JP2517652B2 - Band-compressed television signal receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a so-called MUSE (Multiple Sub-nyquist Sa
The present invention relates to a receiver for a band-compressed television signal according to the mpling encoding) system, and particularly to realize a still display function.

[Prior Art] The baseband bandwidth of a high definition television signal is about 30
[MHz], which cannot be transmitted by the current satellite broadcasting channel.
z] is required for band compression.

A so-called MUSE system has been proposed as one of systems for band-compressing and transmitting high-definition television signals.

In this MUSE method, the band compression method as exemplified below is used. (1) The time axis of the color signal is compressed to 1/4, and the luminance signal is multiplexed in the horizontal blanking period.
(2) In a still region of an image, dot interlace by offset sampling between fields and between frames is used. (3) In the moving area of the image, dot interlace by offset between lines is used. (4) Deterioration of resolution during pan and tilt is kept to a minimum by motion compensation.

Therefore, in the receiving apparatus, a band extension configuration corresponding to these band compression methods is required.

[Problems to be Solved by the Invention] Recently, television receivers having a still display function have appeared. Therefore, it is desired that a receiving device that receives a MUSE-type television signal also has a still display function.

However, as described above, since the MUSE-type television signal has a different signal format from the so-called NTSC-type television signal, the existing still display configuration cannot be applied as it is.

The present invention has been made in consideration of the above points,
An object of the present invention is to provide a band-compressed television signal receiving apparatus capable of realizing a still display function with a simple configuration for a band-compressed television signal according to the MUSE system.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, the luminance signal and the color signal are respectively subjected to dot interlacing by inter-field and inter-frame offset sampling in a still region, In the moving area, a band-compressed television signal subjected to dot interlacing due to an offset between lines is received and demodulated, and after the interpolating means that restores the dot interlacing for the luminance signal to the original area for the stationary area. It is equipped with a temporal filter that reduces unnecessary components on the time axis when switching between the interpolation process and the interpolation process for the moving area, and the line-sequential color signal is provided next to the interpolating means for restoring the dot interlace for the color signal. Of a band-compressed television signal provided with a line-sequential decoding circuit for converting a color difference signal for each scanning line In the receiving device, when the still image display mode is selected, the frame brightness signal of the frame is stored in the frame memory 1 in the temporal filter circuit, and the stored brightness signal is constantly output to the next stage circuit of the temporal filter circuit. In the case of the luminance signal holding means to be operated and the operation mode other than the still image display mode, the color signal from the interpolation means for the color signal is given to the line sequential decoding means as it is, and the still image display mode is selected. In this case, a built-in frame memory is provided with a color signal holding means for storing one frame of color signal and constantly outputting the stored color signal.

[Operation] When the still image display mode is entered, the luminance signal holding means stores one frame of the luminance signal in the frame memory in the temporal filter circuit, and the stored luminance signal is maintained while the still image display mode is selected. Is repeatedly output. On the other hand, when the still image display mode is entered, the color signal holding means stores the color signal of one frame in the built-in frame memory, and repeatedly outputs the stored color signal while the still image display mode is selected. Let

Thus, the same luminance signal and chrominance signal are repeatedly output to display the stillness.

In the modes other than the still image display mode, the luminance signal holding means does not perform processing, and the temporal filter circuit uses the frame memory to reduce unnecessary components at the boundary between the still area and the moving area, and the color signal holding means does not. , The input color signal is output as it is to the next stage circuit. That is, these holding means do not affect the normal operation.

Embodiment An embodiment of the present invention will be described in detail below with reference to the drawings.

Overall Configuration of Receiving Device FIG. 1 shows the overall configuration of the receiving device according to this embodiment. It is captured by a parabona antenna (not shown) and is transmitted by a satellite broadcasting (BS) tuner (not shown) to about 8 units.
A television signal according to the MUSE system demodulated to the base band of [MHz] is input to this receiving device.

The input television signal is applied to the analog / digital conversion circuit 1, converted into digital data by the analog / digital conversion circuit 1, and then applied to the de-emphasis circuit 2. The de-emphasis circuit 2 is
The de-emphasized signal is subjected to the reverse processing of the processing by the emphasis circuit of the transmission system, and the motion detection circuit 3,
It is given to the inter-frame interpolation circuit 4 and the sync separation / timing generation circuit 5.

