JPS6013344B2 - Orthogonal multiplex signal transmission/reception method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an orthogonal multiplex signal transmission/reception system and a transmission/reception device, and in particular modulates a plurality of baseband PAM signals (pulse width modulation signals) with carriers having different frequencies or phases, and The present invention relates to an orthogonal multiplex signal transmitting/receiving system and a transmitting/receiving apparatus that transmits a highly efficient PAM signal at a speed substantially equal to the Nyquist speed by orthogonally multiplexing modulated signals of the above and transmitting the modulated signals.

The principle of the orthogonal multiplex transmission system for PAM signals was first introduced in 1966.
The publication “The BellS$t” published in the United States in February
No. 1775 of ``emTechnical Joumal''
Page - The paper “Synthesis” published on page 1796
of Matsu nd-Limi ni d ○nhogonaI S
ignals phantom v M mountain tichanneIData
Transmlsson" (Reference 1), but in order to realize this method, it is necessary to perform correlation detection especially on the receiving side, which leads to an increase in the size of the transmitter/receiver. Not adopted.

After this, in November 1967, Higyoumono 'The
Paper published in "Technical Journal" page 2163 - 217 Towariko "A snakener"
Aljzed Criterion a
and an Optimum Linear Rece
iver's r a P mountain se Mod mountain atjonSy
A test of the generalized Nyquist theorem is performed in s and m'' (Reference 2), and an orthogonal multiplex transmission system that does not require correlation detection on the receiving side is proposed.

Furthermore, in recent years, based on the principles of document The transmission method is an orthogonal VSB transmission method, and the transmitter/receiver for this is called an orthogonal VSB transmitter/receiver.

However, such a conventional orthogonal VSB transmitting/receiving apparatus requires a VSB shaping filter for each baseband PAM signal, which has the disadvantage of increasing the size of the apparatus. The purpose of the present invention is to convert each baseband PAM signal to VS
An orthogonal multiplexed signal transmission/reception method and a transmission/reception device that enable high-efficiency PAM transmission with a small equipment scale by orthogonally modulating every two channels instead of B modulation and orthogonally multiplexing these orthogonally modulated (Q small 4) signals. Our goal is to provide the following.

The orthogonal multiplex signal transmission/reception system of the present invention transmits 2N channel baseband pulse amplitude modulation signals synchronized with each other with a clock cycle T and a frequency difference of 1/2 between adjacent carriers.
Transmission/reception of orthogonal multiplexed signals that are converted into N orthogonal amplitude modulation signals by T cycles and whose phases are set so that each carrier maintains an in-phase or orthogonal relationship with each other, and then multiplexes and transmits these signals. In this method, only two in-phase channels and two orthogonal channels adjacent to each other in the frequency domain are given a delay difference of T/2 seconds between their corresponding transmitting side baseband pulse amplitude modulated signals. , is characterized in that inter-symbol interference and inter-channel interference are reduced to almost zero at the identification time of each baseband signal demodulated on the receiving side.

Another orthogonal multiplex signal transmission/reception system of the present invention uses two adjacent carrier frequencies whose phases are set so as to maintain an in-phase or orthogonal relationship with each other.
a quadrature amplitude modulated signal and a quadrature amplitude modulated signal or a quadrature amplitude modulated signal and a lower residual sideband signal or an upper residual sideband signal and a lower residual sideband signal or an upper residual sideband signal and When the orthogonal amplitude modulation signals correspond to each other, the difference between the two carrier frequencies and the end is 1/T cycle, and the upper residual side wave is generated for each of the two carrier frequencies n- and k. band signal and upper vestigial sideband signal or lower vestigial sideband signal and lower vestigial sideband signal or quadrature amplitude modulated signal and upper vestigial sideband signal or lower vestigial sideband signal and quadrature amplitude modulated signal correspond to each other, the difference between the two carrier frequencies and pk is 1 to 2T cycles, and the orthogonal amplitude modulation signal corresponds to the specific carrier frequency k, or the upper residual sideband signal When the lower vestigial sideband signals and lower vestigial sideband signals correspond simultaneously, two carriers, sm2t and cos2kt, are used; otherwise, one carrier, sm2ribkt or cos27pukt, is used. Then, using a total of (2N-M) carriers, baseband pulse amplitude modulated waves of (2N0M) channels synchronized with each other with a clock period of T seconds are combined with N orthogonal amplitude modulated signals and M residual side signals. In an orthogonal multiplex signal transmission/reception method that converts into waveband signals and then multiplexes and transmits them, it only supports two in-phase channels and two orthogonal channels that are adjacent to each other in the frequency domain. By giving a delay difference of T/2 seconds between baseband pulse amplitude modulated signals on the transmitting side, inter-symbol interference and inter-channel interference can be made almost zero at the separation time of each baseband signal demodulated on the receiving side. It is characterized by

