Patent US5835530A successfully refreshed from Google Patents.
US5835530A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bit characteristics measurement system for digitally modulated signals
Assignee: Authorize Net LLC
•
Filing: 1996-10-11
•
Granted: 1998-11-10
•
Expires: 2016-10-11
Abstract
Abstract System for measurement of the bit period (or bit rate or baud rate or symbol rate) and bit epoch (or symbol epoch) of a digitally modulated signal by extracting a bit time-of-transition array, determining an emphasis array with individual elements thereof relating to corresponding elements of the bit time-of-transition array, and using linear regression on the bit time-of-transition array with the emphasis. The emphasis array is formed from the signal amplitude, signal to interference ratio, or probability of a bit not being in error. One of several matched filters is dynamically selected based on the data content of the signal and used to detect bit transitions. The system has application in time varying multi-path fading environments. The system operates on signals with low SNR, high co-channel interference, or high intersymbol interference. Useful in transmitter identification, range finding, mobile transmitter location, and frequency hop intercept systems.
Inventors
- 👤 Kelly Davidson Hawkes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 08:27
CPC Classifications
H; H04; H04B; H04B17/00; H04B17/30; H04B17/382; H04B17/20; H04B17/27
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
84 words
An apparatus for measuring bit characteristics of a digitally modulated signal including a plurality of symbols comprising: time-of-transition means for extracting symbol time-of-transition elements from said digitally modulated signal to form a symbol time-of-transition array; emphasis means for determining emphasis elements from said digitally modulated signal to form an emphasis array with each said emphasis element corresponding to a corresponding time-of-transition element; and processing means for using linear regression on the said symbol time-of-transition array with said emphasis array to determine said bit characteristics.
Claim 2
Independent Claim
84 words
An apparatus for measuring bit characteristics of a digitally modulated signal including a plurality of symbols comprising: time-of-transition means for extracting symbol time-of-transition elements from said digitally modulated signal to form a symbol time-of-transition array; emphasis means for determining emphasis elements from said digitally modulated signal to form an emphasis array with each said emphasis element corresponding to a corresponding time-of-transition element; and processing means for using linear regression on the said symbol time-of-transition array with said emphasis array to determine said bit characteristics.
Claim 3
Dependent Claim
72 words
The apparatus of claim 1 wherein said digitally modulated signal has a signal level and said apparatus includes, an amplitude detector operating on said signal for generating a signal level waveform, and said emphasis means further operates to determine each emphasis element based on the signal level waveform such that each said time-of-transition element and each said corresponding emphasis element are both derived from at least a common portion of said signal.
Claim 4
Dependent Claim
64 words
The apparatus of claim 1 wherein said digitally modulated signal has a signal-to-interference ratio and said apparatus includes, means for measuring the signal-to-interference ratio, and said emphasis means further operates to determine each emphasis element based on the signal-to-interference ratio such that each said time-of-transition element and each said corresponding emphasis element are both derived from at least a common portion of said signal.
Claim 5
Dependent Claim
80 words
The apparatus of claim 1 wherein each of said symbols of said digitally modulated signal has one of plural possible symbol values and wherein said emphasis means includes, demodulation means operative for each particular symbol for selecting a particular symbol value that is most likely for said particular symbol, estimating means for estimating for each particular symbol a particular probability that the particular symbol value is not in error, means responsive to said particular probability for determining said emphasis element.
Claim 6
Dependent Claim
60 words
The apparatus of claim 1 wherein said digitally modulated signal has data content and said apparatus includes, demodulation means for recovering said data content of the digitally modulated signal, and said time-of-transition means includes reference filters for providing dynamically in time coefficients based on the data content of the received signal and includes a matched filter for receiving said coefficients.
Claim 7
Dependent Claim
19 words
The apparatus of claim 1 wherein said time-of-transition means includes receiving means for receiving a signal from a transmitter.
Claim 8
Dependent Claim
19 words
The apparatus of claim 6 wherein the receiving means includes an antenna, a down converter, and an A/D converter.
Claim 9
Dependent Claim
33 words
The apparatus of claim 6 wherein the receiving means includes an antenna, a radio receiver with FM and AM outputs, and means of performing A/D conversion of both said FM and AM outputs.
