Patent US5086512A successfully refreshed from Google Patents.
US5086512A
Expired / Lapsed
US
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Compensation system for dynamically tracking and nulling local oscillator feedthrough
Assignee: Agilent Technologies Inc
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Filing: 1989-12-21
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Granted: 1992-02-04
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Expires: 2009-12-21
Abstract
Abstract Local oscillator feedthrough in a superheterodyne receiver is eliminated by a servo loop-controlled compensation circuit that dynamically tracks the feedthrough signal and adjusts both the phase and amplitude of a compensating signal as needed to maintain the level of the feedthrough signal below a threshold value.
Inventors
- 👤 Manfred U. Bartz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 22:37
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/06; H04B1/10; H04B1/12; H03; H03D; H03D7/00; H03D2200/00; H03D2200/0001; H03D2200/0025; H03D2200/0029; H03D2200/0041; H03D2200/0052; H03D2200/009
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
202 words
In a method of nulling local oscillator feedthrough in a superheterodyne receiver, the receiver including a mixer driven by RF input and local oscillator signals, the receiver producing a receiver signal which includes an undesirable local oscillator component, the method including summing the receiver signal with a nulling signal derived from the local oscillator signal, said nulling signal having substantially the same amplitude and opposite phase as the undesired local oscillator component, an improvement comprising the steps: (a) providing an automatic control circuit; (b) producing from the automatic control circuit a first electrical control signal on which the nulling signal depends; (c) setting the first control signal to a first value; (d) incrementing the first control signal, and thereby changing the nulling signal; (e) determining whether the undesired local oscillator component is diminished by the aforesaid incrementing of the first control signal and, if so, storing a datum indicative of the value of the first control signal in an electrical memory element; (f) repeating steps (d) and (e) until the first control signal reaches a second value; (g) recalling the stored datum from the electrical memory element; and (h) setting the first control signal to the value indicated by said stored datum.
Claim 2
Dependent Claim
202 words
In a method of nulling local oscillator feedthrough in a superheterodyne receiver, the receiver including a mixer driven by RF input and local oscillator signals, the receiver producing a receiver signal which includes an undesirable local oscillator component, the method including summing the receiver signal with a nulling signal derived from the local oscillator signal, said nulling signal having substantially the same amplitude and opposite phase as the undesired local oscillator component, an improvement comprising the steps: (a) providing an automatic control circuit; (b) producing from the automatic control circuit a first electrical control signal on which the nulling signal depends; (c) setting the first control signal to a first value; (d) incrementing the first control signal, and thereby changing the nulling signal; (e) determining whether the undesired local oscillator component is diminished by the aforesaid incrementing of the first control signal and, if so, storing a datum indicative of the value of the first control signal in an electrical memory element; (f) repeating steps (d) and (e) until the first control signal reaches a second value; (g) recalling the stored datum from the electrical memory element; and (h) setting the first control signal to the value indicated by said stored datum.
Claim 3
Dependent Claim
130 words
The method of claim 1 which further comprises: (i) providing from the automatic control circuit a second electrical control signal on which the nulling signal depends, said second control signal being different than the first; (j) setting the second control signal to a first value; (k) incrementing the second control signal; (l) determining whether the undesired local oscillator component is diminished by the aforesaid incrementing of the second control signal and, if so, storing a datum indicative of the value of the second control signal in an electrical memory element; (m) repeating steps (k) and (l) until the second control signal reaches a second value; (n) recalling the stored datum from the electrical memory element; and (o) setting the second control signal to the value indicated by said stored datum.
Claim 4
Dependent Claim
88 words
The method of claim 1 which further includes: (i) providing from the automatic control circuit a second electrical control signal on which the nulling signal depends, said second control signal being different than the first; (j) setting the second control signal to a first value; (k) incrementing the second control signal; (l) determining whether the undesired local oscillator component is diminished by the aforesaid incrementing of the second control signal and, if so, repeating steps (k) and (l) and, if not, discontinuing incrementing of the second control signal.
