US3716791A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flag alarm system applicable to a vor receiver
Assignee: Trane US Inc
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Filing: 1970-07-24
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Granted: 1973-02-13
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Expires: 1990-07-24
Abstract
Abstract A flag alarm system for a VOR receiver (applicable to other purposes) in which two 30 Hz signals of relatively variable phase normally present in two channels of the receiver, while the latter is operating properly, are multiplied together to produce modulation products including a dc component having a value which is a function of said phase, and which in one form of the invention is employed in a servo loop which indicates or controls said phase, and also a double frequency signal of peak amplitude independent of phase difference but a function of the products of the amplitudes of the 30 Hz signals. The double frequency signal operates to hold a flag inoperative, but cannot hold the flag if either or both 30 Hz signals disappear or are radically reduced in amplitude. The system indicates the presence or absence of valid signals, i.e. the two 30 Hz signals, and overall system malfunction, on a fail-safe basis.
Inventors
- 👤 J Flentie
- 👤 W Harries
- 👤 G Asnani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 14:24
CPC Classifications
G; G01; G01S; G01S1/00; G01S1/02; G01S1/022; G01S1/026
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
196 words
A system for detecting improper operation of a navigational system requiring two signals for its correct operation, wherein said signals are of the same frequency and of variable phase separation, said system comprising: means for heterodyning said two signals to produce in a single signal channel heterodyne products of said two signals including a dc signal of sign and amplitude which are a function of said phase separation, and at least one heterodyne product of finite frequency different from the frequency of said two signals; means for detecting and indicating the presence of said one heterodyne product at the output of said channel, including a flag alarm meter subject to a bias into one condition and responsive to at least a predetermined level of said one heterodyne product to overcome said bias and assume an alternative condition; bearing determination means connected to the output of said channel for responding to changes in the sign and amplitude of said dc signal; and means in said channel responsive to a predetermined amplitude of said dc signal for reducing the level of said one heterodyne product below said predetermined level to cause said meter to assume said one condition.
Claim 2
Independent Claim
196 words
A system for detecting improper operation of a navigational system requiring two signals for its correct operation, wherein said signals are of the same frequency and of variable phase separation, said system comprising: means for heterodyning said two signals to produce in a single signal channel heterodyne products of said two signals including a dc signal of sign and amplitude which are a function of said phase separation, and at least one heterodyne product of finite frequency different from the frequency of said two signals; means for detecting and indicating the presence of said one heterodyne product at the output of said channel, including a flag alarm meter subject to a bias into one condition and responsive to at least a predetermined level of said one heterodyne product to overcome said bias and assume an alternative condition; bearing determination means connected to the output of said channel for responding to changes in the sign and amplitude of said dc signal; and means in said channel responsive to a predetermined amplitude of said dc signal for reducing the level of said one heterodyne product below said predetermined level to cause said meter to assume said one condition.
Claim 3
Independent Claim
196 words
A system for detecting improper operation of a navigational system requiring two signals for its correct operation, wherein said signals are of the same frequency and of variable phase separation, said system comprising: means for heterodyning said two signals to produce in a single signal channel heterodyne products of said two signals including a dc signal of sign and amplitude which are a function of said phase separation, and at least one heterodyne product of finite frequency different from the frequency of said two signals; means for detecting and indicating the presence of said one heterodyne product at the output of said channel, including a flag alarm meter subject to a bias into one condition and responsive to at least a predetermined level of said one heterodyne product to overcome said bias and assume an alternative condition; bearing determination means connected to the output of said channel for responding to changes in the sign and amplitude of said dc signal; and means in said channel responsive to a predetermined amplitude of said dc signal for reducing the level of said one heterodyne product below said predetermined level to cause said meter to assume said one condition.
Claim 4
Independent Claim
196 words
A system for detecting improper operation of a navigational system requiring two signals for its correct operation, wherein said signals are of the same frequency and of variable phase separation, said system comprising: means for heterodyning said two signals to produce in a single signal channel heterodyne products of said two signals including a dc signal of sign and amplitude which are a function of said phase separation, and at least one heterodyne product of finite frequency different from the frequency of said two signals; means for detecting and indicating the presence of said one heterodyne product at the output of said channel, including a flag alarm meter subject to a bias into one condition and responsive to at least a predetermined level of said one heterodyne product to overcome said bias and assume an alternative condition; bearing determination means connected to the output of said channel for responding to changes in the sign and amplitude of said dc signal; and means in said channel responsive to a predetermined amplitude of said dc signal for reducing the level of said one heterodyne product below said predetermined level to cause said meter to assume said one condition.