Claim 10
Dependent Claim
32 words
The apparatus of claim 1 wherein said digitally modulated signal is transmitted by a transmitter and said apparatus further includes a client system that identifies said transmitter based upon said bit characteristics.
Claim 11
Independent Claim
85 words
An apparatus for measuring a symbol period of a digitally modulated signal including a plurality of symbols comprising: time-of-transition means for extracting symbol time-of-transition elements from said digitally modulated signal to form a symbol time-of-transition array; emphasis means for determining emphasis elements from said digitally modulated signal to form an emphasis array with emphasis elements corresponding the time-of-transition elements of the transition array; and processing means for using linear regression on the said symbol time-of-transition array with said emphasis array to determine said symbol period.
Claim 12
Independent Claim
85 words
An apparatus for measuring a symbol period of a digitally modulated signal including a plurality of symbols comprising: time-of-transition means for extracting symbol time-of-transition elements from said digitally modulated signal to form a symbol time-of-transition array; emphasis means for determining emphasis elements from said digitally modulated signal to form an emphasis array with emphasis elements corresponding the time-of-transition elements of the transition array; and processing means for using linear regression on the said symbol time-of-transition array with said emphasis array to determine said symbol period.
Claim 13
Independent Claim
86 words
An apparatus for measuring a symbol epoch of a digitally modulated signal including a plurality of symbols comprising: time-of-transition means for extracting symbol time-of-transition elements from said digitally modulated signal to form a symbol time-of-transition array; emphasis means for determining emphasis elements from said digitally modulated signal to form an emphasis array with emphasis elements corresponding to the time-of-transition elements of the transition array; and processing means for using linear regression on the said symbol time-of-transition array with said emphasis array to determine said symbol epoch.
Claim 14
Independent Claim
86 words
An apparatus for measuring a symbol epoch of a digitally modulated signal including a plurality of symbols comprising: time-of-transition means for extracting symbol time-of-transition elements from said digitally modulated signal to form a symbol time-of-transition array; emphasis means for determining emphasis elements from said digitally modulated signal to form an emphasis array with emphasis elements corresponding to the time-of-transition elements of the transition array; and processing means for using linear regression on the said symbol time-of-transition array with said emphasis array to determine said symbol epoch.
Claim 15
Dependent Claim
139 words
A transmitter location system comprising: one or more transmitters, each transmitter transmitting a signal modulated with symbols of information, measuring means at each of two or more receive sites located at two or more receive site locations, respectively, each measuring means at a receive site determining a symbol epoch as a time when a specific one of said symbols arrives at said receive site, database means for storing information including a symbol epoch from each of said two or more receive sites, and location means for determining for each particular one of said one or more transmitters a particular location for said particular one of said one or more transmitters based on the difference in the symbol epochs retrieved from the database for said particular one of said one or more transmitters and said locations of the receive sites.
Claim 16
Dependent Claim
139 words
A transmitter location system comprising: one or more transmitters, each transmitter transmitting a signal modulated with symbols of information, measuring means at each of two or more receive sites located at two or more receive site locations, respectively, each measuring means at a receive site determining a symbol epoch as a time when a specific one of said symbols arrives at said receive site, database means for storing information including a symbol epoch from each of said two or more receive sites, and location means for determining for each particular one of said one or more transmitters a particular location for said particular one of said one or more transmitters based on the difference in the symbol epochs retrieved from the database for said particular one of said one or more transmitters and said locations of the receive sites.
Claim 17
Dependent Claim
32 words
The apparatus of claim 12 further comprising: distribution means for communicating the particular location for each particular one of said one or more transmitters to users at one or more remote locations.
Claim 18
Dependent Claim
36 words
The apparatus of claim 12 wherein said one or more transmitters are mobile cellular telephones, said signal modulated with symbols of information is a reverse control channel transmission, and each said receive site is ground based.
Claim 19
Dependent Claim
76 words
The apparatus of claim 12 wherein said measuring means at a receive site further includes: receiving means for receiving said signal and producing therefrom a pre-detection intermediate frequency signal, processing means operating on the pre-detection intermediate frequency signal for finding symbol times of transitions when modulation of the pre-detection intermediate frequency signal changes due to a symbol transition between adjacent symbols, linear regression means operating on the symbol times of transitions for determining said symbol epoch.
