US3705403A
Expired / Lapsed
US
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Receivers for phase comparison radio navigation systems
Assignee: Decca Ltd
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Filing: 1970-11-09
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Granted: 1972-12-05
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Expires: 1990-11-09
Abstract
Abstract In a receiver for a phase comparison radio navigation system, signals of the fifth, sixth, eighth and ninth harmonics of a fundamental are received from different spaced transmitting stations and compared in phase in pairs at their least common multiple frequencies and in which a phase comparison is made between signals from the same pairs of stations at the fundamental frequency to obtain coarser but less ambiguous positional information, the fundamental frequency comparisons are effected digitally measuring the time intervals corresponding to the phase relationships. These time intervals are measured using divided down frequencies from a single clock source, the clock frequency division factors being different for the different pairs of stations so that the counts are proportional to the least common multiple frequencies.
Inventors
- 👤 David Geoffrey Hughes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 04:45
CPC Classifications
G; G01; G01S; G01S1/00; G01S1/02; G01S1/08; G01S1/20; G01S1/30; G01S1/306
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
194 words
In a receiver for a phase comparison radio navigation system of the kind in which radio frequency signals of three or more different but harmonically related frequencies received from different spaced transmitting stations are compared in phase in pairs at their least common multiple frequencies to provide positiOnal information with respect to fine patterns and in which coarser positional information to identify the lanes of the fine pattern is oBtained by making phase comparisons at the fundamental frequency for each pair of stations; the improvement comprising the provision of digital phase comparison means for the fundamental frequency comparisons, which phase comparison means comprise a clock source, an adjustable divider dividing down the clock pulse frequency, a counter to count pulses from a said divider during a time interval representative of the phase difference between the signals to be compared, and means controlling the divider in accordance with the sequential comparison of signals from different pairs of stations whereby the counter displays counts related to the phase difference, the respective counts, by the controlled adjustment of the divider, being proportional to the respective least common multiple frequencies used for the fine pattern of each pair.
Claim 2
Dependent Claim
194 words
In a receiver for a phase comparison radio navigation system of the kind in which radio frequency signals of three or more different but harmonically related frequencies received from different spaced transmitting stations are compared in phase in pairs at their least common multiple frequencies to provide positiOnal information with respect to fine patterns and in which coarser positional information to identify the lanes of the fine pattern is oBtained by making phase comparisons at the fundamental frequency for each pair of stations; the improvement comprising the provision of digital phase comparison means for the fundamental frequency comparisons, which phase comparison means comprise a clock source, an adjustable divider dividing down the clock pulse frequency, a counter to count pulses from a said divider during a time interval representative of the phase difference between the signals to be compared, and means controlling the divider in accordance with the sequential comparison of signals from different pairs of stations whereby the counter displays counts related to the phase difference, the respective counts, by the controlled adjustment of the divider, being proportional to the respective least common multiple frequencies used for the fine pattern of each pair.
Claim 3
Dependent Claim
37 words
A receiver as claimed in claim 1 wherein each phase difference between the fundamental frequency signals is measured by using the two signals to be compared in phase to gate a clock output at the appropriate frequency.
Claim 4
Dependent Claim
69 words
A receiver as claimed in claim 1 wherein each phase difference between the fundamental frequency signals is measured by measuring the corresponding time difference into a first store using a fixed clock frequency and then counting a fixed clock frequency (not necessarily the same as the aforementioned fixed clock frequency) into a display store from a period determined by the time required to count using a divided clock frequency.
Claim 5
Dependent Claim
202 words
A receiver as claimed in claim 1 wherein said clock pulse source has a frequency which is a multiple of the fundamental frequency, and wherein said adjustable divider for dividing down the frequency of the clock pulse source, said division being by selectable factors in the same ratio to one another as the aforesaid least common multiple frequencies, and wherein there are provided a store register and a display register said store register having a capacity equal to the number of clock pulses in one cycle of the fundamental frequency, means for feeding into said store register a number of clock pulses equal to the complement of the number occurring in the time interval corresponding to the phase difference between fundamental frequency signals derived from two multipulse signals received from different stations, means for filling said store register with pulses from said divider with the divider set with a division factor corresponding to the least common multiple frequency for the pair of stations from which signals are being compared and gate means controlled by said store register for gating into said display register further clock controlled pulses for a time period equal to the time period taken to fill the display register.
Claim 6
Dependent Claim
91 words
A receiver as claimed in claim 4 and for use with a transmitting system in which a master station radiates normally on the sixth harmonic of a radiation fundamental frequency and three slaves radiate normally on the fifth, eighth and ninth harmonics and wherein in the receiver, oscillators are provided at frequencies 6F, 5F, 8F and 9F locked respectively to the received signals during the normal transmission periods and wherein the clock pulse frequency is 300F and wherein said divider divides the clock frequency by factors of 10, 8 and 6.
Claim 7
Dependent Claim
20 words
A receiver as claimed in claim 5 wherein the clock pulses fed into said display register have a frequency 30F.
Claim 8
Dependent Claim
115 words
A receiver as claimed in claim 1 wherein the fine positional information is indicated using a separate indicator for each pattern, each indicator having a pointer which traverses a circular scale, one revolution corresponding to one cycle of phase change at the least common multiple frequency of the signals being compared and wherein each indicator has a mechanical counter driven through reduction gearing to indicate the number of complete revolutions of said pointer and wherein said adjustable divider is set for each comparison at the fundamental frequency so that the digital counter indicates iN decimal digits the correct lane count determined by the phase comparison at the fundamental frequency for setting the appropriate mechanical counter.
Claim 9
Dependent Claim
178 words
In a receiver for a phase comparison radio navigation system in which phase comparisons between signals normally radiated by spaced transmitters are effected at different multiples of a common fundamental frequency F to provide positional information with respect to fine patterns and in which phase comparisons at the fundamental frequency 1F are made for each pair of stations to provide coarser positional information, the improvement comprising a digital phase comparator to give a digital read-out count for effecting comparisons between signals at a frequency 1F, said digital phase comparator including a clock pulse source, a controllable divider dividing down the clock pulse frequency and a counter counting the divided down frequency pulses, the divider being controlled in accordance with the least common multiples of the normal transmissions from the two stations of each pair whereby the read-out count for each pair of stations is proportional to the time difference corresponding to the phase angle with proportionality factors for the different pairs of stations proportional to the multiples at which the normal signals of the corresponding pairs are compared.
Claim 10
Dependent Claim
178 words
In a receiver for a phase comparison radio navigation system in which phase comparisons between signals normally radiated by spaced transmitters are effected at different multiples of a common fundamental frequency F to provide positional information with respect to fine patterns and in which phase comparisons at the fundamental frequency 1F are made for each pair of stations to provide coarser positional information, the improvement comprising a digital phase comparator to give a digital read-out count for effecting comparisons between signals at a frequency 1F, said digital phase comparator including a clock pulse source, a controllable divider dividing down the clock pulse frequency and a counter counting the divided down frequency pulses, the divider being controlled in accordance with the least common multiples of the normal transmissions from the two stations of each pair whereby the read-out count for each pair of stations is proportional to the time difference corresponding to the phase angle with proportionality factors for the different pairs of stations proportional to the multiples at which the normal signals of the corresponding pairs are compared.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-12-05 | 1976-06-05 | 1976-12-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-05 | 1980-06-05 | 1980-12-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-05 | 1984-06-05 | 1984-12-05 | $7700.00 | Window Closed / Lapsed |