Pulse or digital communications – Receivers – Angle modulation
Reexamination Certificate
2000-06-16
2004-01-27
Vo, Don N. (Department: 2631)
Pulse or digital communications
Receivers
Angle modulation
C375S332000, C375S284000, C375S371000, C329S304000
Reexamination Certificate
active
06683921
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an received-signal absolute phasing apparatus of receiver, particularly to a received-signal absolute phasing apparatus of receiver, which makes the following coincide with the transmission side: signal point arrangements of received I and Q base-band signals of two series obtained by receiving and demodulating: a signal to be PSK-modulated in which at least an 8PSK-modulated digital signal among 8PSK-modulated digital signal, QPSK-modulated digital signal, and BPSK-modulated digital signal are time-multiplexed with a BPSK-modulated frame synchronizing signal, by a hierarchical transmission system; or a signal to be PSK-modulated in which at least 8PSK-modulated digital signal and QPSK-modulated digital signal among 8PSK-modulated digital signal, QPSK-modulated digital signal, and BPSK-modulated digital signal are time-multiplexed with a BPSK-modulated frame synchronizing signal, by the system.
BACKGROUND ART
Practical use of digital satellite TV broadcasting is advanced which uses a plurality of modulation systems different from each other in required C/N such as a hierarchical transmission system for repeatedly transmitting a wave to be 8PSK-modulated, a wave to be QPSK-modulated, and a wave to be BPSK-modulated by time-multiplexing the waves.
FIG. 11A
is an illustration showing a frame configuration of a hierarchical transmission system. One frame is configured by a frame synchronizing signal pattern comprising 32 BPSK-modulated symbols (among 32 symbols, 20 latter-half symbols are actually used as a frame synchronizing signal), a TMCC (Transmission and Multiplexing Configuration Control) pattern for identifying a transmission multiplexing configuration comprising 128 BPSK-modulated symbols, a super-frame-identifying signal pattern comprising 32 symbols (among 32 symbols, 20 latter-half symbols are actually used as a super-frame-identifying signal), main signal of 203 8PSK(trellis-CODEC-8PSK)-modulated symbols, burst symbol signal (BS) of 4 symbols obtained by BPSK-modulating a pseudo random-noise (PN) signal, main signal of 203 8PSK(trellis-CODEC-8PSK)-modulated symbols, burst symbol signal (BS) of 4 symbols obtained by BPSK-modulating a pseudo random-noise (PN) signal, . . . , main signal of 203 QPSK-modulated symbols, burst symbol signal (BS) of 4 symbols obtained by BPSK-modulating a pseudo random-noise (PN) signal, main signal of 203 QPSK-modulated symbols, and burst symbol signal (BS) of 4 BPSK-modulated symbols in order.
In case of a receiver for receiving digital waves to be modulated (waves to be PSK-modulated) according to the hierarchical transmission system, an intermediate-frequency signal of a received signal received by a receiving circuit is demodulated by a demodulating circuit and I and Q base-band signals of two series showing instantaneous values of I axis and Q axis orthogonal to each other every symbol (hereafter, I and Q base-band signals are also referred to as I and Q symbol stream data values) are obtained. By acquiring a frame synchronizing signal from the demodulated I an Q base-band signals, obtaining a present received-signal-phase rotation angle from the signal point arrangement of the acquired frame synchronizing signal, and antiphase-rotating the demodulated I and Q base-band signals in accordance with the obtained received-signal-phase rotation angle, absolute phase generation for adjusting the I and Q base-band signals to a transmission-signal phase angle is performed by an absolute-angle-generating circuit.
As shown in
FIG. 12
, an absolute-phase generating circuit of a receiver for receiving waves to be PSK-modulated according to a conventional hierarchical transmission system is configured by a frame sync detecting/regenerating circuit
2
serving as frame sync acquiring means provided for the output side of a demodulating circuit
1
to acquire a frame synchronizing signal, a remapper
7
serving as antiphase rotating means comprising a ROM, and received-signal-phase rotation angle detecting circuit
8
serving as received-signal-phase rotation angle detecting means. Symbol
9
denotes a transmission-configuration identifying circuit for identifying a transmission multiplexing configuration shown in
FIG. 11A
, which outputs a 2-bit-modulating-system identifying signal DM.