Claim 20
Dependent Claim
41 words
The apparatus of claim 15 wherein the linear regression means further includes: means for finding an emphasis factor for each symbol time of transition based on the quality of the pre-detection intermediate frequency signal in the vicinity of the symbol transition.
Claim 21
Dependent Claim
23 words
The apparatus of claim 12 wherein the measurement means includes a time standard derived from one or more global positioning system (GPS) receivers.
Claim 22
Dependent Claim
36 words
The apparatus of claim 12 wherein the location means further includes: error reduction means for reducing systematic errors by taking into account the symbol epochs of signals from one or more known transmitters at known locations.
Claim 23
Dependent Claim
26 words
The apparatus of claim 12 wherein said measuring means further includes: demodulation means to recover the symbols and decoding means to extract bits from the symbols.
Claim 24
Dependent Claim
19 words
The apparatus of claim 19 wherein the database also includes means to store one or more of said bits.
Claim 25
Independent Claim
221 words
An apparatus for measuring bit characteristics of a digitally modulated signal where the digitally modulated signal has a signal level, and data content and includes a plurality of symbols where each of said symbols has one of plural possible symbol values, said apparatus comprising: demodulation means for recovering said data content of the digitally modulated signal, time-of-transition means for extracting symbol time-of-transition elements from said digitally modulated signal to form a symbol time-of-transition array, said time-of-transition means including reference filters for providing dynamically in time coefficients based on said data content of the received signal and including a matched filter receiving said coefficients and responsively extracting said symbol time-of-transition elements based on said coefficients, an amplitude detector operating on said signal for generating a signal level waveform, emphasis means for determining emphasis elements from said digitally modulated signal to form an emphasis array with each said emphasis element corresponding to a corresponding time-of-transition element, said emphasis means operating to determine each emphasis element based on the signal level waveform such that each said time-of-transition element and each said corresponding emphasis element are both derived from at least a common portion of said signal, and processing means for using linear regression on the said symbol time-of-transition array with said emphasis array to determine symbol period and symbol epoch for said bit characteristics.
Claim 26
Independent Claim
221 words
An apparatus for measuring bit characteristics of a digitally modulated signal where the digitally modulated signal has a signal level, and data content and includes a plurality of symbols where each of said symbols has one of plural possible symbol values, said apparatus comprising: demodulation means for recovering said data content of the digitally modulated signal, time-of-transition means for extracting symbol time-of-transition elements from said digitally modulated signal to form a symbol time-of-transition array, said time-of-transition means including reference filters for providing dynamically in time coefficients based on said data content of the received signal and including a matched filter receiving said coefficients and responsively extracting said symbol time-of-transition elements based on said coefficients, an amplitude detector operating on said signal for generating a signal level waveform, emphasis means for determining emphasis elements from said digitally modulated signal to form an emphasis array with each said emphasis element corresponding to a corresponding time-of-transition element, said emphasis means operating to determine each emphasis element based on the signal level waveform such that each said time-of-transition element and each said corresponding emphasis element are both derived from at least a common portion of said signal, and processing means for using linear regression on the said symbol time-of-transition array with said emphasis array to determine symbol period and symbol epoch for said bit characteristics.
Claim 27
Independent Claim
133 words
An apparatus for measuring bit characteristics of a digitally modulated signal including a plurality of symbols comprising: demodulator means for extracting symbol time-of-transition elements, y i , from said digitally modulated signal to form a symbol time-of-transition array and for extracting symbol transition number elements, x i , from said digitally modulated signal to form a symbol number array; emphasis means for determining emphasis elements, e i , from said digitally modulated signal to form an emphasis array with each said emphasis element corresponding to a corresponding time-of-transition element; and processing means for using linear regression on the said symbol time-of-transition array with said emphasis array to determine said bit characteristics wherein said processing means finds the symbol period, m, and the symbol epoch, b, by minimizing Σ e.sub.i (y.sub.i -mx.sub.i -b)!.sup.2. 23.