Next, the present invention will be explained in detail with reference to the drawings.

Generally, a frequency multiplex transmission system for PAM signals can be expressed as shown in FIG. In FIG. 1, reference numerals 1, . Also, reference number 3
, ~3n are n modulators, reference numbers 4 and ~4n are modulation carrier generators that supply modulation carriers to these n modulators, and reference numbers 5 and ~5n are modulated signals. n filters that perform spectral shaping. Furthermore, reference numerals 6 and 6n are frequency multiplexing devices that perform frequency multiplexing by adding n spectrally shaped modulated signals obtained by Obijo passing filters 5 and 5n, and reference numeral 7 is a transmission line, and reference numerals 13,
~13n are n band separation filters, reference numeral 8
, ~8n are n demodulators, and reference numerals 9, ~9n are n demodulation carrier generators that supply demodulation carriers to the demodulators 8, ~8n. Also, reference numbers IQ, ~1
0n is n receiving filters, reference numbers 11, to 1
1n are n baseband signal detectors, and reference numerals 12, to 12n are n outputs. Now, n input terminals 1 to ln are synchronized with each other with a clock period T.
A set of sample values {nose}, {tablet}, ---, {a
n)} (where k=-,...-1, 0, 1, 2...
, ) are added.

Also, the p-th input terminal lp (p=1, 2,..., n)
q-th reception filter 10q (q=1, 2,..., n
) to the input point are expressed as yp, q(t), and the impulse responses of n receiving filters 01 to 1on are expressed as w, (t), w2(t)..., wn(
t). At this time, the received signal xq(t) at the input point of the receiving filter oq is xq(t)=Z Z
atp)・yp,q(t-kT)
...mpni1 is expressed as -.

Here, xq(t) is the desired signal aq)・y
Small q (kT of t-) and interference from other channels p≦
q k (small aip) and ywq (t-kT). Here, if the convolution integral of yp,q(t) and wq(t) is expressed as sp,q(t), then Sp,q(t)=
No yp, q (t・7).

Wq(7)-dcho. ．． ．． ．． ．．
．． (2}, and the output signal y of the reception filter oq
q(t) is expressed by the following equation. yq(t)=k...
a to q)-sq, p(t-kT)+p-row qk)
・sp, q(t-kT)
......Similar to equation {3i○), in equation {3}, the first term represents the desired received signal, and the second term represents the desired received signal. It represents 1,000 moats.

Here, if yq(t) is observed at a certain sample time NT, then yq(NT)=2 atq)-Sp,
q(NT-kT)+p≧qk...atp)・sp,q(
NT-kT), so in order for yq(NT)=a or q), the following equation must hold.

sp, q (mT) = 6 p, q・6 m small (p, q = 1, 2
,...,n m=○, Master 1, Earth 2,...) ・
...{4) However, 6p, q represents the Kronetska delta, and when p = q, 6p, q = 1, and at other times, 6
p, q-0.

■The necessary and sufficient conditions for the formula to hold are given in the above document (2)
Page 2166, 1st $ expression 'As is already known, Mogi...S...(Me-Sheep:)6... ・-----'
5}.

However, Sp, q ('') represents the Fourier transform of sp, q (t). Using the ■ formula, the formula {5) can be expressed as follows. Station) = 6M
---Shelf where Rp, q(na) and Wq(na) represent the Fourier transforms of yp, q(t) and wq(t), respectively.

