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Communication system
RE40174 Communication system
Patent Drawings:Drawing: RE40174-10    Drawing: RE40174-100    Drawing: RE40174-101    Drawing: RE40174-102    Drawing: RE40174-103    Drawing: RE40174-104    Drawing: RE40174-105    Drawing: RE40174-106    Drawing: RE40174-107    Drawing: RE40174-108    
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(178 images)

Inventor: Oshima, et al.
Date Issued: March 25, 2008
Application: 09/668,068
Filed: September 25, 2000
Inventors: Oshima; Mitsuaki (Kyoto, JP)
Sakashita; Seiji (Osaka, JP)
Assignee: Matsushita Electric Industrial Co., Ltd. (Osaka, JP)
Primary Examiner: Ha; Dac V.
Assistant Examiner:
Attorney Or Agent: Wenderoth, Lind & Ponack, L.L.P.
U.S. Class: 375/219; 375/270; 375/301; 375/321
Field Of Search: 375/261; 375/265; 375/270; 375/277; 375/285; 375/296; 375/301; 375/321; 375/324; 375/340; 348/554; 348/726; 348/608
International Class: H04L 5/16; H04B 1/38
U.S Patent Documents:
Foreign Patent Documents: 2095435; 1499725; 2627574; 1569334; 0031193; 0122805; 0282298; 0311188; 0329158; 0365431; 0392538; 0448492; 0485105; 0485108; 0490552; 0506400; 0 506 400; 0525641; 0531046; 0540231; 1528854; 1529838; 2 187 611; 53-108215; 53-137657; 57-39629; 58-107740; 58-161427; 58-161547; 61-70861; 62-133842; 62-502932; 63-28145; 63-180222; 63-180280; 63-253738; 64-5135; 64-68144; 64-74836; 2-94814; 2-141049; 2-154583; 2-166979; 2-195732; 2-218279; 2-260726; 3-13145; 3-48587; 3-69295; 04-196822; 4-322592; 5-75568; 5-167633; 5-218978; 7-79415; 7-99522; 2004-159207; 52118; 85/04541; 86/07223; 89/08366; 91/20137; 92/14343; 92/22162
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Abstract: At the transmitter side, carrier waves are modulated according to an input signal for producing relevant signal points in a signal space diagram. The input signal is divided into, two, first and second, data streams. The signal points are divided into signal point groups to which data of the first data stream are assigned. Also, data of the second data stream are assigned to the signal points of each signal point group. A difference in the transmission error rate between first and second data streams is developed by shifting the signal points to other positions in the space diagram expressed at least in the polar coordinate system. At the receiver side, the first and/or second data streams can be reconstructed from a received signal. In TV broadcast service, a TV signal is divided by a transmitter into low and high frequency band components which are designated as first and second data streams respectively. Upon receiving the TV signal, a receiver can reproduce only the low frequency band component or both the low and high frequency band components, depending on its capability. Furthermore, a communication system based on an OFDM system is utilized for data transmission of a plurality of subchannels, wherein the subchannels are differentiated by changing the length of a guard time slot or a carrier wave interval of a symbol transmission time slot, or changing the transmission electric power of the carrier.
Claim: What is claimed is:

.[.1. A signal transmission and reception apparatus for transmitting and receiving an n-level VSB signal, the apparatus comprising a transmitter and a receiver; saidtransmitter comprising: a compression means for compressing an input video signal to a digital video compression signal; an error correction encoding means for adding an error correction code to the digital video compression signal to produce an errorcorrection coded signal; a modulation means for modulating the error correction coded signal to an n-level VSB modulation signal, said modulation means comprising a means for allocating code points along a uniaxial modulation coordinate system, and afilter means having a plurality of coefficients which are a series of impulse responses defined by plotting timebase responses to the VSB modulation signal along the in-phase axis and its orthogonal axis for filtering a series of said code pointsallocated along the uniaxial modulation coordinate system; and a transmission means for transmitting the modulation signal, and said receiver comprising: a means for receiving a transmitted n-level VSB modulation signal; a demodulation means fordemodulating the received n-level VSB modulation signal into a digital reception signal; an error correction means for error correcting the digital reception signal to obtain an error-corrected digital signal; and an expanding means for expanding theerror-corrected digital signal to obtain a video output signal..].

