal zero crossing interval is calculated therefrom. In the same manner the maximum duration to be expected of the next signal zero crossing interval can be determined, at the end of which maximum duration a substitution signal can be applied to the receiver when no zero crossing of the input signal has meanwhile been detected. As a result, the adverse effects of for instance short transmission interruptions can be eliminated.
Inventors
- 👤 Dieter Gossel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 21:55
CPC Classifications
H; H03; H03D; H03D3/00; H03D3/02; H03D3/04
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
125 words
A receiver for signals modulated in frequency by a modulating signal, comprising means for blocking said receiver during part of each time interval between successive zero crossings of said modulated signals in accordance with said modulating signal, characterized in that said blocking means comprise means for measuring the discrete duration of said zero crossing time intervals and producing a measuring signal representation of said duration, means for storing said measuring signal, means for calculating the expected value of the minimum duration of the next one of said zero crossing time intervals from said stored measuring signal and predetermined modulation data of said modulated signals, and means for producing a blocking signal having a duration substantially equal to said calculated expected value of the minimum duration.
Claim 2
Dependent Claim
125 words
A receiver for signals modulated in frequency by a modulating signal, comprising means for blocking said receiver during part of each time interval between successive zero crossings of said modulated signals in accordance with said modulating signal, characterized in that said blocking means comprise means for measuring the discrete duration of said zero crossing time intervals and producing a measuring signal representation of said duration, means for storing said measuring signal, means for calculating the expected value of the minimum duration of the next one of said zero crossing time intervals from said stored measuring signal and predetermined modulation data of said modulated signals, and means for producing a blocking signal having a duration substantially equal to said calculated expected value of the minimum duration.
Claim 3
Dependent Claim
43 words
A receiver as claimed in claim 1, characterized in that said calculating means are arranged for calculating said expected value of the minimum duration from said predetermined modulation data and only the stored measuring signal of the last preceding zero crossing time interval.
Claim 4
Dependent Claim
82 words
A receiver as claimed in claim 1, characterized in that said blocking means comprise additional means for calculating the expected value of the maximum duration of the next one of said zero crossing time intervals from said stored measuring signal and said predetermined modulation data, and means for producing a substitution receiver input signal in response to the absence of a next zero crossing of said modulated signals during a time interval equal to said calculated expected value of the maximum duration.
Claim 5
Dependent Claim
88 words
A receiver as claimed in claim 1, characterized in that said means for producing a blocking signal comprise a source of auxiliary signals, means for varying the frequency of said auxiliary signals in accordance with said calculated expected value of the minimum duration, a mixer circuit having inputs for receiving said modulated signals and said auxiliary signals, respectively, to produce an output signal having a frequency equal to the sum of the mixer input signal frequencies, and means for deriving said blocking signal from said mixer output signal.
Claim 6
Dependent Claim
85 words
A receiver as claimed in claim 3, characterized in that substitution signal producing means comprise a source of auxiliary signals, means for varying the frequency of said auxiliary signals in accordance with said calculated expected value of the maximum duration, a mixer circuit having inputs for receiving said modulated signals and said auxiliary signals, respectively, to produce an output signal having a frequency equal to the difference of the mixer input signal frequencies, and means for deriving said substitution signal from said mixer output signal.
References Cited (Backward Citations)
US3375445A
Cited
US3678396A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-07 | 1978-10-07 | 1979-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-07 | 1982-10-07 | 1983-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-07 | 1986-10-07 | 1987-04-08 | $7700.00 | Window Closed / Lapsed |