JPS63269881A - Television signal transmitting system - Google Patents

Abstract

PURPOSE:To double the resolution of a monitor recording or the like by dividing a TV signal to be transmitted to n channels by a 1/n sub-channels and respectively transmitting in a frame sequence. CONSTITUTION:A TV signal waveform to be recorded is sampled at the one cycle Ts of a Nyquist sampling frequency fs on a time base and further sub- sampled and divided into two channels A, B every other sampling. At this time, a base band component (solid line), the frequency fs and side band components (dotted lines) in the upper and lower parts thereof are generated. It is further sampled at fs/2 in the signal spectrum of the respective separated channels, so that the frequency of the fs/2 goes to a new sampling frequency and the side band (chain line) is generated. Such both channel signals A, B are transmitted in a general analog transmission path. In such a way, at the time of a reproduction, the upper and lower side bands of the fs/2 are different in phase by 180 deg., so that they can be cancelled and the absolutely same signal at the time of a source sampling can be reproduced.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is directed to transmission channels and recording devices having a narrower band than the required transmission bandwidth given by the television system in television signal transmission or television signal recording. It relates to a system for transmitting or recording full-band television signals to equipment, especially the so-called VH3 system - a small and inexpensive VTR such as a VTR.
The present invention relates to a television signal transmission or recording method suitable for monitoring television recording using TR.

[Conventional technology]

Television signals have a signal band of 4 Mllz or more, and it goes without saying that the same band is required for recording. , C separation, and a luminance channel in which the Y signal is flat up to about 2 M llz, with a significant response drop (more than 10 dB) at 3 M llz, and a chromaticity channel that can pass the carrier chromaticity signal at about ±500 k Ilz. This level of V
TR is used for recording surveillance television, but the band, especially the luminance signal band, is insufficient.

For surveillance recording, a VTR specially designed for surveillance, called a time-lapse VTR, is generally used, but the signal system is almost the same as that of the VHS system to VTR mentioned above, and the resolution is almost the same. It is.

[Problem to be solved]

As mentioned above, even if the TV signal has a resolving power of 4.2 to 4.5 MHz, the resolution will drop to about half when recorded on a VTR, so it is difficult to detect the criminal in security monitoring records. Even if the crime is recorded with a camera and recorded on a VTR, it is often impossible to identify the perpetrator's face due to the lack of resolution.

The purpose of the present invention is to process and transform the signal itself even if a VH3 system-VTR is used.
The purpose of the present invention is to provide a method for obtaining a resolution of z or more, thereby doubling the resolution of monitoring records, etc.

[Means for solving problems]

In order to achieve the above object, the present invention provides an arbitrary natural number n
Regarding this, the television signal to be transmitted is divided into n channels by 1/n sub-samples, and each divided part is transmitted in frame sequence.

That is, the television signal transmission system of the present invention includes the following means.

■ Source sampling means for sampling the television signal to be transmitted at a frequency twice or more than its upper limit frequency.

(2) Subsampling means for subsampling each of the plurality of consecutive samples of the output sample string of the source sampling means into a plurality of parts, and dividing it into signals of a plurality of channels.

(2) means for rearranging the plurality of outputs from the sub-sampling means on the time axis and transmitting them channel by channel in a time-division manner every scanning period of a television scanning system;

(2) Means for controlling the phase of the source sampling by obtaining PLL phase information from the subsampled results.

- Monitoring recording on the FG is done frame-by-frame, like a time-lapse VTR, and there is no need to record a complete video. In such cases, one frame of the human input signal to be recorded is divided into two frames, the band is reduced to half, and recorded, and later they are combined to restore the original wideband signal. By repeatedly sending out broadband frames twice, there is no problem even if only 15 frames of information can be recorded per second regarding movement.

Furthermore, in the analog transmission method of subsampled signals, as is well known among those skilled in the art, it is required that the sampling phase at the receiving end be exactly the same as the subsampling phase at the transmitting end. However, the present invention provides a new method that is particularly effective in this regard with hour wheels.

[Effect]

According to the present invention, it is possible to record and reproduce the entire band using only the brightness channel of VH3-VTR, etc., without dropping frames and separating the NTSC television signal into Y and C.
For applications that do not require smoothness of movement, such as monitoring recording, an inexpensive recording device with excellent definition can be provided, and its practical effects are extremely large.