Equation '6) can be further decomposed into the following equations (7} and ■.≠.
YomuR small (na-ko)wqV-hand)ko1
...・'7) and TofuR...V-Hori)Wq〈Material〉=.

(Wipe sheep q) ----- Shelf formula [7} represents the usual Nyquist first criterion. On the other hand, the formula '8} gives a condition for no interference from other channels at the sampling time at the output point of the receiving filter oq in FIG. If R,,q(na),R2,q(na)``
-..., Rn, q (na) do not overlap each other on the frequency axis, they change the band of Wq (me) to Rq,
qV), the equation {8) is satisfied. This means performing normal frequency division multiplexing without spectrum overlap between adjacent channels. For example, the bandpass filters 5 and 5n in Fig. 1 are replaced with SSB (single sideband) forming filters. If it is evening, the spectrum arrangement of the transmission signal to the transmission path can be expressed as shown in FIG. In Figure 2, “Each SSB spectrum 2
0., 20..., 20n has a wider band than 1 no 2T according to the Nightquist first standard equation.

On the other hand, the orthogonal multiplex transmission system attempts to perform multiplexing in such a way that even if there is spectrum overlap between adjacent channels, equation (2) still holds true. can be given.

That is, in the direct VSB transmission system, bandpass filters 5, to 5n in FIG. 1 are VSB forming filters, and carrier 4 is a cos2 filter. t (or sin2 汀な, t)
, the carrier 42 is set to sin 2 output 2t (or cos 2 output 2t), ... (hereinafter, a channel modulated by a cos carrier will be called an in-phase channel, and a channel modulated by an sm carrier will be called a quadrature channel). ,−
, (1 is 1, 2..., n) = 1'2T. At the input point of the receiving filter 10q in Fig. 1, each VSB spectrum is shaped to be symmetrical with respect to its center. The spectrum arrangement of the transmission signal on the transmission path in this case is expressed, for example, as shown by reference numerals 30 to 30n in FIG. This is clear from Fig. 4. That is, Fig. 4 represents the spectrum of the interference from the adjacent channel at the output point of the receiving filter oq in Fig. 1, and reference numeral 35 indicates the frequency of the receiving filter oq. Characteristic W
q (na), and the reference numeral 36 is the V of the adjacent channel.
The reference numeral 37 represents the interference spectrum after this VSB spectrum passes through Wq(na). qth channel and (q+1)th channel
In the th or (q-1)th channel,
Because those carriers have an orthogonal relationship with each other (
Here, the carriers are in an orthogonal relationship because cos and sin
cos and cos or si
When the q-th channel is demodulated (the relationship between n and sin is said to be an in-phase relationship), the adjacent VSB spectrum becomes oddly symmetrical with respect to the 0 frequency, as shown by reference numeral 36. Therefore, if the filter is set so that the positive frequency component of the interference spectrum indicated by reference numeral 37 is evenly symmetrical with respect to 1/2T, the above-mentioned interference component will satisfy the above-mentioned formula [8]. Become. However, in such an orthogonal VS law transmission system, bandpass filters 5, to 5n are required for VSB shaping as shown in FIG. It has the disadvantage of causing inter-channel interference. In the present invention, VSB shaping is not required, and single-QAM signals are generated and then orthogonally multiplexed.

Next, the principle of the orthogonal multiplex transmission system used in the present invention will be explained.

In FIG. 4, the interference spectrum 37 from adjacent channels is an oddly symmetrical spectrum with respect to the 0 frequency because carriers between adjacent channels have a mutually orthogonal relationship.

