JPS58114530A - Transmitter of broad band signal with plural divisions - Google Patents

Abstract

PURPOSE:To transmit a broad band signal as a plurality of narrow band signals, by sampling the broad band signal with a plurality of signals having high frequencies and phases shifted by a prescribed interval, transmitting the signals, and synthesizing the signals with the same signals by sampling. CONSTITUTION:An original signal Si(t) and an output signal b(t) transmitted via a transmission line 13 of bands 0-omegas/2 are applied to sampling circuits 11, 12 at transmission and reception sides. Sampling signals g1(t), g2(t) are applied to the circuits 11, 12 and the signals Si(t), b(t) are sampled. This sampling signal is a sampling signal having the angular frequency omegas and a phase different by 180 deg.. Outputs a(t), c(t) of the circuits 11, 12 are applied to the transmission line 13 and a demodulation post-processing section 14, which is the process of reproduction on a cathode-ray tube by means of the integration effect of visuality, and an S0(t) is its output signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a device that divides a wideband signal into a plurality of parts on a transmitting side and transmits them as narrowband signals, and combines the divided signals on a receiving side to reproduce a wideband signal. .

Technical background of the invention and its problems For example, in order to perform broadband recording and playback in video tape recorders (hereinafter referred to as VTRs), technology has been developed to increase the running speed of the tape and increase the magnetic density of the tape. is considered. However, when changing the tape running speed, compatibility with existing devices becomes an issue. At the current stage, it is still difficult to increase the magnetic density. Therefore, as an alternative technique, a multi-head system is being considered in which a wideband signal is divided into narrowband signals and the signals are recorded using a plurality of heads.

However, even in this case, the wideband signal is divided and transmitted,
The technology required to combine these divided signals has not been established, and the development of this technology is highly desired.

Purpose of the Invention The present invention was made based on the above circumstances, and its purpose is to divide a wideband signal and transmit it as a plurality of narrowband signals, and to combine the plurality of narrowband signals to generate a wideband signal. It is an object of the present invention to provide a multi-divided transmission device for a wideband signal that can be reproduced.Summary of the Invention This invention samples a wideband signal with a plurality of sampling signals having a higher frequency and whose phases are shifted by a predetermined interval. However, it is transmitted as a plurality of narrowband signals, and the transmitted signals are sampled with the same sampling signal as described above and then synthesized to reproduce a wideband signal.

Embodiments of the Invention First, horizontal interlaced scanning, which is the basic principle of the invention, will be explained. In this horizontal interlaced scanning, a wideband signal, such as a video signal, is sampled using a sampling signal that is synchronized between the sending side and the receiving side, and the phase of this sampling signal is changed every frame (in the case of sequential scanning, the field period is one frame period) by 2π. /N (N is the interlace ratio of horizontal interlaced scanning, N:1 interlace).
Complete one frame of horizontal interlaced scanning with frames,
This compresses the transmission band to 1/N.

Here, the principle of horizontal interlaced scanning of black and white television signals will be explained for the case where N=2. FIG. 1 is a block diagram showing the principle. In the figure, 11 and 12 are sampling circuits on the sending side and the receiving side, respectively. This circuit 1
1.12 are transmission lines 13 for the original signal (video signal) S, (t) and the band O~ω, /2 (ω is the angular frequency), respectively.
The output signal b(t) of the sampling circuit horn is supplied via the sampling circuit. Moreover, this sampling circuit 11 e12 has sampling signals gt(t), gz
(t) and said signals 5i(t) and b (t
) are sampled. This sampling signal gt
(t), gz (t) #-j: Sampling signals with 1806 different angular frequencies ω and phases, which are switched every frame. The sampling circuit 1.

The 12 output signals a(t) and C(1) are respectively supplied to the transmission line 13 and the demodulation post-processing section J4. This post-demodulation processing section J4 is a reproduction process based on the visual integral effect on the cathode ray tube, and 5o(t) is its output signal. Here, 5o(t) is a signal after a frame period of T seconds and the original signal are added together due to the visual integration effect, so S (t) = CI (t T ) 100 (1)
・・・・・・・・・(1-1) CI (t): odd number 0)
Signal Cx (t) in a frame: There is a process of signal in even number (N+1) frames, but if the correlation between frames is extremely large and the visual integration effect is perfect, (
1 Knee 1) Replace 0ct(t T) with Ct(t) in the formula to obtain . Therefore, FIG. 1 can be replaced as shown in FIG. 2. Note that 2 in FIG. 2 is an adder sb in place of the demodulation post-processing section J4, and other parts that are the same as in FIG.

