Patent US4601062A successfully refreshed from Google Patents.
US4601062A
Expired / Lapsed
US
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Tracking image frequency trap
Assignee: RCA Licensing Corp
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Filing: 1985-02-28
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Granted: 1986-07-15
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Expires: 2005-02-28
Abstract
Abstract In a superheterodyne receiver, such as a typical television receiver, a radio frequency coupling arrangement includes a first resonant circuit coupled to receive the input signal and further coupled to a second resonant circuit by a first coupling. Both resonant circuits are tuned to the desired signal frequency. The capacitive branch of the first resonant circuit includes a circuit impedance for providing a neutralizing voltage, at least a portion of which is coupled by a second coupling to the inductive branch of the second resonant circuit. The circuit impedance is selected to cause cancellation in the inductive branch between image frequency components coupled by the first coupling and image frequency components coupled by the second coupling, without substantially affecting the desired signals.
Inventors
- 👤 James Hettiger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:09
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/44; H04N5/50; H03; H03J; H03J3/00; H03J3/24; H03J3/26; H04B; H04B1/00; H04B1/06; H04B1/16; H04B1/18; H04B1/20
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
122 words
In a superheterodyne radio frequency (RF) receiver having an RF signal input port and exhibiting an undesired image frequency response when tuned to a desired signal frequency, an RF coupling arrangement comprising: first and second resonant circuit means each comprising respective parallel-connected capacitive and inductive branches, said first resonant circuit means being coupled to said input port for receiving a signal at said input port; first coupling means for mutually coupling said first and second resonant circuit means; impedance means coupled in series with said capacitive branch of said first resonant circuit means for providing a neutralizing signal; and second coupling means for coupling at least a portion of said neutralizing signal into said inductive branch of said second resonant circuit means.
Claim 2
Dependent Claim
122 words
In a superheterodyne radio frequency (RF) receiver having an RF signal input port and exhibiting an undesired image frequency response when tuned to a desired signal frequency, an RF coupling arrangement comprising: first and second resonant circuit means each comprising respective parallel-connected capacitive and inductive branches, said first resonant circuit means being coupled to said input port for receiving a signal at said input port; first coupling means for mutually coupling said first and second resonant circuit means; impedance means coupled in series with said capacitive branch of said first resonant circuit means for providing a neutralizing signal; and second coupling means for coupling at least a portion of said neutralizing signal into said inductive branch of said second resonant circuit means.
Claim 3
Dependent Claim
24 words
The RF coupling arrangement recited in claim 1 wherein said first and second resonant circuit means are resonant substantially at said desired signal frequency.
Claim 4
Dependent Claim
68 words
The RF coupling arrangement recited in claim 2 wherein said impedance means is selected to exhibit a frequency characteristic such that substantial cancellation occurs over a predetermined range of said image frequency in said inductive branch of said second resonant circuit means between image frequency components of a signal coupled by way of said first coupling means and image frequency components of said portion of said neutralizing signal.
Claim 5
Dependent Claim
59 words
The RF coupling arrangement recited in claim 3 wherein cancellation in said inductive branch of said second resonant circuit means of desired signal frequency components of a signal coupled by way of said first coupling means and desired signal frequency components of said portion of said neutralizing signal in substantially less than said cancellation between said image frequency components.
Claim 6
Dependent Claim
24 words
The RF coupling arrangement recited in claim 4 wherein the frequency separation between said desired signal frequency and said image frequency is substantially constant.
Claim 7
Dependent Claim
23 words
The RF coupling arrangement recited in claim 2 wherein said impedance means comprises a third resonant circuit for providing said neutralizing signal thereacross.
Claim 8
Dependent Claim
23 words
The RF coupling arrangement recited in claim 6, wherein said third resonant circuit comprises a parallel connection of an inductance and a capacitance.
Claim 9
Dependent Claim
31 words
The RF coupling arrangement recited in claim 7 wherein said second coupling means comprises a connection between said third resonant circuit and said inductive branch of said second resonant circuit means.
Claim 10
Dependent Claim
65 words
The RF coupling arrangement recited in claim 8 wherein the resonant frequency of said third resonant circuit is selected for causing over a predetermined range of frequency substantial cancellation in said inductive branch of said second resonant circuit means between image frequency components of a signal coupled by way of said first coupling means and image frequency components of said portion of said neutralizing signal.
Claim 11
Dependent Claim
58 words
The RF coupling arrangement recited in claim 9 wherein cancellation in said inductive branch of said second resonant circuit means of desired signal frequency components of a signal coupled by way of said first coupling means and desired signal frequency components of said portion of said neutralizing signal is substantially less than said cancellation at said image frequency.
Claim 12
Dependent Claim
35 words
The RF coupling arrangement recited in claim 10 wherein the frequency difference between said image frequency and said desired signal frequency is substantially independent of said desired signal frequency over a predetermined range of frequency.
Claim 13
Dependent Claim
19 words
The RF coupling arrangement recited in claim 11 wherein said image frequency is higher than said desired signal frequency.
Claim 14
Dependent Claim
17 words
The RF coupling arrangement recited in claim 7 wherein said second coupling means comprises a voltage divider.
Claim 15
Dependent Claim
65 words
The RF coupling arrangement recited in claim 13 wherein the resonant frequency of said third resonant circuit is selected for causing over a predetermined range of frequency substantial cancellation in said inductive branch of said second resonant circuit means between image frequency components of a signal coupled by way of said first coupling means and image frequency components of said portion of said neutralizing signal.
Claim 16
Dependent Claim
58 words
The RF coupling arrangement recited in claim 14 wherein cancellation in said inductive branch of said second resonant circuit means of desired signal frequency components of a signal coupled by way of said first cuopling means and desired signal frequency components of said portion of said neutralizing signal is substantially less than said cancellation at said image frequency.
Claim 17
Dependent Claim
35 words
The RF coupling arrangement recited in claim 15 wherein the frequency difference between said image frequency and said desired signal frequency is substantially independent of said desired signal frequency over a predetermined range of frequency.
Claim 18
Dependent Claim
19 words
The RF coupling arrangement recited in claim 16 wherein said image frequency is higher than said desired signal frequency.
Claim 19
Dependent Claim
68 words
The RF coupling arrangement recited in claim 2 wherein said impedance means is selected to exhibit a frequency characteristic such that substantial cancellation occurs in said inductive branch of said second resonant circuit means between components of said portion of said neutralizing signal having a frequency substantially equal to a predetermined trap frequency and trap frequency components of a signal coupled by way of said first coupling means.
Claim 20
Dependent Claim
58 words
The RF coupling arrangement recited in claim 18 wherein cancellation in said inductive branch of said second resonant circuit means of desired signal frequency components of said portion of said neutralizing signal and desired frequency components of a signal coupled by way of said first coupling means is substantially less than said cancellation between said trap frequency components.
Claim 21
Dependent Claim
24 words
The RF coupling arrangement recited in claim 19 wherein the frequency separation between said trap frequency and said desired signal frequency is substantially constant.
Claim 22
Dependent Claim
19 words
The RF coupling arrangement recited in claim 20 wherein said trap frequency is substantially equal to said image frequency.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1989-07-14 | 1990-01-13 | 1990-07-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-07-14 | 1994-01-13 | 1994-07-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-07-14 | 1998-01-13 | 1998-07-15 | $7700.00 | Window Closed / Lapsed |