If the carriers between these adjacent channels have an in-phase relationship, that is, carrier 4 in FIG.
Connect carrier 42 to cos2 2t (or sin2 bamboo)
2t), . . ., the interference spectrum from the adjacent channel at the output point of the receiving filter oq is expressed as reference numeral 47 in FIG. However, reference number 45
is the frequency characteristic Wq (na) of the receiving filter oq, reference numeral 46 represents the VSB spectrum of the adjacent channel, and the positive frequency components of the interference spectrum 47 are corner symmetrical with respect to 1'2T as in FIG. It is assumed that The interference spectrum 47 is now for 0 frequency,
Since it is even symmetrical, if it continues as it is, the above-mentioned formula (2) will not be satisfied and inter-channel interference will occur. However, here, the input terminals 1, ~ln and the transmitting filters 2, ~2n in FIG.
If a delay circuit of T/2 is inserted between every other circuit (for example, between 1 and 2, between 13 and 23, etc.), then The spectrum becomes a complex spectrum, and its real and imaginary components are represented by reference numerals 48 and 49, respectively, in FIG. 6, and both satisfy the above-mentioned formula {8}. As can be seen from the above, in order to orthogonally multiplex VSB signals, if the carriers between adjacent channels have an orthogonal relationship, it is sufficient to perform orthogonal multiplexing as is, or if the carriers have an in-phase relationship, it is sufficient to perform orthogonal multiplexing. It can be seen that orthogonal multiplexing can be performed with a delay difference of T/2 between channel sample values.

This fact also means that a plurality of QAM signals can be orthogonally multiplexed. The invention is based on this principle. FIG. 7 shows a first embodiment of the orthogonal multiplex signal transmission/reception system and transmission/reception apparatus of the present invention.

In the figure, for convenience of explanation, n is a multiple of 4 (n=4m
), reference numerals 50, .about.50n represent n input terminals, reference numerals 51, .about.51n represent m T/2 delay circuits, reference numerals 52, .about.52n represent n transmission filters, reference numerals 53,
~53n is n modulators, reference numeral 54, ~54n is n
The modulation carrier generators and reference numeral 55 are frequency multiplexing devices that perform frequency multiplexing by adding n modulated signals obtained from the modulators 53, to 53n.

Further, reference numeral 56 is a transmission line, and reference numeral 57, -
57n are n demodulators, reference numbers 58, to 58n
is a carrier generator for demodulation. Additionally, reference numeral 59
, ~59n are n receiving filters, with reference numeral 60
．． ~60n is an n-value baseband signal detector, and reference numeral 61, ~oln are n outputs. moreover,
The carriers supplied from the carrier generators 54, - 51 and the carrier generator 58. The carriers supplied from ~58n are cos2takena, t, and sin2, respectively.
Takena, LCOS 2 lights (na, ten na.)t, Sin2 汀くpu, ten〆. )t,...COS2ke [na. Ten (2h・1)〆. ] t, sin2 汀 [pu, 10 (2h-1) na. ]t. Here, n is any positive frequency and p is any positive frequency. =1/T. In addition, T/2 delay circuits 51, - 51
n is 1, 4, 5, 8, 9,...-, 4k, 4K+1,
..." It is added only to the 4m channel.Here, the frequency transfer characteristics of the transmitting filters 52, ~52n are expressed as (") ~ Hn ("), and the frequency transfer characteristics of the transmitting filters 59, ~52n are
The frequency transfer characteristic of n is R. (na) to Rn (na), and assume that the transfer characteristic of the transmission line 56 is approximately 1 within the band in question (or the frequency characteristic of the actual transmission line is flat at the input point of the receiver). Assume that they are equalized.
) At this time, from the input point of the p-th transmission filter 52p
Transfer characteristic Sp to the output point of the th reception filter 59q
, q(na) are given by the following equation. *． p=2
When kp, q = 2kq or p = 2kp-1, q = 2kq-1 (however, kp, kq are integers that take a value of 1t2), then Sp, q (Na) Kyo-Rq ＜〆）-{H
p [na ten (kp-kq) na.

