US4980767A
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US
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Technique for determining signal dispersion characteristics in communications systems
Assignee: Nokia Bell Labs
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Filing: 1990-03-14
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Granted: 1990-12-25
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Expires: 2010-03-14
Abstract
Abstract The present invention covers the notion of determining signal dispersion characteristics, such as amplitude, phase and delay, by transmitting training sequences. More specifically, each sequence comprises a plurality of predetermined symbols and is transmitted two or more times. Detection of each training sequence is provided by a correlator at the receiver. This detection creates a signal peak for each training sequence at the output of the correlator. Between the peaks, a "quiet zone" is created which permits signal dispersion in this zone to be characterizerd with respect to amplitude, phase and delay. Two different quiet zones are utilized to resolve ambiguities which arise in determining the aforesaid signal dispersion characteristics.
Inventors
- 👤 Tzy-Hong Chao
- 👤 Burton R. Saltzberg
- 👤 Jin-Der Wang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 03:50
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/01; H04L; H04L27/00; H04L27/18; H04L27/22; H04L27/233; H04L27/2331; H04L25/00; H04L25/02; H04L25/03; H04L25/03006; H04L25/03012; H04L25/03114; H04L25/03133; H04L27/32; H04L27/34; H04L27/38; H04N5/00; H04N5/14; H04N5/21; H04N5/211; H04N7/015
Claims Analysis
Total Claims: 46
Claim 1
Independent Claim
83 words
Transmitter apparatus for use in a communications system, said apparatus comprising means for generating a first training sequence at least two times in succession and for generating a second training sequence at least two times in succession, said first training sequence including a first number of predetermined symbols and said second training sequence including a second number of predetermined symbols, said first and second numbers being different, and means for transmitting each of said first and second training sequences in associated time intervals.
Claim 2
Dependent Claim
83 words
Transmitter apparatus for use in a communications system, said apparatus comprising means for generating a first training sequence at least two times in succession and for generating a second training sequence at least two times in succession, said first training sequence including a first number of predetermined symbols and said second training sequence including a second number of predetermined symbols, said first and second numbers being different, and means for transmitting each of said first and second training sequences in associated time intervals.
Claim 3
Dependent Claim
37 words
The transmitter apparatus of claim 1 wherein said first and second sequences generated by said generating means are modified pseudorandom sequences in which a constant value is added to each symbol in at least one pseudorandom sequence.
Claim 4
Dependent Claim
20 words
The transmitter apparatus of claim 1 wherein said first and second sequences generated by said generating means are polyphase sequences.
Claim 5
Dependent Claim
44 words
The transmitter apparatus of claim 1 wherein said generating means generates said first training sequence a first number of times in succession and generates said second training sequence a second number of times in succession, said first and second number of times being different.
Claim 6
Dependent Claim
22 words
The transmitter apparatus of claim 1 wherein said transmitting means also transmits information signals in time intervals surrounding said associated time intervals.
Claim 7
Dependent Claim
31 words
The transmitter apparatus of claim 1 wherein said generating means generates a substantially zero dc signal in a predetermined time period immediately preceding the successive generation of said first training sequence.
Claim 8
Dependent Claim
31 words
The transmitter apparatus of claim 1 wherein said generating means generates a substantially zero dc signal in a predetermined time period immediately succeeding the successive generation of said first training sequence.
Claim 9
Dependent Claim
31 words
The transmitter apparatus of claim 1 wherein said generating means generates a substantially zero dc signal in a predetermined time period immediately preceding the successive generation of said second training sequence.
Claim 10
Dependent Claim
31 words
The transmitter apparatus of claim 1 wherein said generating means generates a substantially zero dc signal in a predetermined time period immediately succeeding the successive generation of said second training sequence.
Claim 11
Dependent Claim
40 words
The transmitter apparatus of claim 1 wherein said generating means generates a predetermined portion of said first training sequence comprising less than said first number in a first time period immediately preceding the successive generation of said first training sequence.
Claim 12
Dependent Claim
39 words
The transmitter apparatus of claim 1 wherein said generating means generates a predetermined portion of said first training sequence comprising less than said first number in a time period immediately succeeding the successive generation of said first training sequence.
Claim 13
Dependent Claim
39 words
The transmitter of claim 1 wherein said generating means generates a predetermined portion of said second training sequence comprising less than said second number in a first time period immediately succeeding the successive generation of said second training sequence.
Claim 14
Dependent Claim
26 words
The transmitter apparatus of claim 1 wherein said transmitting means further includes means for spectrally shaping said first and said second training sequences prior to transmission.
Claim 15
Dependent Claim
42 words
The transmitter apparatus of claim 13 wherein the predetermined symbols in said first and second training sequences occur at a predetermined symbol rate and said spectral shaping means includes a tapped delay line clocked at a multiple of said predetermined symbol rate.
Claim 16
Dependent Claim
21 words
The transmitter apparatus of claim 1 wherein said first and second sequences generated by said generating means are pseudorandom sequences. sequences.