The motion detection circuit 3 detects the motion of the television signal after the de-emphasis process and outputs the motion detection signal to each circuit described later.

The sync separation / timing generation circuit 5 separates the sync signal from the television signal after the de-emphasis process, and forms and outputs a control signal for controlling the operation timing of each circuit described later.

The inter-frame interpolation circuit 4 uses the frame memory 6 because the stationary area of the received television signal is dot-interlaced by inter-frame offset sampling.
The data before one frame is interpolated as data for a dot that has been compressed by using.

At this time, the data one frame before is moved in a predetermined direction based on the motion detection signal supplied from the motion detection circuit 3 and is interpolated so as to prevent deterioration of the resolution of the panned / tilted screen. In addition, noise reduction processing is performed using the frame memory 6.

The television signal output from the inter-frame interpolation circuit 4 is applied to the low-pass filter circuit 7, the band is limited, the sampling frequency is converted by the sampling frequency conversion circuit 8, and the next inter-field interpolation circuit It is given to the inter-field interpolation circuit 9 so as to facilitate the processing by 9.

The inter-field interpolation circuit 9 interpolates the static area using dot interlacing by inter-field offset sampling, so that the field memory 10 is used to interpolate using data from one field before as data for a dot having no data. . At this time, the data position is corrected in the horizontal direction according to the motion detection signal supplied from the motion detection circuit 3, and the panned screen is treated as a still region to prevent deterioration of resolution. The television signal interpolated between the fields is supplied to the adaptive mixing circuit 11.

The television signal inter-frame interpolated by the inter-frame interpolating circuit 4 described above is given to the field interpolating circuit 13 via the sub-sample switch circuit 12. The sub-sample switch circuit 12 opens at the data timing of the dot interpolated between frames and replaces the dot data with "0", and closes the dot data with the original frame data and closes that data. To pass through. The field interpolation circuit 13 has a memory for several lines, and stores the data of the dot of interest (dot to be processed)
It is formed by interpolating from data of several dots that are adjacent in the vertical and horizontal directions.

This is because the moving area of the image is dot-interlaced by the inter-line offset and cannot be cubically interpolated.

The television signal interpolated in the field in this manner is given to the noise coring 14. The noise coring 14 removes a component whose frequency is equal to or higher than a predetermined frequency and whose level is equal to or lower than a predetermined value as a noise component, and supplies the television signal after the noise removal to the adaptive mixing circuit 11 described above.

The motion detection circuit 3 supplies a motion detection signal to the adaptive mixing circuit 11. The adaptive mixing circuit 11 interpolates a television signal interpolated as a static area given by the inter-field interpolating circuit 9 and a moving area given by the noise coring 14 with a ratio according to the motion detection signal. The mixed television signal is mixed and the mixed television signal is supplied to the low-frequency replacement circuit 15.

The low-frequency replacement circuit 15 is supplied with the television signal from the de-emphasis circuit 2. The low-pass replacement circuit 15
4 of the television signal given from the adaptive mixing circuit 11
The component below [MHz] is replaced with the component below 4 [MHz] of the television signal supplied from the de-emphasis circuit 2, and the replaced television signal is supplied to the temporal filter circuit 16.

Here, the low-frequency replacement circuit 15 is provided for the luminance signal 4
In the region below [MHz], there is no aliasing due to inter-frame offset suppression, so the frequency characteristics in the vertical direction are made flat by replacement, and the vertical direction provided in the interpolation circuits 9 and 13 described above. This is to simplify the configuration of the filter.

The temporal filter circuit 16 has the detailed configuration shown in FIG. 2, and basically uses the frame memory 17 to perform processing so as to reduce the change in resolution at the change point between the still area and the moving area. Further, in the case of this embodiment, in addition to such basic processing, processing for realizing a still display function as described later is performed. The television signal from the temporal filter circuit 16 is given to the matrix circuit 18.

In the case of a television signal according to the MUSE system, since the color signal is inserted in the horizontal blanking period, when the display processing is performed by a cathode ray tube (CRT) display device (not shown), the signal in the horizontal blanking period is meaningless. Therefore, even if the television signal from the temporal filter circuit 16 to the matrix circuit 18 includes a color signal, that portion is meaningless, and from this point, the processing system from the low-pal filter circuit 7 to the frame memory 17 is a luminance signal. Constitutes the processing system of.

