Patent EP0143469A2 successfully refreshed from Google Patents.
EP0143469A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Receiver unit in radio communication system
Assignee: Fujitsu Ltd
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Filing: 1984-11-30
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Granted: —
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Expires: 2004-11-30
Abstract
Abstract A receiver unit for a radio communication system in which a transmitter unit outputs transmission data, modulated in accordance with a multilevel QAM method and containing a leakage carrier by addition of a DC offset signal to either one of the quadrature components forming the transmission data, to the receiver unit (200) through a transmission line, including: means for receiving the transmission data; means (21) for branching a signal received at the transmission data receiving means into first and second signal components forming the multilevel QAM data, each including the leakage carrier having a phase difference of 2 radian; first channel means (22, 24, 26, 28) for demodulating the first branched signal component and including a first synchronous detection circuit (22) and a first discriminator (28); second channel means (23, 25, 27, 29) for demodulating the second branched signal component and including a second synchronous detection circuit (23) and a second discriminator (29); and means for recovering the carrier including a control circuit (31, 32) for cancelling a noise component contained in the output signal from either one of the first and second synchronous detection circuits (22, 23) and for providing only a DC component representing a phase difference between a leakage carrier and a reference carrier, and a phase-locked loop (PLL) circuit (33, 34) for controlling the phase difference to zero and for providing phase-locked leakage carriers to the reference carriers, having a phase difference of radian, to the first and second synchronous detection circuits (22, 23).
Inventors
- 👤 Yukio Takeda
- 👤 Hiroshi Nakamura
- 👤 Eisuke Nakayama Bldg. 202 Fukuda
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 15:09
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/02; H04L27/06; H04L27/32; H04L27/34; H04L27/38; H04L27/3818
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
246 words
A receiver unit for a radio communication system in which a transmitter unit (100) outputs transmission data, modulated in accordance with a multilevel quadrature amplitude modulation (QAM) method and containing a leakage carrier (CR L ) by addition of a direct current (DC) offset signal to either one of quadrature components forming the transmission data, to the receiver unit (200) through a transmission line (150), characterised by: means for receiving transmission data; means (21) for branching a signal received at said transmission data receiving means into first and second signal components forming the multilevel QAM data, each including the leakage carrier having a phase difference of radian; first channel means (22,24,26,28) for demodulating the first branched signal component and including a first synchronous detection circuit (22) and a first discriminator (28); second channel means (23,25,27,29) for demodulating the second branched signal component and including a second synchronous detection circuit (23) and a second discriminator (29); and means (210) for recovering the carrier, including a control circuit (31,32), for cancelling a noise component contained in the output signal from either one of the first and second synchronous detection circuits and for providing only a DC component representing a phase difference between a leakage carrier and a reference carrier, and a phase-locked loop (PLL) circuit (33,34),- for controlling the phase difference to zero and for providing phase-locked leakage carriers to the reference carriers, having a phase difference of ― radian, to the first and second synchronous detection circuits.
Claim 2
Dependent Claim
246 words
A receiver unit for a radio communication system in which a transmitter unit (100) outputs transmission data, modulated in accordance with a multilevel quadrature amplitude modulation (QAM) method and containing a leakage carrier (CR L ) by addition of a direct current (DC) offset signal to either one of quadrature components forming the transmission data, to the receiver unit (200) through a transmission line (150), characterised by: means for receiving transmission data; means (21) for branching a signal received at said transmission data receiving means into first and second signal components forming the multilevel QAM data, each including the leakage carrier having a phase difference of radian; first channel means (22,24,26,28) for demodulating the first branched signal component and including a first synchronous detection circuit (22) and a first discriminator (28); second channel means (23,25,27,29) for demodulating the second branched signal component and including a second synchronous detection circuit (23) and a second discriminator (29); and means (210) for recovering the carrier, including a control circuit (31,32), for cancelling a noise component contained in the output signal from either one of the first and second synchronous detection circuits and for providing only a DC component representing a phase difference between a leakage carrier and a reference carrier, and a phase-locked loop (PLL) circuit (33,34),- for controlling the phase difference to zero and for providing phase-locked leakage carriers to the reference carriers, having a phase difference of ― radian, to the first and second synchronous detection circuits.