In addition, it is possible to record and play back so-called high-definition television signals with more than 1,000 scanning lines using the frame-drop method, making it possible to record and play back so-called "background pictures," which mainly consist of still images and high-fidelity music, at low cost. It will also be provided.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail using the drawings.

FIG. 3 is an explanatory diagram of signal sampling according to the present invention, and shows, as an example, a case where the number of channels is n=2. The TV signal waveform to be transmitted or recorded, shown by the solid line, is sampled at one period T3 of the Nyquist sampling frequency on the time axis, and further sub-sampled and divided into two channels, A and B, at every other sampling. do. The resulting spectrum, as shown in Figure 4, shows that if Nyquist sampling is used, the original television signal component, that is, the baseband component, is shown as a solid line in Figure 4, and the sampling frequency fs and dotted lines above and below fs. A sideband component shown by appears. Needless to say, similar high-order spectra, ie, repeat spectra, appear at frequencies that are integral multiples of rs, but they are omitted in FIG. As shown in Fig. 3, in the signal spectrum of one channel separated into two channels A and B by subsampling, it is further sampled at r s / 2, so f s /
The frequency No. 2 becomes a new sampling frequency, and sidebands as shown by the dashed line in FIG. 4 occur, and rs and its upper and lower sidebands become second harmonics.

The important point here is that, as shown in Figure 3, the subsampling phase differs by 180 degrees in both channels A and B, so the sideband of f s / 2 also has a phase difference of 180 degrees in both channels A and B. The difference is that Therefore, A
, B, by transmitting the signals of both channels using a general analog transmission path and resampling them at the source sampling phase and the normal phase, and rearranging them into one sample sequence again. The upper and lower sidebands cancel each other out, and reproduce exactly the same signal as when sampling the source, including the baseband component and the upper and lower sidebands of fs, and more precisely, the repeated spectrum at integral multiples of fs. I can do it.

It is obvious that this holds true not only for the two channels A and B, but also for any n channels. Using the digital frame memory originally used in machines and home VTRs, the data is transmitted in frame sequence with a necessary amount of delay. For this reason, the signal waveform on the transmission line takes exactly the same form as a general television waveform, leading to the characteristic that transmission lines and VTRs that already exist in the world can be used as is.

By the way, as mentioned above, many of the home VTRs that are already in widespread use separate the NTSC signal into a luminance signal component and a chromaticity signal component, record them according to their characteristics, and separate and record the signals before outputting them. The luminance and chromaticity signals are synthesized and sent out as before, but the luminance signal band is approximately flat up to about 2 MHz, as shown by the solid line in Figure 5, and above that it slowly attenuates to about 3 MHz. It enters the cutoff range between .2 and 3.3 MHz. Therefore, the frequency of 50% amplitude of the upper limit of the passband is around 2.5 MHz, and Is should be selected so that the lower side hand of fs/2 is folded with respect to the baseband at this frequency.

Then the subsampling frequency is about 5.3M! Iz, and fs is around 10.7 MHz. This fs is NT
Since the frequency is almost triple the frequency of the SC color subcarrier, by selecting Is exactly three times the frequency of the color subcarrier and performing coherent sampling, the color burst can be used for sampling phase control, and the whole can be made extremely inexpensive. I can summarize it.

This point is the most noteworthy point in the present invention.

The frequency components that are actually recorded and reproduced are only the baseband component shown by the solid line in Fig. 5 and the part of the lower side wave of f s / 'l shown by the dotted line within the VTR luminance channel band. The component indicated by the dotted line is attenuated at f s / 4 or more for the baseband component, whereas r s 74
The above components are folded at a frequency f s /4 to become a folded signal, and the frequency spreads in the lower direction.

Next, the present invention that has been described so far will be specifically explained based on the embodiment of the signal processing system shown in FIGS. 1 and 2.

FIG. 1 is a block diagram of a pre-signal processing system for pre-processing a signal to be recorded prior to recording. Although the principle is the same for the PAL system, the NTSC case will be explained here.

The input signal is input to a sampling circuit l with a sampling frequency f
After being source sampled at s and subsampled at 8.B switch 2, the B signal is delayed by one frame at frame memory (digital frame memory, etc.) 3, and assembled into a frame sequential signal at a and b switches 4. Furthermore, an ID pulse (identification pulse) indicating the contents of the assembly is added by an ID adding circuit 5, and the result is supplied to the VTR input.

