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Patent US4587662A successfully refreshed from Google Patents.
US4587662A
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TDMA spread-spectrum receiver with coherent detection
Assignee: Alcatel Lucent NV
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Filing: 1984-01-25
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Granted: 1986-05-06
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Expires: 2004-01-25
Abstract
Abstract To utilize indirect-path signals in a receiver for fixed and mobile transmitter-receiver stations of a TDMA spread-spectrum digital radio system, coherent detection is employed. At the same time, the signal imaging the multipath profile is continuously regenerated by a regeneration circuit. The regeneration circuit provides a phase-coherent signal employed for demodulating the received signal.
Inventors
- 👤 Ulrich Langewellpott
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:50
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/66; H04B1/69
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
226 words
Receiver comprising a demodulator which is fed with an IF signal and contains a sync-tracking correlator connected to a sequence controller, and contains m character correlators connected to m character detectors and a decision stage, for fixed and mobile transmitter-receiver stations of a digital radio system employing time division multiple accessing and the spread-spectrum technique, wherein evey n bits to be transmitted are combined to form an n-bit group and encoded by a code character of an m-element alphabet, characterized in that each of the character detectors contains a mixer (11 1 -11 16 ) connected to a low-pass-filter (12 1-12 16 ), a sampling switch (13 1 -13 16 ), and a cyclically reset integrator (14 1 -14 16 ), and that each of the character correlators (7 1 -7 16 ) has its output connected to a delay line (10 1 -10 16 ) connected to a multiplexer (20) which has one of its inputs connected to the output of the sync-tracking correlator (6), is influenced by the output signal of a decision stage (15), and is connected to a regeneration circuit (21) which has its output connected to a detector (22) controlling the sampling switches (13 1 -13 16 ) and to the mixers (11 1 -11 16 ) and applies to the latter a signal having a waveform suitable for phase-coherent mixing.
Claim 2
Dependent Claim
226 words
Receiver comprising a demodulator which is fed with an IF signal and contains a sync-tracking correlator connected to a sequence controller, and contains m character correlators connected to m character detectors and a decision stage, for fixed and mobile transmitter-receiver stations of a digital radio system employing time division multiple accessing and the spread-spectrum technique, wherein evey n bits to be transmitted are combined to form an n-bit group and encoded by a code character of an m-element alphabet, characterized in that each of the character detectors contains a mixer (11 1 -11 16 ) connected to a low-pass-filter (12 1-12 16 ), a sampling switch (13 1 -13 16 ), and a cyclically reset integrator (14 1 -14 16 ), and that each of the character correlators (7 1 -7 16 ) has its output connected to a delay line (10 1 -10 16 ) connected to a multiplexer (20) which has one of its inputs connected to the output of the sync-tracking correlator (6), is influenced by the output signal of a decision stage (15), and is connected to a regeneration circuit (21) which has its output connected to a detector (22) controlling the sampling switches (13 1 -13 16 ) and to the mixers (11 1 -11 16 ) and applies to the latter a signal having a waveform suitable for phase-coherent mixing.
Claim 3
Dependent Claim
62 words
A receiver as claimed in claim 1, characterized in that the regeneration circuit (21) consists of a delay line (28) having its output connected through a first attenuator (29) to a summer (27) whose output is connected to the input of the delay line (28) and whose input is connected to the input of the regeneration circuit through a second attenuator (26).
Claim 4
Dependent Claim
26 words
A receiver as claimed in claim 2, characterized in that the delay provided by the delay line (28) is equal to the duration of one character.
Claim 5
Dependent Claim
35 words
A receiver as claimed in claim 2, characterized in that the second attenuator (16) provides an attentuation by a factor α smaller than one, and the first attenuator (29) an attenuation by the factor β=1-α.
Claim 6
Dependent Claim
17 words
A receiver as claimed in claim 4, characterized in that the factors of the attenuators are adjustable.
Claim 7
Dependent Claim
50 words
A receiver as claimed in claim 5, characterized in that the factor α of the second attenuator (26) is set at one at the beginning of each time slot for the duration of a synchronization preamble and a following sequence of a few known characters used as a training sequence.
Claim 8
Dependent Claim
73 words
A receiver as claimed in claim 1, characterized in that the output of the multiplexer (20) and the output of the regeneration circuit (21) are connected via a 90° phase shifter (24) and directly, respectively, to a phase comparator (23) having its output connected through a low-pass filter (25) to the control output of a voltage-controlled oscillator used as a local oscillator (4) which feeds a mixer (3) for producing the IF signal.
Claim 9
Dependent Claim
31 words
A receiver as claimed in claim 1, characterized that use is also made of biorthogonal m-element code characters, and that a sign reversal can then be effected in the multiplexer (20).
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) | 1989-05-05 | 1989-11-04 | 1990-05-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-05 | 1993-11-04 | 1994-05-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-05 | 1997-11-04 | 1998-05-06 | $7700.00 | Window Closed / Lapsed |