Claim 3
Dependent Claim
93 words
A receiver unit according to claim 1 characterised in that the control circuit (210) includes a digital-to-analog (D/A) converter (40), operatively connected to an output of either one of the first and second discriminators (28,29); an adder (41), operatively connected to an output of either one of the first and second synchronous detection circuits (22,23) at one input terminal and an output from the D/A converter (40) at another input terminal, for subtracting from the signal applied at one input terminal the signal applied at other input terminal; and a low-pass filter (32).
Claim 4
Dependent Claim
32 words
A receiver unit according to claim 2 characterised in that the PLL circuit includes a voltage-controlled oscillator (33) which receives a signal output from the control circuit at a control terminal thereof.
Claim 5
Dependent Claim
73 words
A receiver unit according to claim 3 characterised in that the P LL circuit further includes a radian phase shifter (34) connected to an output of the voltage-controlled oscillator (33) at an input terminal and either one of the synchronous detection circuits (22,23) at an output terminal for applying a phase-locked carrier having a phase shifted by 2 radian against a phase-locked carrier from the voltage-controlled oscillator (33), to said synchronous detection circuit.
Claim 6
Dependent Claim
260 words
A receiver unit for a radio communication system in which a transmitter unit (100) outputs transmission data, modulated in accordance with a multilevel quadrature amplitude modulation (QAM) method and containing a leakage carrier (CR L ) by addition of a direct current (DC) offset signal to either one of quadrature components forming the transmission data, to the receiver unit (200) through a transmission line (150), characterised by: means for receiving the transmission data; means (21) for branching a signal received at said transmission data receiving means into first and second signal components forming the multilevel QAM data, each including the leakage carrier having a phase difference of 2 radian; first channel means (22,24,26,28) for demodulating the first branched signal component and including a first synchronous detection circuit (22) and a first discriminator (28); second channel means (23,25,27,29) for demodulating the second branched signal component and including a second synchronous detection circuit (23) and a second discriminator (29); and means (210) for recovering the carrier, including a control circuit (31,32), for extracting a signal responsive to a phase difference between inputs and outputs of the first and second discriminators (28,29) for summing the extracted signal and an output signal at either one of the first and second synchronous detection circuits (22,23), and for providing only a DC component including the phase difference component, and a PLL circuit (33,34) for controlling the phase difference to zero and for providing phase-locked leakage carriers to the reference carriers, having a phase difference of 2 radian, to the first and second synchronous detection circuits (22,23).
Claim 7
Dependent Claim
260 words
A receiver unit for a radio communication system in which a transmitter unit (100) outputs transmission data, modulated in accordance with a multilevel quadrature amplitude modulation (QAM) method and containing a leakage carrier (CR L ) by addition of a direct current (DC) offset signal to either one of quadrature components forming the transmission data, to the receiver unit (200) through a transmission line (150), characterised by: means for receiving the transmission data; means (21) for branching a signal received at said transmission data receiving means into first and second signal components forming the multilevel QAM data, each including the leakage carrier having a phase difference of 2 radian; first channel means (22,24,26,28) for demodulating the first branched signal component and including a first synchronous detection circuit (22) and a first discriminator (28); second channel means (23,25,27,29) for demodulating the second branched signal component and including a second synchronous detection circuit (23) and a second discriminator (29); and means (210) for recovering the carrier, including a control circuit (31,32), for extracting a signal responsive to a phase difference between inputs and outputs of the first and second discriminators (28,29) for summing the extracted signal and an output signal at either one of the first and second synchronous detection circuits (22,23), and for providing only a DC component including the phase difference component, and a PLL circuit (33,34) for controlling the phase difference to zero and for providing phase-locked leakage carriers to the reference carriers, having a phase difference of 2 radian, to the first and second synchronous detection circuits (22,23).
