Patent JPS5927247A successfully refreshed from Google Patents.
US4752939A
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US
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Hidden preamble for frequency hopped synchronization
Assignee: Raytheon Co
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Filing: 1986-09-03
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Granted: 1988-06-21
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Expires: 2006-09-03
Abstract
Abstract A method is provided for achieving initial synchronization of the transmission and reception of a frequency hopped communication signal, which comprises the steps of transmitting a preamble defined by a sequence of synchronizing pulses on a single channel and transmitting random dummy pulses over the remaining channels to hide the preamble. The received signal is filtered to obtain the preamble which is then convolved with a stored replica of the preamble to produce a synchronizing signal that is used to synchronize frequency hopping of the receiver and transmitter in preparation for the transmission of information. The received, constituent pulses of the preamble are delayed and accumulated by a baseband correlator (18) to form a composite pulse whose magnitude is detected by a threshold detector (20). The threshold detector produces the synchronizing signal (22) when the accumulated pulse reaches a prescribed value indicating that all of the bits of the preamble have been received.
Inventors
- 👤 Frank Amoroso
- 👤 Norman L. Taylor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:29
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/69; H04B1/713; H04B1/7156
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
170 words
In a frequency hopped radio frequency communications system of the type in which the transmitted signal includes a plurality of information pulses which define at least a first message and are spread in a predefined pattern over a plurality of communication channels, a method of achieving initial synchronization of a transmitter with a receiver, comprising the steps of: (A) transmitting at least a first plurality of synchronization pulses defining at least a first preamble on a first single selected one of said communication channels, said first preamble marking the time of commencement of the transmission of said information pulses; (B) simultaneously with step (A), transmitting a plurality of dummy pulses respectively randomly distributed over said plurality of channels to hide said first preamble; (C) receiving said first preamble on said first selected channel at said receiver; (D) comparing the first preamble received in step (C) with a reference replica of said first preamble; and, (E) commencing transmission of said information pulses when the received first preamble matches the reference replica.
Claim 2
Dependent Claim
170 words
In a frequency hopped radio frequency communications system of the type in which the transmitted signal includes a plurality of information pulses which define at least a first message and are spread in a predefined pattern over a plurality of communication channels, a method of achieving initial synchronization of a transmitter with a receiver, comprising the steps of: (A) transmitting at least a first plurality of synchronization pulses defining at least a first preamble on a first single selected one of said communication channels, said first preamble marking the time of commencement of the transmission of said information pulses; (B) simultaneously with step (A), transmitting a plurality of dummy pulses respectively randomly distributed over said plurality of channels to hide said first preamble; (C) receiving said first preamble on said first selected channel at said receiver; (D) comparing the first preamble received in step (C) with a reference replica of said first preamble; and, (E) commencing transmission of said information pulses when the received first preamble matches the reference replica.
Claim 3
Dependent Claim
31 words
The method of claim 1, including the step of tuning said receiver to receive said single selected channel and to reject the pulses transmitted on the remaining ones of said channels.
Claim 4
Dependent Claim
16 words
The method of claim 1, wherein said preamble includes at least five of said synchronization pulses.
Claim 5
Dependent Claim
29 words
The method of claim 1, wherein step (C) is performed by filtering the signal received by said receiver to detect said selected channel and to reject the remaining channels.
Claim 6
Dependent Claim
32 words
The method of claim 1, wherein step (D) includes the step of delaying at least certain ones of said synchronization pulses and correlating each of said synchronization pulses with said reference replica.
Claim 7
Dependent Claim
119 words
The method of claim 1, including the steps of: (F) transmitting a second plurality of synchronization pulses defining a second preamble on a second single selected one of said communication channels which is different than said first channel; (G) simultaneously with step (F), transmitting a plurality of dummy pulses respectively randomly distributed over said plurality of channels to hide said second preamble; (H) receiving said second preamble on said second selected channel at said receiver; (I) comparing the second preamble received in step (H) with a reference replica of said second preamble; and (J) commencing transmission of information pulses defining a second message when the received second preamble matches the reference replica used in the comparison of step (I).