5- Here, let the sampling signal gl(t)2g*(t) be an impulse with a repetition angular frequency ω8. The Fourier series of a square wave is given by the following equation.

・・・・・・・・・・・・(1-2) In the case of an impulse, since the limit of τ/T → 0 in equation (1-2), (however, n is finite), the sampling signal By substituting the above conditions into the equation g1(t)Fi(1-2), it is expressed as follows.

g t (t) = 2 10ccsωgt10ool! 2ω
, +1...)-"-" (1-3) On the other hand, g-to(1)
has a 180° phase difference from gx(t), so (1-3)
By substituting (1--) for tK in the equation, it is expressed as ω8 in the following equation.

61 = K (interval axis (ω, 1π) transponder (2ω1It-2π) +・
...) Here, the operation of the sampling circuit 111rl12 is based on the original signal and the sampling signals g1(t), gt (
t), so this circuit 1 no 1 ・1 no 2
The output signals a1(t) and ax(t) are as follows.

If the angular frequency of the original signal is ωb (ωBffllLX≦ω8), then equation (1-5) is expressed as follows.

The spectrum of equation (1-6) appears as shown in FIG.

In the figure, Bl * 82 + Bl are ω8 and 2, respectively.
It is a sideband wave of ω13w m. ILI (t), al
The frequency of the spectrum of (t) is the same, but C8's 01ll Teiwa (ω, -ωb).

The phase of (C8+ωb) is reversed.

Next, the output signals bl(t) and bx(t) of the transmission lines 131 and 13 (reduction filters) become K as follows depending on the angular frequency of C5. (Low-pass filter cutoff frequency = -9 - 7 = As is clear from equation (1-6), when C5 ωll/2, bl(t) and bt (t) are in phase, to/2〈C5〈
At C9, the phase is reversed.

Next, bl(t) and bl(1
) is sampled on the receiving side, the signals C1(t) and C2(t
) is removed as shown in the following equation.

9- 8- 10- Therefore, if C1(t) and C2(t) are combined with adder 2 and components of 03 and above are removed, 50(t) becomes 0, C5, C8. The original signal S,(t) of the range can be reproduced.

FIG. 4 is a spectrum diagram of each part of FIG. 2, and is represented by a phase amplitude spectrum with polarity added to show the power of the conversion process. Also, the original signal S, O~ in (t)
The spectrum of 7L2 to ω is marked with the symbol (A), and the spectrum component of 7L2 to ω is marked with the symbol (A).

Furthermore, the dotted line indicates the sampling circuit 'j1ml1' on the sending side.
The one-dot chain line is the sideband wave due to ω in the part (g) of the transmission signal, and the two-dot chain line is the sideband wave due to ω in the part (a) in the transmission signal. Here, as shown in the spectrum diagram, it can be seen that the frequency component (7) from 0 to -1 is transmitted as a baseband signal as it is in the sampling and low-pass filtering processes. On the other hand,”~ω2I! The frequency component (A) is the sampling circuit JIH on the sending side.
*21x converts the lower sideband of C8 into the region O to t, and the receiving side sampling circuit 121 *122 converts C8 again.
The signal is returned to the region of ω8 as a lower sideband wave of ω3 and is reproduced.

Sideband components other than the above are self(
1) and CI(t) have opposite polarities and cancel each other out, producing an output signal S. (1) It does not appear inside.

The above is the principle of band compression by horizontal interlaced scanning when l'Q=2. In addition, in the mathematical proof and spectrum diagram, all the sideband components of 2ω8, 3ω, etc. are omitted, but since 0, C5, and C8, that of the sampling circuit on the sending side is a higher component than C8. In addition, it is removed by a low-pass filter, and also by the receiving side sampling circuit 121.

Similarly, since the frequency component of the transmission signal is 0 to 1, the 2ω sideband generated at 12 is a component higher than 100ω8 and can be removed by a filter after synthesis, so it does not have any influence.

Next, the principle in the case of N=4 will be explained.