.[.2. A transmission and reception apparatus according to claim 1, wherein the error correction means comprises a trellis decoder..].

.[.3. A transmission and reception apparatus according to claim 2, wherein the trellis decoder is associated with a plurality of memories which each holds a number of selectable correct codes..].

.[.4. A transmission and reception apparatus according to claim 1, wherein the digital reception signal is divided into a high priority signal and a low priority signal, and wherein said error correction means comprises a high code gain firsterror correction means and a low code gain second error correction means, said first error correction means correcting the high priority signal..].

.[.5. A transmission and reception apparatus according to claim 4, wherein the high priority signal carries the address data for all data..].

.[.6. A transmission and reception apparatus according to claim 4, wherein the first error correction means comprises a trellis decoder..].

.[.7. A signal transmission and reception apparatus according to claim 1, further comprising a band path filtering means for filtering the n-level VSB modulation signal before being transmitted..].

.[.8. A signal transmission and reception apparatus for transmitting an n-level VSB signal, comprising: a compression means for compressing an input video signal into a digital video compression signal; an error correction encoding means foradding an error correction code to the digital video compression signal to produce an error correction coded signal; a modulation means for modulating the error correction coded signal to an n-level VSB modulation signal, said modulation meanscomprising a means for allocating code points along a uniaxial modulation coordinate system, and a filter means having a plurality of coefficients which are a series of impulse responses defined by plotting timebase responses to the VSB modulation signalalong the in-phase axis and its orthogonal axis for filtering a series of said code points allocated along the uniaxial modulation coordinate system; and a transmission means for transmitting the modulation signal..].

.[.9. A signal transmission apparatus according to claim 8, further comprising a band path filtering means for filtering the n-level VSB modulation signal before being transmitted..].

.[.10. A signal receiving apparatus comprising: a tuner for receiving a transmission signal containing a digital modulation signal and an analog modulation signal and for selecting the digital modulation signal using a local oscillation signal; an interference detecting means for detecting interference caused by the analog modulation signal from the digital modulation signal selected by the tuner; a notch filter means responsive to the interference detected by the interference detecting meansfor removing a carrier of the analog modulation signal in a same frequency band as a frequency band of the digital modulation signal; an error ratio calculating means for calculating a bit error ratio of an output of the notch filter means; and anautomatic frequency correcting means for changing a frequency of the local oscillation signal of the tuner according to a level of the interference detected by the interference detecting means and the bit error ratio calculated by the error ratiocalculating means to compensate for a frequency offset of the carrier of the analog modulated signal..].

.[.11. A signal receiving apparatus according to claim 10, wherein the digital modulation signal is an n-level VSB modulation signal..].

.[.12. A signal receiving apparatus comprising: a tuner for receiving a transmission signal containing at least one of a VSB modulated signal and a QAM modulated signal and for selecting one of the VSB modulated signal and the QAM modulatedsignal to obtain a selected signal; an analog-to-digital converter for converting the selected signal into a series of digital codes; a transversal filter provided on an orthogonal axis for suppressing a transmission distortion of the series of digitalcodes with respect to both orthogonal axes to obtain a series of filtered digital codes allocated on the orthogonal axes; a carrier recovery means for phase-compensating a carrier of the filtered digital codes allocated on the orthogonal axis outputtedfrom the transversal filter; and a control means for producing a control signal to extract detected codes at equal time intervals from the VSB modulated signal; a clock reproducing means for phase synchronizing entire codes of the QAM modulated signalwhen the selected signal is the QAM modulated signal and for phase synchronizing codes of the VSB modulated signal intermittently at predetermined intervals when the selected signal is the VSB modulated signal; and a decoding means for decoding anoutput of the carrier recovery means..].