Claim 8
Independent Claim
133 words
A method of synchronizing the transmission and reception of a radio frequency communications signal which includes a plurality of data pulses transmitted over a plurality of frequencies in a predefined pattern, comprising the steps of: (A) transmitting a timing signal indicating the time of commencement of the transmission of said communications signal, said timing signal including a sequence of data pulses all transmitted on a single one of said frequencies and marking said time of commencement; (B) simultaneously with step (A), transmitting a plurality of data pulses respectively randomly distributed over the remaining frequencies to hide the sequence of data pulses which mark said time of commencement; (C) tuning said receiver to receive said one frequency; (D) detecting the sequence of data bits received in step (C) which mark said time of commencement.
Claim 9
Independent Claim
133 words
A method of synchronizing the transmission and reception of a radio frequency communications signal which includes a plurality of data pulses transmitted over a plurality of frequencies in a predefined pattern, comprising the steps of: (A) transmitting a timing signal indicating the time of commencement of the transmission of said communications signal, said timing signal including a sequence of data pulses all transmitted on a single one of said frequencies and marking said time of commencement; (B) simultaneously with step (A), transmitting a plurality of data pulses respectively randomly distributed over the remaining frequencies to hide the sequence of data pulses which mark said time of commencement; (C) tuning said receiver to receive said one frequency; (D) detecting the sequence of data bits received in step (C) which mark said time of commencement.
Claim 10
Dependent Claim
17 words
The method of claim 7, wherein said timing signal includes a sequence of at least five pulses.
Claim 11
Dependent Claim
23 words
The method of claim 7, wherein step (C) includes the step of filtering incoming signals to said receiver to separate said one frequency.
Claim 12
Dependent Claim
36 words
The method of claim 7, wherein step (D) includes the substep of delaying the pulses received in step (C) which mark said time of commencement and correlating the delayed pulses with a set of reference data.
Claim 13
Dependent Claim
27 words
The method of claim 7, wherein step (D) includes the substeps of convolving the pulses received in step (C) with a stored replica of said sequence pulses.
Claim 14
Dependent Claim
170 words
In a frequency hopped radio frequency communications system of the type in which the transmitted signal includes a plurality of information pulses which define at least a first message and are spread in a predefined pattern over a plurality of communication channels, a method of achieving initial synchronization of a transmitter with a receiver, comprising the steps of: (A) transmitting at least a first plurality of synchronization pulses defining at least a first preamble on a first single selected one of said communication channels, said first preamble marking the time of commencement of the transmission of said information pulses; (B) concurrently with step (A), transmitting a plurality of dummy pulses respectively frequency hopped over said plurality of channels to hide said first preamble; (C) receiving said first preamble on said first selected channel at said receiver; (D) comparing the first preamble received in step (C) with a reference replica of said first preamble; and, (E) commencing transmission of said information pulses when the received first preamble matches the reference replica.
Claim 15
Dependent Claim
170 words
In a frequency hopped radio frequency communications system of the type in which the transmitted signal includes a plurality of information pulses which define at least a first message and are spread in a predefined pattern over a plurality of communication channels, a method of achieving initial synchronization of a transmitter with a receiver, comprising the steps of: (A) transmitting at least a first plurality of synchronization pulses defining at least a first preamble on a first single selected one of said communication channels, said first preamble marking the time of commencement of the transmission of said information pulses; (B) concurrently with step (A), transmitting a plurality of dummy pulses respectively frequency hopped over said plurality of channels to hide said first preamble; (C) receiving said first preamble on said first selected channel at said receiver; (D) comparing the first preamble received in step (C) with a reference replica of said first preamble; and, (E) commencing transmission of said information pulses when the received first preamble matches the reference replica.
Claim 16
Dependent Claim
29 words
The frequency hopped radio communication system of claim 12 wherein said synchronization pulses are separated by at least one time interval wherein one of said dummy pulses is transmitted.
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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) | 1991-06-21 | 1991-12-21 | 1992-06-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-06-21 | 1995-12-21 | 1996-06-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-06-21 | 1999-12-21 | 2000-06-21 | $7700.00 | Window Closed / Lapsed |