Although it is slightly more complicated than the case where N=2, the idea is the same. In this case, the sampling signal is gx(t)・gz
(t)1gs (t), and g<(t), and their phases differ by 2π/N = π/2, respectively.

That is, gx (t) = K (10 μs ω in ovary 2 ωllt 10 times 3 ω, t-1 - cos 4 ω s1 +... river) g2 (t) = gx (t-7) = K (7 + in ω 8 t co
s2ωtsin 3ω, t + cos 4ω, t+
... song) g3(t) = g+ (-π) = K(2as
ωt+cos2ω is one bunch 3ωst +cos 4ω, is 10...)g4 (t)= g+ (t-4π) =K
(' sinωt, cos2ωt2 2
I! +, gln3ω, t +cos 4ω, t+・song・)
・・・・・・・・・・・・・・・・・・・・・(2-1
)13- and the input original signal is sinωb(t), then sin7''
IJing output signal a1(t) is JLI(t)=K-sinωbtagl(t)=%
(51(lωbt15tn(ωb-ω,)t+5fn
(ωb−ω,)t+5in(ωb=2”,)t
+sln (ωb+2ωll) 1 +−−−−−−)
・・・・・・・・・・・・・・・・・・・・・ (2-
2). Other values am(t) to aa(t) are calculated in the same way, and the results are shown in Table (2-1).

14- -15- Further, the output signal of the low-pass filter (pass band O-pot ωll) becomes the following four signals depending on the value of ω5.

(7) Okuω5ku: ω5 component) ω, Kuω5ku ω, : (ω, -ω8) component 16- 17- Also, the sampling output signal C(t) on the receiving side is Cn as described above. It is given by (t)=bn(t)×gn(t).

The gn(t) obtained from the above formula (2-1) is shown in Table (2-3)
Shown below.

Table (2-3) Sampling output signal g (t) C(t)
is b (t) given by the above equation (2-2) and table n

It is given as the product of gn(t) given by n(2-3). Here, ω, kuω
Table (2-4) shows the calculation results for the case of 5<-Hω.
Shown below.

18- As seen from Table (2-4), when ω8×ωゎ〈Σω8, the output signal S (t) is as follows.

+ cos (ωb-ωIrit-m1nω8t+m1n
(ωb-ω,)t”cas3ω3t-cos(ωb-ω
s)t'5(n3ω,i)・・・・・・・・・・・・
... (2-3) (4ffls-ωb)〉2ω1
Therefore, the component in the furnace LPF with a cutoff frequency of 2ω is removed, and the output signal S 0 (t) becomes 2 S o (t) −2·sinωbt . By performing similar calculations for ω in other frequency regions! The component in the 2-number region in the frequency range of 0 to 2ω8 of DS0(t) is −·sinωbt.

Next, an embodiment of the present invention based on the above principle will be described with reference to FIGS. 5 to 7.

FIG. 5 shows the configuration of the sending device when N=4. The wideband original signal 5t(t) is, for example, an image P shown in FIG. 7 converted into a video signal by a television camera or the like. Image P is the highest frequency (fbmax) of the video signal
White (G) and black (B) pixels corresponding to 1 are arranged in a grid pattern in the horizontal direction. These original signals S, (t) are supplied to sampling circuits 511-514, respectively.

These sampling circuits 511 to 614 include a sampling signal generator 52 and a sampling signal generator g1(t), g(t)1gs(t)9g<(t
) are supplied respectively. This sampling signal gl(
t) to gt(t) are signals with frequencies f, respectively, and the sampling signal frequency fs and the original signal S
, (t) and the highest frequency fbm a x is f8≧
-K fbmax ・・・・・・・・・・・・
・・・・・・・・・(There is a 3-D relationship. Also,
The sampling signals g-t(t) to g4(t) are each 0. π/2. They have a phase relationship of π and 3/2π, and gl(t) to g4(t) are (M-)-1)2, respectively.
This is a sampling signal of the 1-th to (M+4)th (M:0, 1.2, . . . ) frames. Note that when the original signal is a television signal, a sampling signal is generated from a synchronization signal or the like. Moreover, gl~4(t) shown in FIG. 7 is a signal obtained by combining these signals. The original signal sampled with such sampling signals gl(t) to g4(t) is processed by a low-pass filter LPF 5 whose passband is O to ff.
J l ~534, respectively. This filter is Of.