Claim 8
Dependent Claim
140 words
A receiver unit according to claim 5 characterised in that the control circuit (31,32) in the carrier recovery circuit means includes a first multiplier (35) operatively connected to a first input of the second discriminator (29) at a first input terminal thereof and an output of the first discriminator (28) at a second input terminal thereof; a second multiplier (36) operatively connected to an input of the first discriminator (28) at a first input terminal and an output of the second discriminator (29) at a second input terminal; a divider (37) operatively connected to outputs of said first and second multipliers (35,36); an adder (39) operatively connected to an output of said divider (37) at one input terminal and an output of either one (23) of the first and second synchronous phase detection circuits (22,23); and a low-pass filter (32).
Claim 9
Dependent Claim
32 words
A receiver unit according to claim 6 characterised in that the PLL circuit includes a voltage-controlled oscillator (33) which receives a signal output from the control circuit at a control terminal thereof.
Claim 10
Dependent Claim
72 words
A receiver unit according to claim 7 characterised in that the PLL circuit further includes y radian phase shifter (34) connected to an output of the voltage-controlled oscillator (33) at an input terminal and either one of the synchronous detection circuits (22,23) at an output terminal for applying a phase-locked carrier having a phase shifted by radian against a phase-locked carrier from the voltage-controlled oscillator (33) to said synchronous detection circuit (22,23).
Claim 11
Dependent Claim
223 words
A receiver unit for a radio communication system in which a transmitter unit (100) outputs transmission data, modulated in accordance with a multilevel quadrature amplitude modulation (QAM) method and containing a leakage carrier (CR L ) by addition of a direct current (DC) offset signal to either one of quadrature components forming the transmission data, to the receiver unit (200) through a transmission line (150), characterised by: means for receiving transmission data; means (21) for branching a signal received at said transmission data receiving means into first and second signal components forming the multilevel QAM data, each including the leakage carrier (CR L ) having a phase difference of radian; first channel means (22,24,26,28) for demodulating the first branched signal component and including a first synchronous detection circuit (22) and a first discriminator (28); second channel means (23,25,27,29) for demodulating the second branched signal component and including a second synchronous detection circuit (23) and a second discriminator (29); and means (210) for recovering the carrier, including a control circuit (31,32) for extracting only the leakage carrier component due to the DC offset, and a PLL circuit for achieving synchronization of the leakage carrier with a reference carrier and for providing phase-locked leakage carriers to the reference carriers, having a phase difference of 2 radian, to the first and second synchronous detection circuits (22,23).
Claim 12
Dependent Claim
223 words
A receiver unit for a radio communication system in which a transmitter unit (100) outputs transmission data, modulated in accordance with a multilevel quadrature amplitude modulation (QAM) method and containing a leakage carrier (CR L ) by addition of a direct current (DC) offset signal to either one of quadrature components forming the transmission data, to the receiver unit (200) through a transmission line (150), characterised by: means for receiving transmission data; means (21) for branching a signal received at said transmission data receiving means into first and second signal components forming the multilevel QAM data, each including the leakage carrier (CR L ) having a phase difference of radian; first channel means (22,24,26,28) for demodulating the first branched signal component and including a first synchronous detection circuit (22) and a first discriminator (28); second channel means (23,25,27,29) for demodulating the second branched signal component and including a second synchronous detection circuit (23) and a second discriminator (29); and means (210) for recovering the carrier, including a control circuit (31,32) for extracting only the leakage carrier component due to the DC offset, and a PLL circuit for achieving synchronization of the leakage carrier with a reference carrier and for providing phase-locked leakage carriers to the reference carriers, having a phase difference of 2 radian, to the first and second synchronous detection circuits (22,23).
Claim 13
Dependent Claim
43 words
A receiver unit according to claim 9 characterised in that the control circuit in the carrier recovery circuit means includes a low-pass filter (32) operatively connected to an output of either one of the first and second synchronous detection circuits (22,23). (Figure 4)
Claim 14
Dependent Claim
33 words
A receiver unit according to claim 10 characterised in that the PLL circuit includes a voltage-controlled oscillator (33) which receives a signal output from the control circuit (32) at a control terminal thereof.
