US4058713A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Equalization by adaptive processing operating in the frequency domain
Assignee: CARDION Inc A DE CORP
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Filing: 1976-09-20
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Granted: 1977-11-15
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Expires: 1996-09-20
Abstract
Abstract Equalization apparatus for a communication system transmitting through a time or frequency spread medium. The message to be transmitted is partitioned and transmitted in burst or frame by frame form. Each frame comprises the message (unknown at the receiver) followed by a test signal known at the receiver. Time gaps are provided between the message and test signals to avoid overlapping of the received message and test signals due to time-spreading. The received mutilated signals are processed in the frequency domain to obtain a reconstituted version of the transmitted message in the frequency domain. This is re-transformed into the time domain so that the reconstituted message available at the receiver is a close replica of the message which was originally available only at the transmitter.
Inventors
- 👤 Michael J. DiToro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:15
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/005
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
109 words
A signal processor for processing a message signal received over a time-spread or frequency-spread medium to produce an estimate of the transmitted message signal in which a known signal is transmitted along with said message signal and received therewith, comprising: a. first means for converting all said received signals to the frequency domain; b. second means for providing a representation of said known signal; c. processing means responsive to said first and second means to produce an estimate of the transmitted message signal in the frequency domain; and, d. third means for converting the frequency domain form of the estimate of said transmitted message signal to the time domain.
Claim 2
Dependent Claim
109 words
A signal processor for processing a message signal received over a time-spread or frequency-spread medium to produce an estimate of the transmitted message signal in which a known signal is transmitted along with said message signal and received therewith, comprising: a. first means for converting all said received signals to the frequency domain; b. second means for providing a representation of said known signal; c. processing means responsive to said first and second means to produce an estimate of the transmitted message signal in the frequency domain; and, d. third means for converting the frequency domain form of the estimate of said transmitted message signal to the time domain.
Claim 3
Dependent Claim
36 words
The apparatus of claim 1 wherein said second means provides a time domain representation of said known test signal and said processing means includes means to produce a frequency domain form of said known test signal.
Claim 4
Dependent Claim
19 words
The apparatus of claim 1 wherein said second means provides a frequency domain representation of said known test signal.
Claim 5
Dependent Claim
61 words
The apparatus of claim 1 in which said first means responds to said received message signal m' i (t) and known test signal b' i (t) to produce corresponding frequency domain form M' i (f) and B' i (f) and said processing means provides B(f)M' i (f)/B' i (f) wherein B(f) is the frequency domain form of said known test signal.
Claim 6
Dependent Claim
30 words
The apparatus of claim 4 which includes means for determining channel noise powder and said processing means multiplies the quantity B(f)M' i (f)/B' i (f) by a noise related quantity.
Claim 7
Dependent Claim
21 words
The apparatus of claim 5 including means for providing kN o wherein 1/4>K>2 and N o is said channel noise power.
Claim 8
Dependent Claim
59 words
The apparatus of claim 6 which includes means for separately comparing received known and received message signal power in a plurality of frequency bands with said quantity kN o and for reducing, to zero, a received message signal in any frequency band if, for that band, kN o is greater than either received known or received message signal power.
Claim 9
Dependent Claim
147 words
The apparatus of claim 1 in which said first means produces a transform B' i (f) for said received known signal b'(t) and a transform M' i (f) for said received message signal m' i (t), each transform comprising a series of Fourier coefficients related to the contribution to the associated signal in a different frequency band, said processing means producing a further transform related to the transmitted message signal and comprising a series of Fourier coefficients, by computing M".sub.i (f) = M'.sub.i (f)B(f)/B'.sub.i (f) means for detecting channel noise power N o , and producing a signal kN o , means for comparing kN o with |B' i | 2 and |M' i | 2 in each said frequency band and for reducing the associated Fourier coefficient of M" to zero if kN o >|B' i | 2 or kN o >|M' i | 2 .
Claim 10
Dependent Claim
7 words
The apparatus of claim 8 wherein 1/4<k<2.
Claim 11
Dependent Claim
34 words
The apparatus of claim 8 in which said processing means further includes fourth means for multiplying the product B(f)M' i (f)/B' i (f) by G o wherein G o is a noise related parameter.