] 10 days p [na- (kp-kq) na. ]}
...(9)・p:2kp, q=2k
When q-1 or p=2kp-1, q=2kq, Sp
, q(na)=KyoORq(na)-{Hp[naju(kp-k
q) Nah. ] 10 days p [na- (kp-kq) na. ]}
To simplify the explanation, let's consider q=3 (this will be referred to as the third channel) (the following explanation is exactly the same for other values of q). At this time, first, since S3,3(na) gives the desired transfer function for the third channel signal, as already stated, S3,3(na) needs to satisfy the Nyquist first criterion. That is, From expression {7} and expression {9}...
R3 (Me-Sheep) Day 3 (Me-Kyu = 1
Book (11) Also, the obi castle of Day 3 (Na) and R3 (Na) is usually at most Na. Therefore, "The only channels that may cause inter-channel interference are the first, second, fourth, fifth, and sixth channels. In other words, the transfer function that causes the problematic interference is S.' 3.(na), S2,3
Ku〆), S car, 3 Kupu), S room, 3 (Me) and S Ki,
3 (na), and if these all satisfy the above formula (2), there will be no interference from other channels at the sampling time of the third channel on the receiving side. Here, S'
, 3(Me), Sj, 3(Na) and Sj, 3(V) are transfer functions taking into consideration the T/2 delay circuits 51, , 514 and 515, respectively. First, it can be seen that the S car, 3(na), is always 0 and clearly satisfies the formula {8).
That is, S hen, 3 scraps)=KyoR3V)-{Japanese Chi(Me)eI汀〆T-ratio〈Na)e→cloth〆T}=.

Next, S2, 3 (Na) and S6, 3 (Na) are each 3
Ta S2, 3 (Na): Season - R3 (Na) - {Day 2 (Nana).
>-Day 2 (Na Juji.)} S6, 3V) = Gei-R3 (Na)
. Since {day 6 (na-jūna.) - day 6 (na-〆.)}, [R3 (pu)・day 2 (na-〆.)] and [R3 (.
If we make ``)・pine (nana o)] even symmetrical with respect to Na./2, S2, 3 (Na) and S
6 and 3 (na) are both equal to 0. Next, King S, 3 (
n) and S,3(n) are respectively expressed as in the following equations. S'. , 3 no = Mai 3 River {Japanese・V-na.

)e small and small T ten days, (na ten na.) e-i 汀(na, ten na.)
te}=-亥3(na)-e-i Kano T{日・(nā-na.)10日・(hana.)}SI, 3(Ha=One trick R3(na) e「汀〆T{日5〈Me-ten〆.) Ten Buddhas (Me-〆.)}Therefore, [
As long as R3(na)・日,(poona.)] and R3(na)・Hiro(poona.)] are even symmetric with respect to poo/2, then Sヱ, 3(na) and S5, It can be seen that 3(na) satisfies the above formula (2). Therefore, in the first embodiment of the orthogonal multiplex signal transmission/reception system and transmission/reception apparatus of the present invention shown in FIG. 7, Hp (na) and Rp (p) satisfy the Nyquist first criterion, and p and q When different times, it is essential that [Hp(mena.)・Rq(na)] be corner symmetric with respect to ./2. In the above explanation, n transmitting filters and n receiving filters are However, in practical terms, the transfer functions of n transmitting filters and n receiving filters are all the same, and this can be expressed as
, the solution (na) satisfies the first Nyquist criterion, and [day(
If the date (na) is set so that the date (na)] is corner symmetrical with respect to nao/2, the device design can be further simplified.

In addition, in the above explanation, the T/2 delay circuit is
Although this is added only to the 5,...4k, 4k+1,...4m channels, it may also be added only to the 2, 3, 6, 7,..., 4k12, 4k13,..., m11 channels. The essence of invention remains unchanged.

In addition, for convenience of explanation, n=4m, but as long as n is an even number (n=21), the essence of the invention does not change, and the apparatus of the present invention shown in FIG. ,~70
, it becomes possible to transmit and receive one orthogonally multiplexed QAM signal. Therefore, using the present invention,
Without VSB modulation of each baseband channel,
After QAM signals are created in pairs for every two channels, these signals are orthogonally multiplexed, making it possible to perform highly efficient PAM transmission without increasing the scale of the device.

Furthermore, in the present invention, a plurality of VSB signals and a plurality of Q
It is possible to realize an orthogonal multiplexed signal transmission/reception system and a transmission/reception device that can transmit a signal that is orthogonally multiplexed with an AM signal.

That is, if the above-mentioned principle is used, each integer n, m of 1 or more
By orthogonally multiplexing n QAM signals and m VSB signals, it is possible to transmit PAM signals of 10 m) channels. FIG. 9 shows a second embodiment of the orthogonal multiplex signal transmission/reception system and transmission/reception apparatus of the present invention.