On the other hand, a part of the input signal is synchronously separated by the synchronous separator 6, resulting in a composite synchronous signal (MS), a burst gate pulse (BF
) occurs. 7 in the figure is a variable frequency oscillator (6XfscV C
O), the oscillation output is divided by two by the first frequency divider 8 and then supplied to the sampling circuit 1.
The frequency divided by two by the frequency dividing circuit 9 drives the A and B switches 2.

A part of the output of the second frequency divider 9 is divided by 3 by the 3 frequency divider 10, and the gate pulses corresponding to the 0th, 1st, and 2nd phases of the frequency division by 3 are applied to the next stage. The signal is supplied to the gate circuit 11. The gate circuit 11 is also supplied with an f s / 2 clock and a burst gate pulse (BP), but in this circuit, the f s / 2 clock is supplied with 3
Gate with a triple gate pulse from the frequency divider circuit 10,
Furthermore, a triple pulse pulse gated with a burst gate pulse is generated, and #0 circuit 12, #1 circuit 13, #2 circuit 1
Send to 4. The #O, #1, and 62 circuits are a type of memory, and in the case of a digital circuit, a register is used, and in the case of an analog circuit, a sample holder is used. The inputs of these three memories are subsampled signals, and since the gate circuit 11 outputs a triple pulse pulse only during the burst period, the #0, #1, and #2 circuits receive subsampled signals. Sample values for each triplet unit of the burst are accumulated.

The accumulated burst triple time sample values are #
1 and #2 are arithmetic averaged in an arithmetic averaging circuit 15, and subtracted by #0 in a subtracting circuit 16, resulting in a PLL control signal that controls the frequency of a variable frequency oscillator (6XfscVCO) 7.

As a result, in the sample phase #0, the instantaneous value of the sub-sampled burst sine wave always coincides with the zero cross point where it changes from positive to negative and becomes stable.

The situation will be explained with reference to FIGS. 6 and 7.

That is, FIG. 6 shows the source sampling and A and B subsamples of the burst part during pre-processing of a recorded song, where the solid line is the sine wave of the human burst signal, and the dotted line is the sine wave of the burst subsampled to the B channel. , furthermore, the B sample string is #0. #1 and #2 are dealt with sequentially.

No. 71 shows an explanation of sampling pulse phase control using a Hector diagram, #O, #1. For each of #2, for the burst phase error φ, #0=8Q+3in(φ +
π), tll=AO+5in(φ-π/3),
Since #2=8Q+5in(φ+π/3), subtracting #0 from the arithmetic average of #1 and #2, we get (ltl+#2)/2-1tO=(AO+5in(φ-
π/3) +AO+5in(φ+ff/3))/2-(
AO+5in(φ+π))・AO+0.5・5i
n(φ)-AO+5in(φ), 1.5・5in(φ), so 5in(φ) ~ φ, regardless of AO, that is,
Since a signal proportional to the phase error can be extracted, it can be effectively used as a PLL error signal.

However, it should be noted that the phase of the burst sine wave differs by π for each IH, so the output of the divide-by-3 circuit 10 also runs at the same frequency and phase as the burst, and horizontal synchronization is achieved between adjacent scanning lines. If you look at the signal as a reference, the same thing will be repeated with a phase shift of half a cycle of the burst sine wave. Since this point is exactly the same as that of the PLL circuit of a general color receiver, it is easy to understand that the operation as PLL phase control is also partially the same as that of a color receiver.

The state of the frequency divider circuit 10 etc. by 3 is unknown depending on the conditions when the power is turned on, but it is sufficient as long as the fs/2 phase matches the sample phase in the pre-recording pre-processing and the post-reproducing post-processing. Therefore, even if the initial value of the frequency divider circuit 10 deviates, as explained above, the convergent light of the PLL loop will always be the same as the PLL for pre-processing before recording and the PL for post-processing after reproduction.
L also becomes the zero crossing point of the subsampled burst sine wave going from negative to positive.

The explanation returns to Figure 1. The switching and ID signal generation circuit 17 first commits the first source sampling of the frame to be transmitted as a subsample to A1 order as B, and performs composite synchronization (M
S) and the output of the second divide-by-2 circuit 9 to the A and B switches 2
It is determined which one should start from, and the A and B switch pulses are supplied to the A and B switches 2. The second is I
For the D signal, the signal indicating the content of the frame is vertically blanked, for example, using the 20th IH period, and the special shooting of the a signal (0-IRE unit date of the TV signal, 1 for the b signal)
By superimposing pulses (80-100-IRE units of the television signal), a.

b as a frame cycle synchronization signal, and a after playback.