Claim 15
Dependent Claim
72 words
A receiver unit according to claim 11 characterised in that the PLL circuit further includes a radian phase shift-2 er (34) connected to an output of the voltage-controlled oscillator (33) at an input terminal and either one of the synchronous detection circuits (22,23) at an output terminal for applying a phase-locked carrier having a phase shifted by radian against a phase-locked carrier from the voltage-controlled oscillator, to said synchronous detection circuit (22,23).
Claim 16
Dependent Claim
54 words
A receiver unit according to claim 9 characterised in that the control circuit in the carrier recovery circuit means includes a hybrid circuit (46) for extracting either one of the first and second signal components, a circuit (47) mixing said extracted signal for extracting the leakage carrier, and a low-pass filter (48). (Figure 1)
Claim 17
Dependent Claim
32 words
A receiver unit according to claim 13 characterised in that the PLL circuit includes a voltage-controlled oscillator (49) which receives a signal output from the control circuit at a control terminal thereof.
Claim 18
Dependent Claim
72 words
A receiver unit according to claim 14 characterised in that the. PLL circuit further includes a i radian phase shifter (50) connected to an output of the voltage-controlled oscillator (49) at an input terminal and either one of the synchronous detection circuits (22,23) at an output terminal for applying .a phase-locked carrier having a phase shifted by radian against a phase-locked carrier from the voltage-controlled oscillator, to said synchronous detection circuit (22,23).
Claim 19
Dependent Claim
217 words
A receiver unit for a radio communication system in which a transmitter unit (100) outputs transmission data, modulated in accordance with a multilevel quadrature amplitude modulation (QAM) method and containing a leakage carrier (CR L ) by addition of a direct current (DC) offset signal to either one of quadrature components forming the transmission data, to the receiver unit (200) through a transmission line, characterised by: means for receiving transmission data; means (21) for branching a signal received at said transmission data receiving means into first and second signal components forming the multilevel QAM data, each including the leakage carrier having a phase difference of radian; first channel means (22,24,26,28) for demodulating the first branched signal component and including a first synchronous detection circuit (22) and a first discriminator (28); second channel means (23,25,27,29) for demodulating the second branched signal component and including a second synchronous detection circuit (23) and a second discriminator (29); and means (210,31,32,33,32) for recovering the carrier recovery, providing leakage carriers having a phase difference of 2 radian, phase-locked to corresponding reference carriers at the first and second synchronous detection circuits (22,23), cleared of a noise component and adjusted to zero phase difference between inputs and output of the first and second discriminator (28,29), to the first and second synchronous detection circuits (22,23).
Claim 20
Dependent Claim
217 words
A receiver unit for a radio communication system in which a transmitter unit (100) outputs transmission data, modulated in accordance with a multilevel quadrature amplitude modulation (QAM) method and containing a leakage carrier (CR L ) by addition of a direct current (DC) offset signal to either one of quadrature components forming the transmission data, to the receiver unit (200) through a transmission line, characterised by: means for receiving transmission data; means (21) for branching a signal received at said transmission data receiving means into first and second signal components forming the multilevel QAM data, each including the leakage carrier having a phase difference of radian; first channel means (22,24,26,28) for demodulating the first branched signal component and including a first synchronous detection circuit (22) and a first discriminator (28); second channel means (23,25,27,29) for demodulating the second branched signal component and including a second synchronous detection circuit (23) and a second discriminator (29); and means (210,31,32,33,32) for recovering the carrier recovery, providing leakage carriers having a phase difference of 2 radian, phase-locked to corresponding reference carriers at the first and second synchronous detection circuits (22,23), cleared of a noise component and adjusted to zero phase difference between inputs and output of the first and second discriminator (28,29), to the first and second synchronous detection circuits (22,23).
Claim 21
Dependent Claim
67 words
A radio communication system comprising: a transmitter (100) for outputting data modulated in accordance with a multilevel quadrature amplitude modulation (QAM) method and containing a leakage carrier (CR L ) by addition of a direct current (DC) offset signal to either of the quadrature components forming the transmission data; and a transmission line (150), characterised by a receiver unit according to any one of the preceding claims.
References Cited (Backward Citations)
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