Claim 12
Dependent Claim
14 words
The apparatus of claim 10 wherein said fourth means includes means for computing ##EQU1##
Claim 13
Dependent Claim
150 words
A communications system for communicating message signals from a transmitting station to a geographically remote receiving station over a time-spread or frequency-spread medium including: transmitting apparatus, at said transmitting station, responsive to a message signal to transmit the same interleaved with a known signal. receiving apparatus at said geographically remote receiving station responsive to the received form of said message signal and said known signal, to provide an estimate of the transmitted form of said message signal, said receiving apparatus including: a. means for converting all said received signals to the frequency domain; b. second means for providing a representation of said known test signal; c. processing means responsive to said first and second means to produce an estimate of the transmitted message signal in the frequency domain; and, d. third means for converting the frequency domain form of the estimate of said transmitted message signal to the time domain.
Claim 14
Dependent Claim
150 words
A communications system for communicating message signals from a transmitting station to a geographically remote receiving station over a time-spread or frequency-spread medium including: transmitting apparatus, at said transmitting station, responsive to a message signal to transmit the same interleaved with a known signal. receiving apparatus at said geographically remote receiving station responsive to the received form of said message signal and said known signal, to provide an estimate of the transmitted form of said message signal, said receiving apparatus including: a. means for converting all said received signals to the frequency domain; b. second means for providing a representation of said known test signal; c. processing means responsive to said first and second means to produce an estimate of the transmitted message signal in the frequency domain; and, d. third means for converting the frequency domain form of the estimate of said transmitted message signal to the time domain.
Claim 15
Dependent Claim
36 words
The apparatus of claim 12 wherein said second means provides a time domain representation of said known test signal and said processing means includes means to produce a frequency domain form of said known test signal.
Claim 16
Dependent Claim
23 words
The apparatus of claim 12 wherein said second means provides a frequency domain representation of said known test signal to said processing means.
Claim 17
Dependent Claim
61 words
The apparatus of claim 12 in which said first means responds to said received message signal m' i (t) and known test signal b' i (t) to produce corresponding frequency domain form M' i (f) and B' i (f) and said processing means provides B(f)M' i (f)/B' i (f) wherein B(f) is the frequency domain form of said known test signal.
Claim 18
Dependent Claim
30 words
The apparatus of claim 15 which includes means for determining channel noise power and said processing means multiplies the quantity B(f)M' i (f)/B' i (f) by a noise related quantity.
Claim 19
Dependent Claim
21 words
The apparatus of claim 16 including means for providing kN o wherein 1/4<k<2 and N o is said channel noise power.
Claim 20
Dependent Claim
58 words
The apparatus of claim 17 which includes means for separately comparing received known and received message signal power in each said frequency band with said quantity kN o and for reducing, to zero, a received message signal in any frequency band if, for that band, kN o is greater than either received known or received message signal power.
Claim 21
Dependent Claim
154 words
The apparatus of claim 12 in which said first means produces a transform B' i (f) of said received known signal b' i (t) and a transform M' i (f) for said received message signal m' i (t), each transform comprising a series of Fourier coefficients related to the contribution to the associated signal in a different frequency band, said processing means producing a further transform related to the transmitted message signal and comprising a series of Fourier coefficients by computing M" i (f) = M' i (f)B(f)/B' i (f), means for detecting channel noise power N o , and producing a signal kN o . means for comparing kN o with |B' i | 2 and |M' i | 2 in each said frequency band and for reducing the associated Fourier coefficient of M" i to zero if kN o is greater than |B' i | 2 or |M' i | 2 .
Claim 22
Dependent Claim
8 words
The apparatus of claim 19 in which 1/4<k<2.
Claim 23
Dependent Claim
34 words
The apparatus of claim 19 in which said processing means further includes fourth means for multiplying the product B(f)M' i (f)/B' i (f) by G o wherein G o is a noise related parameter.
Claim 24
Dependent Claim
14 words
The apparatus of claim 21 wherein said fourth means includes means for computing ##EQU2##
Claim 25
Dependent Claim
26 words
The apparatus of claim 12 in which said transmitting means transmits a known signal having a substantially flat frequency spectrum throughout a frequency band of interest.
Claim 26
Dependent Claim
25 words
The apparatus of claim 12 in which said transmitter transmits in burst form and interleaves a known signal burst within each pair of message bursts.
Claim 27
Dependent Claim
16 words
The apparatus of claim 24 in which said known signal has a substantially flat frequency spectrum.
Claim 28
Dependent Claim
15 words
The apparatus of claim 25 in which said known signal comprises a pulse sequence 1111100110101.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-11-14 | 1981-05-16 | 1981-11-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-11-14 | 1985-05-16 | 1985-11-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-11-14 | 1989-05-16 | 1989-11-15 | $7700.00 | Window Closed / Lapsed |