Claim 5
Dependent Claim
26 words
The method of claim 3 which further includes decrementing the second control signal if the undesired local oscillator component is not diminished by the incrementing step.
Claim 6
Dependent Claim
165 words
In a method of nulling local oscillator feedthrough in a superheterodyne receiver, the receiver including a mixer driven by RF input and local oscillator signals, the receiver producing a receiver signal which includes an undesirable local oscillator component, the method including summing the receiver signal with a nulling signal derived from the local oscillator signal, said nulling signal having substantially the same amplitude and opposite phase as the undesired local oscillator component, an improvement comprising the steps: (a) providing an automatic control circuit; (b) producing from the automatic control circuit a first electrical control signal on which the nulling signal depends; (c) setting the first control signal, and thereby the nulling signal, to a first value; (d) incrementing the first control signal, and thereby changing the nulling signal; (e) determining whether the undesired local oscillator component is diminished by the aforesaid incrementing of the first control signal and, if so, repeating steps (d) and (e) and, if not, discontinuing incrementing of the first control signal.
Claim 7
Dependent Claim
165 words
In a method of nulling local oscillator feedthrough in a superheterodyne receiver, the receiver including a mixer driven by RF input and local oscillator signals, the receiver producing a receiver signal which includes an undesirable local oscillator component, the method including summing the receiver signal with a nulling signal derived from the local oscillator signal, said nulling signal having substantially the same amplitude and opposite phase as the undesired local oscillator component, an improvement comprising the steps: (a) providing an automatic control circuit; (b) producing from the automatic control circuit a first electrical control signal on which the nulling signal depends; (c) setting the first control signal, and thereby the nulling signal, to a first value; (d) incrementing the first control signal, and thereby changing the nulling signal; (e) determining whether the undesired local oscillator component is diminished by the aforesaid incrementing of the first control signal and, if so, repeating steps (d) and (e) and, if not, discontinuing incrementing of the first control signal.
Claim 8
Dependent Claim
26 words
The method of claim 5 which further includes decrementing the first control signal if the undesired local oscillator component is not diminished by the incrementing step.
Claim 9
Dependent Claim
130 words
The method of claim 5 which further comprises: (i) providing from the automatic control circuit a second electrical control signal on which the nulling signal depends, said second control signal being different than the first; (j) setting the second control signal to a first value; (k) incrementing the second control signal; (l) determining whether the undesired local oscillator component is diminished by the aforesaid incrementing of the second control signal and, if so, storing a datum indicative of the value of the second control signal in an electrical memory element; (m) repeating steps (k) and (l) until the second control signal reaches a second value; (n) recalling the stored datum from the electrical memory element; and (o) setting the second control signal to the value indicated by said stored datum.
Claim 10
Dependent Claim
88 words
The method of claim 5 which further includes: (i) providing from the automatic control circuit a second electrical control signal on which the nulling signal depends, said second control signal being different than the first; (j) setting the second control signal to a first value; (k) incrementing the second control signal; (l) determining whether the undesired local oscillator component is diminished by the aforesaid incrementing of the second control signal and, if so, repeating steps (k) and (l) and, if not, discontinuing incrementing of the second control signal.
Claim 11
Dependent Claim
26 words
The method of claim 8 which further includes decrementing the second control signal if the undesired local oscillator component is not diminished by the incrementing step.
Claim 12
Dependent Claim
177 words
A signal analysis instrument comprising: means for receiving an input signal to be analyzed; a local oscillator for producing a local oscillator signal; a mixer for mixing the input signal with the local oscillator signal, said mixer producing an undesired local oscillator component in subsequent receiver signals; a feed forward circuit for introducing a compensating signal into one of said subsequent receiver signals, said compensating signal having amplitude and phase characteristics causing it to cancel the undesired signal from the subsequent receiver signal; said feed forward circuit including: first means for sampling the subsequent receiver signal to detect the magnitude of the undesired signal therein; second means for producing first and second control signals; third means responsive to the first control signal for varying the amplitude of the compensating signal; and fourth means responsive to the second control signal for varying the phase of the compensating signal; the second means further including means for automatically and iteratively changing the first and second control signals to minimize the magnitude of the undesired signal detected by the first means.