Claim 17
Dependent Claim
20 words
The transmitter apparatus of claim 15 wherein said predetermined symbols in said pseudorandom sequence have equal positive and negative values.
Claim 18
Dependent Claim
21 words
The transmitter apparatus of claim 15 wherein said predetermined symbols in said pseudorandom sequence have values which are zero and non-zero.
Claim 19
Dependent Claim
119 words
Receiver apparatus for use in a communication system wherein any received signal has propagated through a communications medium in which signal dispersion may be present, said receiver apparatus comprising means for correlating each of a plurality of received first training sequences with a predetermined set of coefficients and for correlating each of a plurality of received second training sequences with another predetermined set of coefficients, each received first sequence including a first number of predetermined symbols and each received second training sequence including a second number of predetermined symbols, said first number being different from said second number, and means responsive to the correlated first and second training sequences for determining at least one characteristic of said signal dispersion.
Claim 20
Dependent Claim
119 words
Receiver apparatus for use in a communication system wherein any received signal has propagated through a communications medium in which signal dispersion may be present, said receiver apparatus comprising means for correlating each of a plurality of received first training sequences with a predetermined set of coefficients and for correlating each of a plurality of received second training sequences with another predetermined set of coefficients, each received first sequence including a first number of predetermined symbols and each received second training sequence including a second number of predetermined symbols, said first number being different from said second number, and means responsive to the correlated first and second training sequences for determining at least one characteristic of said signal dispersion.
Claim 21
Dependent Claim
34 words
The receiver apparatus of claim 18 wherein each of said first and second training sequences is received two times and said correlating means correlates each of said first and second training sequences two times.
Claim 22
Dependent Claim
27 words
The receiver apparatus of claim 18 wherein each of said first and second received training sequences are pseudorandom sequences and said correlating means correlates these pseudorandom sequences.
Claim 23
Dependent Claim
20 words
The receiver apparatus of claim 18 wherein said determining means determines the amplitude and delay characteristics of said signal dispersion.
Claim 24
Dependent Claim
34 words
The receiver apparatus of claim 18 further including a source of at least one carrier signal and said determining means determines the phase characteristic of said signal dispersion and controls said carrier signal source.
Claim 25
Dependent Claim
20 words
The receiver apparatus of claim 18 further including an equalizer and said determining means adjusts the operation of said equalizer.
Claim 26
Dependent Claim
44 words
The receiver apparatus of claim 18 further including an automatic gain control circuit through which each of said plurality of received first and second training sequences are coupled and said determining means includes means for controlling the gain of said automatic gain control circuit.
Claim 27
Dependent Claim
46 words
The apparatus of claim 18 wherein the predetermined symbols in said first and said second training sequences occur at a predetermined symbol rate and said correlating means provides correlation using a clock signal which is n times said predetermined symbol rate, where n is an integer≧1.
Claim 28
Dependent Claim
19 words
The apparatus of claim 18 wherein said predetermined set and said another predetermined set of coefficients are binary numbers.
Claim 29
Dependent Claim
15 words
The apparatus of claim 26 wherein the binary numbers have equal positive and negative values.
Claim 30
Dependent Claim
16 words
The apparatus of claim 26 wherein the binary numbers have values which are zero and non-zero.
Claim 31
Independent Claim
135 words
A method of determining at least one characteristic of signal dispersion in a communications system, said method comprising the steps of generating a first training sequence at least two times in succession and generating a second training sequence at least two times in succession, said first training sequence including a first number of predetermined symbols and said second training sequence including a second number of predetermined symbols, said first and second numbers being different, transmitting each of said first and second training sequences in associated time intervals, correlating each received first training sequence with a predetermined set of coefficients and for correlating each received second training sequence with another set of predetermined set of coefficients, and determining at least one characteristic of said signal dispersion in response to the correlated first and second training sequences.
Claim 32
Independent Claim
135 words
A method of determining at least one characteristic of signal dispersion in a communications system, said method comprising the steps of generating a first training sequence at least two times in succession and generating a second training sequence at least two times in succession, said first training sequence including a first number of predetermined symbols and said second training sequence including a second number of predetermined symbols, said first and second numbers being different, transmitting each of said first and second training sequences in associated time intervals, correlating each received first training sequence with a predetermined set of coefficients and for correlating each received second training sequence with another set of predetermined set of coefficients, and determining at least one characteristic of said signal dispersion in response to the correlated first and second training sequences.
Claim 33
Dependent Claim
153 words
A communications system comprising a transmitter and a receiver which are separated by a communications medium in which signal dispersion may be present, said transmitter comprising means for generating a first training sequence at least two times in succession and for generating a second training sequence at least two times in succession, said first training sequence including a first number of predetermined symbols and said second training sequence including a second number of predetermined symbols, said first and second numbers being different, and means for transmitting each of said first and second training sequences in associated time intervals, and said receiver comprising means for correlating each received first training sequence with a predetermined set of coefficients and for correlating each received second training sequence with another set of predetermined set of coefficients, and means responsive to the correlated first and second training sequences for determining at least one characteristic of said signal dispersion.