Claim 28
Independent Claim
133 words
An apparatus for measuring bit characteristics of a digitally modulated signal including a plurality of symbols comprising: demodulator means for extracting symbol time-of-transition elements, y i , from said digitally modulated signal to form a symbol time-of-transition array and for extracting symbol transition number elements, x i , from said digitally modulated signal to form a symbol number array; emphasis means for determining emphasis elements, e i , from said digitally modulated signal to form an emphasis array with each said emphasis element corresponding to a corresponding time-of-transition element; and processing means for using linear regression on the said symbol time-of-transition array with said emphasis array to determine said bit characteristics wherein said processing means finds the symbol period, m, and the symbol epoch, b, by minimizing Σ e.sub.i (y.sub.i -mx.sub.i -b)!.sup.2. 23.
Claim 29
Dependent Claim
127 words
The apparatus of claim 22 wherein said processing means minimizes Σ e.sub.i (y.sub.i -mx.sub.i -b)!.sup.2 to avoid numerical round-off error propagation for a number of symbol transitions, N, by forming difference elements, d i , in a difference array and adjusted symbol transition number elements, f i , in an adjusted symbol transition number array as follows: d.sub.i =y.sub.i -m'x.sub.i -b' f.sub.i =x.sub.i -x.sub.N/2 where, m' and b' are the coarse estimates of the symbol period and symbol epoch and where x N/2 is the midpoint of the symbol transition number array, computing across the N elements of the arrays: ##EQU2## to determine refined estimates of the symbol period, m, and the symbol epoch, b, as follows: m=m'+(SS.sub.fd -S.sub.f S.sub.d)/(S.sub.ff S-S.sub.f.sup.2) b=b'+ S.sub.d +(S.sub.f +x.sub.N/2 S)(m'-m)!/S. 24.
Claim 30
Independent Claim
107 words
A method for measuring bit characteristics of a digitally modulated signal including a plurality of symbols comprising: extracting symbol time-of-transition elements, y i , from said digitally modulated signal to form a symbol time-of-transition array and extracting symbol transition number elements, x i , from said digitally modulated signal to form a symbol number array; determining emphasis elements, e i , from said digitally modulated signal to form an emphasis array with each said emphasis element corresponding to a corresponding time-of-transition element; and processing using linear regression on the said symbol time-of-transition array and said symbol number array with said emphasis array to determine said bit characteristics.
Claim 31
Independent Claim
107 words
A method for measuring bit characteristics of a digitally modulated signal including a plurality of symbols comprising: extracting symbol time-of-transition elements, y i , from said digitally modulated signal to form a symbol time-of-transition array and extracting symbol transition number elements, x i , from said digitally modulated signal to form a symbol number array; determining emphasis elements, e i , from said digitally modulated signal to form an emphasis array with each said emphasis element corresponding to a corresponding time-of-transition element; and processing using linear regression on the said symbol time-of-transition array and said symbol number array with said emphasis array to determine said bit characteristics.
Claim 32
Dependent Claim
25 words
The method of claim 24 wherein said processing means finds the period, m, and the epoch, b, by minimizing Σ e.sub.i (y.sub.i -mx.sub.i -b)!.sup.2. 26.
Claim 33
Dependent Claim
124 words
The of method claim 25 wherein said processing minimizes Σ e.sub.i (y.sub.i -mx.sub.i -b)!.sup.2 to avoid numerical round-off error propagation for a number of symbol transitions, N, by forming difference elements, d i , in a difference array and adjusted symbol transition number elements, f i , in an adjusted symbol transition number array as follows: d.sub.i =y.sub.i -m'x.sub.i -b'f.sub.i =x.sub.i -x.sub.N/2 where, m' and b' are the coarse estimates of the symbol period and symbol epoch and where x N/2 is the midpoint of the symbol transition number array, computing across the N elements of the arrays: ##EQU3## to determine refined estimates of the symbol period, m, and the symbol epoch, b, as follows: m=m'+(SS.sub.fd -S.sub.f S.sub.d)/(S.sub.ff S-S.sub.f.sup.2) b=b'+ S.sub.d +(S.sub.f +x.sub.N/2 S)(m'-m)!/S.
References Cited (Backward Citations)
US4559602A
Cited
US5005210A
Cited
US5369682A
Cited
US5329591A
Cited
US5327144A
Cited
US5448760A
Cited
US5724389A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-11-09 | 2002-05-11 | 2002-11-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-11-09 | 2006-05-11 | 2006-11-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-11-09 | 2010-05-11 | 2010-11-10 | $7700.00 | Window Closed / Lapsed |