It is used for control to assemble b-frames into one complete frame signal without error.

The reproduced signal from the VTR is subjected to the processing shown in the block diagram of the post-reproduction signal processing system shown in FIG. 2 to restore the original wideband signal. That is, the reproduced signal is resampled by the sampling circuit 18 and stored in the frame memory 19.
The A and B switches 20 driven at a frequency of f s / 2 combine the one-frame delayed frame and the undelayed frame into one frame, and then repeatedly send out the combined frame for two consecutive frames. ID that is repeated twice in the frame repeat circuit 21 and is unnecessary externally
The signal is removed and sent to the output.

゛ Regarding clock generation and sample phase control, the sampling phase for pre-signal processing is the same (by using the same circuit, the sampling phase for post-processing is also the same. Therefore, the same sign as the previous one is used. The components indicated by the numerals have the same configuration and operation as the pre-signal processing system shown in FIG. 1, and to avoid repeating the same explanation, the explanation of this part will be omitted.

What is different from the prior signal processing system is the I by the ID detection circuit 22.
D detection and control based on the detected results.

First, the frame-sequential ID pulse superimposed on the 20th H indicates the a signal when it is zero, so it is a frame that should be stored in the frame memory 19, and the frame repeat circuit 21 is a frame that should repeatedly send out the previously sent frame. be. When it is 1, it is the b signal, so frame memory 1
The frame-delayed output of the a signal from 9 and the b signal from A and B
Switch 20 is used to indicate when the original sampling sequence should be restored, and frame repeat circuit 21 is set to A.

The output of the B switch 20 is sent out as is, and at the same time, it is stored in the frame memory 19 in preparation for sending out the same signal in the next frame.

Another point is that in order to make the initial conditions of the A and B switches 20 the same as those of the recording unit pre-processing, A.

The B discrimination circuit 23 detects the polarity of the output fs/2 of the second divide-by-2 circuit 9 at the frame start, and selects the A and B switches based on the agreement with the pre-processing side to initially use the A signal. This is to set the initial conditions of the control signal.

Although omitted in Figures 1 and 2, it goes without saying that in order to apply digital frame memory, an A/D converter is required for the input of the frame memory 3゜19, and a D/A converter is required for the output. It does not matter whether the other parts are constructed digitally or analogously. The important things are: 1) sample the source, 2) divide it into two channels by 1/2 subsample, and 3) record the divided two channels in frame sequence.

4) In order to make the subsample phase after reproduction exactly the same as the sample phase of preprocessing, a sample phase control signal is obtained from the subsample output in both preprocessing and postprocessing.

That's true. As can be seen from this explanation, except for 3), 1), 2), and 4) can be constructed by analog, and it is easy to understand that according to the present invention, in particular, item 4) has the feature that it can be constructed by analog. be done.

According to the signal processing explained in Figs. 1 and 2, the frequency of the color subcarrier is 0.75 times (about 2.7 Mfiz
) The components below are transmitted as they are Haasband components, and the higher frequency components are transmitted at 0.7 of the color subcarrier frequency.
It is folded at 5 times the frequency, and the high frequency components of the video signal are superimposed and transmitted in the direction of lower frequencies as a folded signal by sub-sampling, and the frequency is 3.58 MHzwL.
Since the transmitted color signal is converted to approximately 1.8 MHz and transmitted, it is transmitted as a composite signal as an integrated signal, so there is no resolution deterioration due to separation or combination of Y and C, and it is compatible with the television system. This means that full-band transmission is being carried out.

The detailed explanation has been given above using the case of the NTSC television signal as an example, but the same applies to the case of the PAL system. The only difference is that the color subcarrier frequency is 4°43MHz, and the NT
Since it is about 850 kHz higher than SC, about 3.3 MHz is required as the luminance signal passband of the VTR. P
In the AL signal, the color subcarrier is offset by 1/4 cycle, and there is also an offset in the frame direction.Since the phase differs by 180 degrees for each IH in the NTSC system, Is/2 is 4H1 when viewed from the horizontal synchronization standard. '? While the same thing is repeated in the 8H period and the 8 frame period, only the phase changes in the combination of the 8H period and the 8 frame period, and the operation of the present invention is exactly the same.

In the above embodiments, the case where the color burst included in the color television signal itself is used to control the sampling phase and the subsampling phase has been described, but the present invention is not limited to this, and the sampling phase can be controlled as desired. It is also easily possible to configure it by adding signals.