In the figure, reference numbers 80 to 806 are six input terminals, reference numbers 813 and 814 are T/2 delay circuits, and reference numbers 82 to 826 are six transmitting filters. Numbers 83 to 836 are six modulators. Further, reference numerals 84 to 846 are six modulation carrier generators, and reference numeral 85 is an upper VSB.
Reference numeral 856 is the lower VSB shaping filter; reference numeral 86 represents the two QNM signals obtained from the above modulator and the VSB shaping filter;
This is a frequency multiplexing device that performs frequency multiplexing by adding VSB signals. Further, reference numeral 87 is a transmission path, reference numerals 88, to 886 are six demodulators, reference numerals 89, to 896 are demodulation carrier generators, and reference numerals 90, to 906 are demodulation carrier generators. are the six receiving filters, reference numeral 91. ~916 are six baseband signal detectors, and reference numerals 92, ~926 are six outputs. Further, the carrier generator 84. ~846
and 89. The six carriers supplied from ~896 are sm2, t, COS2, 2t, and Sin2.
汀〆2t, COS2 汀〆3t, Sin2 汀〆3t, and cos2 product 〆4t, so Pu, 1〆3=〆3-Na2=Na2na,=Ding. [=1/T]. Input end 80
, ~806, there are six PAs that are synchronized with each other with a period T.
The M signal is printed, and the spectrum arrangement of the transmitted signal to the transmission path can be expressed as shown in FIG. That is, in FIG. 10, the reference number 100 is the upper VS motherboard, the reference number 10
1 and 102 are respectively QAM signals, reference numeral 103
represents the lower VSB signal, reference numbers 104-1
07 indicates the frequency position of each carrier. Similar to the above explanation, in the apparatus of the present invention shown in FIG. Transfer function Rq(na) and [Hp(na)・
When Rp (me)] satisfies the first Nyquist criterion and p and q are different, [HPV-o]・Rq (me)] is 〆. /2
By setting even symmetry with respect to , it is possible to perform orthogonal multiplex transmission without inter-symbol interference and inter-channel interference at the sampling time on the receiving side. Also, in this case, as described above, the transfer functions of these 6 transmitting filters and these 6 receiving filters are all the same, and this is defined as ``IH(J)l2.'' Satisfying the first Nyquist criterion, [Sun (Name.), Day (Nago,)] is “
By setting the date so that it is corner symmetrical with respect to o/2, the device design can be simplified. Although the above explanation deals with the case where the upper VSB signal, two QAM signals, and the lower NSB signal are orthogonally multiplexed, in general, n QA
It is clear that the same method can be used to orthogonally multiplex M signals and m VSB signals. However, especially if the upper VSB signal is located at the lower end of the transmission band and the lower VSB signal is located at the upper end of the transmission band, as shown in Figure 10, the deviation of the VSB shaping filter on the transmitting side will cause the difference in the receiving side. can be made less susceptible to inter-channel interference.