The demodulating circuit
1
obtains I and Q base-band signals by quadrature-detecting an intermediate frequency signal IF. In the demodulating circuit
1
, symbol
10
denotes a carrier-wave regenerating circuit for regenerating two reference carrier waves f
c1
(=cos &ohgr;t) and f
c2
(=sin &ohgr;t) whose frequencies and phases synchronize with a received carrier wave and which is orthogonal to each other because their phase are shifted by 90° from each other,
60
and
61
denote multipliers for multiplying the intermediate frequency signal IF by f
c1
and f
c2
,
62
and
63
denote A/D converters for A/D-converting outputs of the multipliers
60
and
61
at a sampling rate two times larger than a symbol rate,
64
and
65
denote digital filters for performing band restriction to outputs of the A/D converters
62
and
63
through digital signal processing, and
66
and
67
denote thinning circuits for thinning outputs of the digital filters
64
and
65
at a ½ sampling rate and outputting I and Q base-band signals (I and Q symbol stream data values) of two series showing instantaneous values of I-axis and Q-axis every symbol. The thinning circuits
66
and
67
transmit I and Q base-band signals I(
8
) and Q(
8
) (a numeral in parentheses shows the number of quantization bits and is hereafter also simply referred to as I and Q by omitting the number of quantization bits) having 8 quantization bits (two's complement system).
Mapping for each modulation system at the transmission side will be described below by referring to
FIGS. 13A-13C
.
FIG.13A
shows signal point arrangements on an I-Q phase plane (also referred to as I-Q vector plane or I-Q signal space diagram) using 8PSK for a modulation system. The 8PSK modulation system makes it possible to transmit a 3-bit digital signal (abc) by one symbol. Combination of bits configuring one symbol includes eight ways such as (000), (001), (010), (011), (100), (101), (110), and (111). These 3-bit digital signals are converted into signal point arrangements “0” to “7” on the transmission-side I-Q phase plane in FIG.
13
A and this conversion is referred to as 8PSK mapping.
In case of the example shown in
FIG. 13A
, the bit string (000) is converted into a signal point arrangement “0”, the bit string (001) into a signal point arrangement “1”, the bit string (011) into a signal point arrangement “2”, the bit string (010) into a signal point arrangement “3”, the bit string (100) into a signal point arrangement “4”, the bit string (101) into a signal point arrangement “5”, the bit string (111) into a signal point arrangement “6”, and the bit string (110) into a signal point arrangement “7”.
FIG. 13B
shows signal point arrangements on an I-Q phase plane at the time of using QPSK for a modulation system. The QPSK modulation system makes it possible to transmit a 2-bit digital signal (de) by one symbol. Combination of bits configuring the symbol includes four ways such as (00), (01), (10), and (11). In case of the example in
FIG. 13B
, the bit string (00) is converted into a signal point arrangement “1”, the bit string (01) into a signal point arrangement “3”, the bit string (11) into a signal point arrangement “5”, and the bit string (10) into a signal point arrangement “7”.
FIG. 13C
shows signal point arrangements at the time of using BPSK for a modulation system. The BPSK modulation system transmits a 1-bit signal (f) by one symbol. In case of the digital signal (f), bit (
0
) is converted into a signal point arrangement “0” and bit (
1
) is converted into a signal point arrangement “4”. Relations between signal point arrangements and arrangement numbers of modulation systems are the same each other on the basis of 8BPSK.
I axis and Q a
Horii Akihiro
Shiraishi Kenichi
Ghulamali Qutbuddin
Kabushiki Kaisha Kenwood
Robinson Eric J.
Robinson Intellectual Property Law Office P.C.
Vo Don N.
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