Claim 5
Dependent Claim
30 words
The combination according to claim 1, wherein said bearing determination means includes a reversible rotatable motor, and means responsive to rotation of said reversible motor for reducing said phase separation.
Claim 6
Dependent Claim
203 words
Apparatus for detecting improper operation of a navigational system requiring two signals for correct operation, wherein said signals are of the same frequency and of variable phase separation, said apparatus comprising: means for combining said two signals to produce modulation products including a dc signal having an amplitude which is a function of said phase separation, and an oscillatory signal of a frequency different from the frequency of said two signals and indicative of the existence of both; alarm means for detecting the presence of said oscillatory signal delivered by said combining means, and indicating a nonalarm condition as long as said oscillatory signal has an amplitude of at least a predetermined minimum level and an alarm condition if the amplitude of said oscillatory signal falls below said minimum level; bearing determination means coupled with said combining means for responding to changes in the amplitude of said dc signal; and means interposed between said combining means and said alarm means and responsive to a predetermined amplitude of said DC signal for reducing the amplitude of said oscillatory signal below said minimum level, whereby the alarm means also indicates an alarm condition if the phase separation of said two signals reaches a predetermined magnitude.
Claim 7
Dependent Claim
203 words
Apparatus for detecting improper operation of a navigational system requiring two signals for correct operation, wherein said signals are of the same frequency and of variable phase separation, said apparatus comprising: means for combining said two signals to produce modulation products including a dc signal having an amplitude which is a function of said phase separation, and an oscillatory signal of a frequency different from the frequency of said two signals and indicative of the existence of both; alarm means for detecting the presence of said oscillatory signal delivered by said combining means, and indicating a nonalarm condition as long as said oscillatory signal has an amplitude of at least a predetermined minimum level and an alarm condition if the amplitude of said oscillatory signal falls below said minimum level; bearing determination means coupled with said combining means for responding to changes in the amplitude of said dc signal; and means interposed between said combining means and said alarm means and responsive to a predetermined amplitude of said DC signal for reducing the amplitude of said oscillatory signal below said minimum level, whereby the alarm means also indicates an alarm condition if the phase separation of said two signals reaches a predetermined magnitude.
Claim 8
Dependent Claim
145 words
In a servo system for maintaining two oscillatory signals in phase: means for combining said signals to produce modulation products including a dc signal having a magnitude which is a function of the phase difference between said two signals, and an ac signal having a frequency equal to the sum of the frequencies of said two signals and a peak amplitude independent of said phase difference; means for varying the relative phase of said two signals; means including a servo-loop responsive to said dc signal for automatically controlling said phase varying means to correct said relative phase to zero phase difference; alarm means presenting a flag indication in response to reduction of said pEak amplitude below a predetermined value; and means responsive to said dc signal for reducing the amplitude of said ac signal if the magnitude of said dc signal reaches a predetermined level.
Claim 9
Dependent Claim
145 words
In a servo system for maintaining two oscillatory signals in phase: means for combining said signals to produce modulation products including a dc signal having a magnitude which is a function of the phase difference between said two signals, and an ac signal having a frequency equal to the sum of the frequencies of said two signals and a peak amplitude independent of said phase difference; means for varying the relative phase of said two signals; means including a servo-loop responsive to said dc signal for automatically controlling said phase varying means to correct said relative phase to zero phase difference; alarm means presenting a flag indication in response to reduction of said pEak amplitude below a predetermined value; and means responsive to said dc signal for reducing the amplitude of said ac signal if the magnitude of said dc signal reaches a predetermined level.
References Cited (Backward Citations)
US3382498A
Cited
US3470557A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-13 | 1976-08-14 | 1977-02-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-13 | 1980-08-14 | 1981-02-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-13 | 1984-08-14 | 1985-02-13 | $7700.00 | Window Closed / Lapsed |