For example, the brightness signal band and the TV signal band to be recorded are
If you cannot choose based on the color subcarrier frequency as in the example, but instead choose a different sampling/subsampling frequency, it is possible to add a new burst signal different from the original color burst signal, or from another point of view. However, depending on the group delay characteristics of the transmission path, rather than gating the sine wave and concentrating energy around the frequency of the sine wave, a squared sine wave pulse or even a square sine wave pulse may be used in order to obtain a wider spectrum spread. A single pulse can also be used.

In short, it is important to match the sampling phase of the pre-processing and the sampling phase of the post-processing, and in the present invention, the key point is to obtain sampling phase control information (PLL phase information) from the result of subsampling.

Next, convert the 1125-line TV signal to VH3-VTR.
If you use an 8-channel sub-sampling circuit, you will get a band that is 8 times the VH3-VTR band, that is, a band of about 2.6M) Iz x 8 = 21 Mllz. This level is sufficient. However, the difference in horizontal frequency is that the two scanning lines of a high-definition television correspond to 525 lines and one scanning line of a product, and the signal waveform also corresponds to 525 lines.
It is better to change it to a 5-way product waveform and record it. As a result,
The full number of effective scan lines of a high-definition television is not recorded, and the top and bottom of the screen are slightly cut off, but this is sufficient for practical purposes.

In addition, in the embodiment, the case of frame sequential is explained, but if it is a repeating element with a constant period, it is not limited to frames, but there are also methods using line sequential using line scanning period and field sequential using field period. Needless to say, there is a possibility (as long as the periodicity of the television system is acceptable).

Furthermore, although the embodiments of the present invention have been explained using VTR recording as an example,
As you can easily understand from the explanation, in addition to "rVTR recording", there are also "disk recording", wired, wireless, satellite, etc.
Needless to say, it is also effective in so-called "communication transmission".

〔effect〕

As described above in detail based on the examples, the present invention has the following features:
For television applications, where definition is more important than smoothness of motion, simple signal processing is performed on commercially available small, inexpensive VTRs using digital frame memory, which is now widely used in home video equipment. In addition to being capable of high-definition recording, it also provides a technology for transmitting television signals with a wider signal band over a relatively narrow band transmission line, and is an ideal solution for application fields that have been unsatisfactory in the past. , it provides a solution to the problem at an extremely low cost, and the scope of application of the present invention is extremely wide.

[Brief explanation of drawings]

Figure 1 is a block diagram of the pre-signal processing system of the present invention, Figure 2 is a block diagram of the post-signal processing system of the present invention, Figure 3 is a diagram explaining signal sampling of the present invention, and Figure 4 is a diagram explaining subsampling. , Fig. 5 is an explanatory diagram of the VTR response and sampling frequency selection when the present invention is applied to a VTR, Fig. 6 is an explanatory diagram of samples/subsamples of a color burst signal, and Fig. 7 is an explanatory diagram of sampling pulse phase control. It is an explanatory diagram. DESCRIPTION OF SYMBOLS 1... Sampling circuit, 2... A, B switch, 3... Frame memory, 4... A, B switch, 5... ID addition circuit, 6... Synchronization separation circuit, 7.・Variable frequency oscillator (6X f 5cVco)
, 8... First frequency divider by 2 circuit, 9... Second frequency divider by 2 circuit, 10... Frequency divider by 3 circuit, 11... Gate circuit, 12... #0 circuit, 13 ...#1 circuit, 14...#2 circuit, 15...arithmetic mean circuit, 1G-subtraction circuit, 17...switching, ID signal generation circuit, 18...sampling circuit, 19 ... Frame memory, 20 ... A, B switch, 21 ... Frame repeat circuit, 22 ... ID detection circuit, 23 ... A, B discrimination circuit.

Claims (1)

[Claims] 1. A television signal transmission system that transmits a television signal through a transmission path with a transmission band narrower than the required transmission band determined by the television system, which is characterized by comprising the following means: . (1) Source sampling means for sampling the television signal to be transmitted at a frequency twice or more than its upper limit frequency. (2) Subsampling means for subsampling each of the plurality of consecutive samples of the output sample string of the source sampling means into a plurality of parts, and dividing it into signals of a plurality of channels. (3) Means for rearranging the plurality of outputs of the sub-sampling means on the time axis and transmitting them channel by channel in a time-division manner every scanning period of a television scanning system. (4) Means for controlling the phase of the source sampling by obtaining PLL phase information from the subsampled results.