(excluding f) may be used. This filter s
The output signals bx(t) to b4(t) of 31 to 534 are the seventh
As shown in the figure, odd-numbered frames have a white level and even-numbered frames have a black level.These filters 531 to 534
The output signals of are supplied to transmission lines 541 to 544. By the way, the signal band fc in this transmission path s41 to s544
is the formula (3-1) above. -f-8fbmax・・・・・・・・・・・・(
3-2) It has a band of 1/4 compared to the original signal of 0 2 8.

22- Note that the transmission path referred to here is a modulation/demodulation device (AM, FM, PM, PCM, etc.) for transmitting a baseband signal onto a high frequency transmission path (wired, wireless, VTR, etc.).

It includes digital modulation such as PSK.

On the other hand, the narrowband signals transmitted through the transmission lines 541 to 544 are processed by sampling circuits 611 to 611 of the receiving device shown in FIG.
614 respectively. This sampling circuit 6
The same sampling signals gl(t) to g4(t) are supplied to the sampling signal generator 62 and the sending-side sampling signal generator 52 to 1z to 614,
The transmitted signals gl(t) to g4(t) are sampled. For synchronization of the ring signal generators 52 and 62, well-known means such as adding a synchronization signal to the sampled signal on the sending side, detecting this on the receiving side, and controlling the generator 62 are applied. The sampling circuit 61. The output signals -(1) to C4(t) of -614 are combined by a combining circuit 63, and this combined output signal is supplied to a low-pass filter LPF 64 with passbands 0 to f, max. Therefore, the output signal of this filter 64 -IS. (1) is a reproduction of the original signal s, (t) as shown in FIG. Further, FIG. 7@(1) shows the display state of a cathode ray tube when, for example, Cx(t) to C4(t) are supplied to the cathode ray tube, and the image P is reproduced by the visual integration effect.

Note that while the N:1 horizontal interlacing can reproduce the original signal in N frames, the frame frequency does not decrease in divided transmission. Since this is transmitted using N transmission paths with a band of 1/N fb max, the total transmission bandwidth is N x - f max = fb max b, which is the bandwidth necessary to transmit the original signal. It is clear from the fact that

Effects of the Invention As detailed above, according to the present invention, a wideband signal can be divided and transmitted as a plurality of narrowband signals, and a plurality of narrowband signals can be combined to reproduce a wideband signal. Therefore, it is possible to provide a multi-division transmission device for wideband signals suitable for devices handling wideband signals, such as VTRs.

[Brief explanation of drawings]

1 and 2 are configuration diagrams shown to explain the invention in detail, FIG. 3 is a spectrum diagram of FIG. 2, FIG. 4 is a spectrum diagram of each part of FIG. 2, and FIGS. FIG. 6 shows an embodiment of the wideband signal multiple division transmission device according to the present invention, FIG. 5 shows the configuration of the sending device, FIG. 6 shows the configuration of the receiving device, and FIG. 511-514 +611-614...sampling circuit, 62.62...sampling signal generator s
5J 1 'S J 4 + 64...Low pass filter, 541-544...Transmission line, 63...Synthesizing circuit. Applicant's representative Patent attorney Takehiko Suzue 25- 22 Figure 1, Figure 2, 9, (t) q, (t) ffia, (!b, (t)! + C1 (, t) Figure 4, 5.1 "Z-74, finished" m5o.-Fig. 5, Fig. 6, 54, 61+ 63c+
(t) Ring Wolf & 641
cL”k g, (t) Enclosure 54.12
””(“)口LPF ”〉7° 傛 訃4″″”
92 (t) mouth ゝ43 Iyosako□, Sun 7″ link ゛544 ”3 (t) mouth fishing t) Iyon path gun Gan 761 non-7 circuit t) c4 (t) Fig. 7

Claims (1)

[Claims] means for generating sampling signals whose phases are higher than the highest frequency of the original signal and separated by a predetermined period, and means for sampling the original signal with the sampling signal supplied with the same broadband original signal. a sending device comprising narrowband transmission means for respectively transmitting data; means for generating the same sampling signal in synchronization with the sampling signal generation means; 1. A multi-divided transmission device for a wideband signal, comprising: a receiving device comprising means for sampling the sampled signal, and means for synthesizing the sampled output signals and reproducing the wideband original signal.