Claim 13
Dependent Claim
177 words
A signal analysis instrument comprising: means for receiving an input signal to be analyzed; a local oscillator for producing a local oscillator signal; a mixer for mixing the input signal with the local oscillator signal, said mixer producing an undesired local oscillator component in subsequent receiver signals; a feed forward circuit for introducing a compensating signal into one of said subsequent receiver signals, said compensating signal having amplitude and phase characteristics causing it to cancel the undesired signal from the subsequent receiver signal; said feed forward circuit including: first means for sampling the subsequent receiver signal to detect the magnitude of the undesired signal therein; second means for producing first and second control signals; third means responsive to the first control signal for varying the amplitude of the compensating signal; and fourth means responsive to the second control signal for varying the phase of the compensating signal; the second means further including means for automatically and iteratively changing the first and second control signals to minimize the magnitude of the undesired signal detected by the first means.
Claim 14
Dependent Claim
62 words
The signal analysis instrument of claim 10 in which: the first means includes an analog-to-digital converter for producing a digital first signal related to the magnitude of the undesired signal in the subsequent receiver signal; the second means includes means for producing first and second digital control signals, and digital-to-analog converter means for converting said digital control signals to analog control signals.
Claim 15
Dependent Claim
15 words
The signal analysis instrument of claim 11 in which the second means comprises a microprocessor.
Claim 16
Dependent Claim
16 words
The signal analysis instrument of claim 10 in which the third means includes a PIN diode.
Claim 17
Dependent Claim
16 words
The signal analysis instrument of claim 10 in which the fourth means includes a varactor diode.
Claim 18
Dependent Claim
185 words
In an apparatus for nulling local oscillator feedthrough in a superheterodyne receiver, the receiver including a mixer driven by a source of RF input signals and a source of local oscillator signals, the receiver producing a receiver signal which includes an undesirable local oscillator component, the apparatus including compensating means for summing the receiver signal in a post-mixer stage with a compensating signal derived from the local oscillator signal, said compensating signal having substantially the same amplitude and opposite phase as the undesired local oscillator component, an improvement wherein the compensating means has an input coupled to the source of local oscillator signals and an output coupled to the post-mixer stage and includes: a varactor; first means for controllably biasing the varactor to control the phase of the compensating signal; a PIN diode; second means for controllably biasing the PIN diode to control the amplitude of the compensating signal; a detector for detecting the undesired local oscillator component of the receiver signal and producing a detector signal corresponding thereto; and means for automatically controlling the first and second means in response to the detector signal.
Claim 19
Dependent Claim
185 words
In an apparatus for nulling local oscillator feedthrough in a superheterodyne receiver, the receiver including a mixer driven by a source of RF input signals and a source of local oscillator signals, the receiver producing a receiver signal which includes an undesirable local oscillator component, the apparatus including compensating means for summing the receiver signal in a post-mixer stage with a compensating signal derived from the local oscillator signal, said compensating signal having substantially the same amplitude and opposite phase as the undesired local oscillator component, an improvement wherein the compensating means has an input coupled to the source of local oscillator signals and an output coupled to the post-mixer stage and includes: a varactor; first means for controllably biasing the varactor to control the phase of the compensating signal; a PIN diode; second means for controllably biasing the PIN diode to control the amplitude of the compensating signal; a detector for detecting the undesired local oscillator component of the receiver signal and producing a detector signal corresponding thereto; and means for automatically controlling the first and second means in response to the detector signal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-02-03 | 1995-08-05 | 1996-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-02-03 | 1999-08-05 | 2000-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-02-03 | 2003-08-05 | 2004-02-04 | $7700.00 | Window Closed / Lapsed |