As described above, by using the present invention, it is possible to provide a transmitting/receiving signal system and a transmitting/receiving device for orthogonal multiplexed signals that perform PAM signal transmission with a simple configuration and high efficiency, and is extremely effective when used in a data transmission modem device, etc. It is.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing a general PAM signal frequency multiplexing transmission system, and Figure 2 is an SSB diagram showing an example of frequency multiplexing transmission.
Figure 3 is a spectrum diagram showing the spectrum layout in a conventional orthogonal VS bus transmission system; Figure 4 is a spectrum diagram showing how inter-channel interference disappears in a secondary orthogonal VS separate transmission system; 5 and 6 are spectrum diagrams for explaining the principle of the present invention, FIG. 7 is a block diagram showing a first embodiment of the orthogonal multiplex signal transmission/reception system and transmitting/receiving apparatus of the present invention, and FIG. 8 is a diagram showing the spectral arrangement of the transmission signal in the device of the present invention shown in FIG. 7, FIG. 9 is a block diagram showing a second embodiment of the orthogonal multiplex signal transmission/reception system and the transmitting/receiving device of the present invention, and FIG. 9 is a spectral layout diagram of a transmission signal in the device of the present invention shown in FIG. 9. FIG. In FIG. 7, reference numerals 51 to 51n are T/2 delay circuits, reference numerals 52 to 52n are n transmission filters,
Reference number 53. ~53n is n modulators, reference numeral 54
, ~54n are n modulation carrier generators, reference number 5
5 is a frequency multiplexing device, reference numerals 67 to 57n are n demodulators, reference numerals 58 to 58n are n demodulation carrier generators, and reference numerals 59 to 59n are n reception filter generators. Reference numerals 60, to 60n are n baseband signal detectors. In FIG. 9, reference numerals 813 and 814 are T/
2 delay circuit, reference number 82. -826 are six transmit filters, reference numbers 83 and -836 are six modulators, reference numbers 84 and -846 are six modulation carrier generators, reference number 85 is an upper VSB shaping filter, Reference number 85
6 is the lower VSB shaping filter and reference numeral 86 is the frequency multiplexer. In FIG. 10, reference numeral 10 represents the upper VSB signal, reference numerals 101 and 102 respectively represent the QAM signal, and reference numeral 03 represents the lower VSB signal. 2 figures, 3 figures, 4 figures, 5 figures, 6 figures, 7 figures, 8 figures, 9 figures, ○ figures

Claims (1)

[Scope of Claims] 1 Baseband pulse amplitude modulation signals of 2N channels synchronized with each other with a clock cycle of T seconds are generated when the frequency difference between adjacent carriers is 1/T cycle and each carrier is in phase or orthogonal to each other. In the orthogonal multiplex signal transmission/reception method, in which the signals are converted into N orthogonal amplitude modulated signals using 2N carriers whose phases are set so as to maintain the same, these signals are multiplexed and transmitted. and at the identification time of each baseband signal demodulated on the receiving side by giving a delay difference of T/2 seconds between the corresponding transmitting side baseband pulse amplitude modulated signals only for two orthogonal channels. An orthogonal multiplex signal transmission/reception system characterized by reducing inter-symbol interference and inter-channel interference to almost zero. 2 A quadrature amplitude modulation signal and a quadrature amplitude modulation signal or quadrature amplitude modulation for each of two adjacent carrier frequencies f_K_-_1 and f_K (f_K>f_K_-_1) whose phases are set so as to maintain an in-phase or quadrature relationship with each other. When the signal and the lower vestigial sideband signal or the upper vestigial sideband signal and the lower vestigial sideband signal or the upper vestigial sideband signal and the quadrature amplitude modulation signal correspond to each other, the two carrier frequencies f_K and , f_K_-_1, and the upper vestigial sideband signal and the upper vestigial sideband signal or the lower vestigial sideband signal for each of the two carrier frequencies f_K_-_1 and f_K. the two carrier frequencies f_K and f_K_- when the signal and the lower vestigial sideband signal or the quadrature amplitude modulated signal and the upper vestigial sideband signal or the lower vestigial sideband signal and the quadrature amplitude modulated signal respectively correspond. If the difference from __1 is 1/2T cycle and the quadrature amplitude modulation signal corresponds to a certain carrier frequency f_1 or the upper residual sideband signal and the lower residual sideband signal correspond simultaneously, sin2πf_Kt and cos2πf
_Kt, otherwise s
One carrier, in2πf_Kt or cos2πf_Kt, is used, and a total of (2N+M) carriers are used to synchronize each other with a clock period of T seconds (2
N+1M) channel baseband pulse amplitude modulated wave is converted into N orthogonal amplitude modulated signals and M vestigial sideband signals, and then these are multiplexed and transmitted. In the frequency domain 2 adjacent to each other in
Each baseband signal is demodulated on the receiving side by giving a delay difference of T/2 seconds between the corresponding transmitting side baseband pulse amplitude modulated signals only for two in-phase channels and two orthogonal channels. An orthogonal multiplex signal transmission/reception system characterized by reducing inter-symbol interference and inter-channel interference to almost zero at identification times.