.Iadd.13. A signal transmission and receiving apparatus for transmitting and receiving a VSB modulated signal having information of a first data stream and a second data stream, the apparatus comprising a transmission apparatus and a receivingapparatus, said transmission apparatus comprising: a trellis encoder operable to trellis encode the second data stream to produce a trellis encoded data stream; a modulator operable to modulate the first data stream, without being trellis encoded, to anm-level VSB modulated signal and modulate the trellis encoded data stream to an n-level VSB modulated signal, n being an integer larger than m, wherein the first data stream has synchronization data represented by at least one unique word; and atransmitter operable to transmit the m-level VSB modulated signal and the n-level VSB modulated signal; said receiving apparatus comprising: a demodulator operable to demodulate the m-level VSB modulated signal to the first data stream, and demodulatethe n-level VSB modulated signal to a demodulated data stream, wherein the demodulated data stream is reproduced according to the synchronization data represented by the at least one unique word; and a trellis decoder operable to trellis decode thedemodulated data stream to the second data stream..Iaddend.

.Iadd.14. A signal transmission apparatus for transmitting a VSB modulated signal having information of a first data stream and a second data stream, the apparatus comprising: a trellis encoder operable to trellis encode the second data streamto produce a trellis encoded data stream; a modulator operable to modulate the first data stream, without being trellis encoded, to an m-level VSB modulated signal and modulate the trellis encoded data stream to an n-level VSB modulated signal, n beingan integer larger than m, wherein the first data stream has synchronization data represented by at least one unique word; and a transmitter operable to transmit the m-level VSB modulated signal and the n-level VSB modulated signal..Iaddend.

.Iadd.15. A signal receiving apparatus comprising: a receiver operable to receive a transmitted VSB modulated signal having information of a first data stream, which has not been trellis encoded, and a second data stream, which had been trellisencoded, wherein the transmitted VSB modulated signal includes an m-level VSB modulated signal and an n-level VSB modulated signal, n being an integer larger than m, and the first data stream has synchronization data represented by at least one uniqueword; a demodulator operable to demodulate the m-level VSB modulated signal to the first data stream including the synchronization data represented by the at least one unique word, and to demodulate the n-level VSB modulated signal to a demodulated datastream, wherein the demodulated data stream is reproduced according to the synchronization data represented by the at least one unique word; and a trellis decoder operable to trellis decode the demodulated data stream to the second data stream..Iaddend.

.Iadd.16. A signal transmission and receiving method for transmitting and receiving a VSB modulated signal having information of a first data stream and a second data stream, the method comprising a transmission method and a receiving method,said transmission method comprising: trellis encoding the second data stream to produce a trellis encoded data stream; modulating the first data stream, without being trellis encoded, to an m-level VSB modulated signal and modulating the trellis encodeddata stream to an n-level VSB modulated signal, n being an integer larger than m, wherein the first data stream has synchronization data represented by at least one unique word; and transmitting the m-level VSB modulated signal and the n-level VSBmodulated signal; said receiving method comprising: demodulating the m-level VSB modulated signal to the first data stream, and demodulating the n-level VSB modulated signal to a demodulated data stream; wherein the demodulated data stream isreproduced according to the synchronization data represented by the at least one unique word; and trellis decoding the demodulated data stream to the second data stream..Iaddend.

.Iadd.17. A signal transmission method for transmitting a VSB modulated signal having information of a first data stream and a second data stream, said method comprising: trellis encoding the second data stream to produce a trellis encoded datastream; modulating the first data stream, without being trellis encoded, to an m-level VSB modulated signal and modulating the trellis encoded data stream to an n-level VSB modulated signal, n being an integer larger than m, wherein the first datastream has synchronization data represented by at least one unique word; and transmitting the m-level VSB modulated signal and the n-level VSB modulated signal..Iaddend.

.Iadd.18. A signal receiving method comprising: receiving a transmitted VSB modulated signal having information of a first data stream, which has not been trellis encoded, and a second data stream, which has been trellis encoded, wherein thetransmitted VSB modulated signal includes an m-level VSB modulated signal and an n-level VSB modulated signal, n being an integer larger than m, and the first data stream has synchronization data represented by at least one unique word; demodulating them-level VSB modulated signal to the first data stream having synchronization data and not being trellis encoded, and demodulating the n-level VSB modulated signal to a demodulated data stream, wherein the demodulated data stream is reproduced accordingto the synchronization data represented by the at least one unique word; and trellis decoding the demodulated data stream to the second data stream..Iaddend.
Description:
 
 
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