Claim 34
Dependent Claim
153 words
A communications system comprising a transmitter and a receiver which are separated by a communications medium in which signal dispersion may be present, said transmitter comprising means for generating a first training sequence at least two times in succession and for generating a second training sequence at least two times in succession, said first training sequence including a first number of predetermined symbols and said second training sequence including a second number of predetermined symbols, said first and second numbers being different, and means for transmitting each of said first and second training sequences in associated time intervals, and said receiver comprising means for correlating each received first training sequence with a predetermined set of coefficients and for correlating each received second training sequence with another set of predetermined set of coefficients, and means responsive to the correlated first and second training sequences for determining at least one characteristic of said signal dispersion.
Claim 35
Dependent Claim
100 words
Apparatus for use in a television signal transmitter wherein the transmitted television signal incorporates a vertical blanking interval in a video frame, said apparatus comprising means for generating a first training sequence at least two times in succession and for generating a second training sequence at least two times in succession, said first training sequence including a first number of predetermined symbols and said second training sequence including a second number of predetermined symbols, said first and second numbers being different, and means for transmitting said successively generated first and second training sequences in at least one vertical blanking interval.
Claim 36
Dependent Claim
100 words
Apparatus for use in a television signal transmitter wherein the transmitted television signal incorporates a vertical blanking interval in a video frame, said apparatus comprising means for generating a first training sequence at least two times in succession and for generating a second training sequence at least two times in succession, said first training sequence including a first number of predetermined symbols and said second training sequence including a second number of predetermined symbols, said first and second numbers being different, and means for transmitting said successively generated first and second training sequences in at least one vertical blanking interval.
Claim 37
Dependent Claim
16 words
The transmitter apparatus of claim 31 wherein said transmitting means also transmits video and audio signals.
Claim 38
Dependent Claim
23 words
The transmitter apparatus of claim 31 wherein said transmitting means transmits said video and audio signals in a high definition television signal format.
Claim 39
Dependent Claim
26 words
The transmitter apparatus of claim 31 wherein said transmitting means further includes means for spectrally shaping said first and said second training sequences prior to transmission.
Claim 40
Dependent Claim
43 words
The transmitter apparatus of claim 34 wherein the predetermined symbols in said first and said second training sequences occur at a predetermined symbol rate and said spectral shaping means includes a tapped delay line clocked at a multiple of said predetermined symbol rate.
Claim 41
Dependent Claim
16 words
The transmitter apparatus of claim 34 wherein said spectral shaping means provides raised cosine spectral shaping.
Claim 42
Dependent Claim
146 words
Apparatus for use in a television receiver wherein the transmitted television signal incorporates a vertical blanking interval and wherein the transmitted television signal propagates through a communications medium in which signal dispersion may be present, said receiver apparatus comprising means for correlating each of a plurality of received first training sequences with a predetermined set of coefficients and for correlating each of a plurality of received second training sequences with another predetermined set of coefficients, each first training sequence including a first number of predetermined symbols and each second training sequence including a second number of predetermined symbols, said first number being different from said second number, and said first and second training sequences being received during at least one of said vertical blanking intervals, and means responsive to the correlated first and second training sequences for determining at least one characteristic of said signal dispersion.
Claim 43
Dependent Claim
146 words
Apparatus for use in a television receiver wherein the transmitted television signal incorporates a vertical blanking interval and wherein the transmitted television signal propagates through a communications medium in which signal dispersion may be present, said receiver apparatus comprising means for correlating each of a plurality of received first training sequences with a predetermined set of coefficients and for correlating each of a plurality of received second training sequences with another predetermined set of coefficients, each first training sequence including a first number of predetermined symbols and each second training sequence including a second number of predetermined symbols, said first number being different from said second number, and said first and second training sequences being received during at least one of said vertical blanking intervals, and means responsive to the correlated first and second training sequences for determining at least one characteristic of said signal dispersion.
Claim 44
Dependent Claim
21 words
The receiver apparatus of claim 37 wherein said determining means determines the amplitude, delay and phase characteristics of said signal dispersion.
Claim 45
Dependent Claim
16 words
The transmitter apparatus of claim 37 wherein said spectral shaping means provides raised cosine spectral shaping.
Claim 46
Dependent Claim
47 words
The apparatus of claim 37 wherein the predetermined symbols in said first and said second training sequences occur at a predetermined symbol rate and said correlating means provides correlation using a clock signal which is n times said predetermined symbol rate, where n is an integer ≧1.
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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) | 1993-12-24 | 1994-06-25 | 1994-12-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-12-24 | 1998-06-25 | 1998-12-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-12-24 | 2002-06-25 | 2002-12-25 | $7700.00 | Window Closed / Lapsed |