The television signal output from the inter-frame interpolation circuit 4 described above is applied to the time axis expansion circuit 20. The time axis expansion circuit 20 extracts the color signal compressed and inserted into 1/4 in the horizontal blanking period based on the control signal supplied from the sync separation / timing generation circuit 5,
The color signal is expanded four times on the time axis and supplied to the inter-field interpolation circuit 21.

The inter-field interpolation circuit 21 uses the field memory 22 to interpolate a dot having no data in the data one field before so as to correspond to the dot interlace with respect to the static area. Also in this case, similarly to the processing system of the luminance signal, since one image is formed by the data between four fields by the inter-frame interpolation and the inter-field interpolation, the resolution is increased. Become. The color signal interpolated between the fields is supplied to the adaptive mixing circuit 23.

The television signal that has passed through the noise core ring 14 described above is applied to the time axis expansion circuit 24. This time axis expansion circuit extracts a color signal which is inserted by compressing the time axis to 1/4 in the horizontal blanking period based on the control signal supplied from the sync separation / timing generation circuit 5, and extracts the color signal of the color signal. The time axis is expanded four times and supplied to the field interpolation circuit 25.

The field interpolating circuit 25 is provided corresponding to the dot interlacing due to the line-to-line offset of the color signal for the moving area, and is used in the vertical and horizontal directions by using a built-in memory for several lines. Data of a dot of interest is interpolated from adjacent dot data, and the interpolated color signal is given to the adaptive mixing circuit 26.

The adaptive mixing circuit 26 is provided with a motion detecting circuit from the motion detecting circuit 3, and the adaptive mixing circuit 26 inter-field interpolates the inter-field interpolating circuit 21 in consideration of the static area.
And the color signal from the in-field internal performance circuit 25, which is interpolated in the field in consideration of the moving area, are mixed at a ratio determined according to the motion detection signal. Output to.

Unlike the conventional circuit, the stationary display frame memory unit 26 is provided in this embodiment and will be described in detail in the third section.
As shown in the figure, when the static display mode is not selected, the color signals supplied from the adaptive mixing circuit 23 are sequentially passed, and when the static display mode is selected, each frame The same color signal is output.

The color signal from the still display frame memory unit 26 is given to the line-sequential decoding circuit 27. Color difference signals R-Y and B-Y are line-sequentially inserted in the color signal according to the MUSE system, and the line-sequential decoding circuit 27 separates and extracts these color difference signals and gives them to the sampling frequency conversion circuit 28. The sampling frequency conversion circuit 28 receives the chrominance signal having the same sampling frequency as the sampling frequency of the luminance signal given from the temporal filter circuit 16 to the matrix circuit 18 so that the conversion processing by the matrix circuit 18 can be favorably performed. Convert the sampling frequency of.

The matrix circuit 18 performs a matrix process on the luminance signal supplied from the temporal filter circuit 16 and the color difference signal supplied from the sampling frequency conversion circuit 28 to convert it into three primary color signals, and converts each primary color signal into corresponding digital / analog conversion. Apply to circuits 29R, 29G, and 29B. Each of the digital / analog conversion circuits 29R to 29B converts the primary color signal, which is a digital signal, into an analog signal and outputs it to a display device (not shown).

Temporal Filter Circuit 16 Next, the detailed configuration of the temporal filter circuit 16 will be described with reference to FIG.

In FIG. 2, the luminance signal low-pass-replaced by the low-pass replacement circuit 15 is given to the two-dimensional low-pass filter circuit 30, is two-dimensionally waved, and is given to the subtraction circuit 31 as a subtraction input. The subtraction circuit 31 is supplied with the luminance signal from the low-frequency substitution circuit 15 as a subtracted input, and the high-frequency component of the luminance signal for the temporal filter circuit 16 is extracted by the subtraction processing. By the way, the high frequency component thus obtained contains a large amount of normal noise components and high frequency components generated at the boundary between the static region and the dynamic region because the processing is different between the static region and the dynamic region. I'm out. Therefore, these are removed using past information.

The high frequency component of the luminance signal is given to the subtraction circuit 32 as a subtracted input, and the subtraction circuit 32 subtracts the delay signal including the past history given from the frame memory 17 from the high frequency component of the luminance signal. Then, the subtraction signal is given to the conversion table circuit 33 and the subtraction circuit 34. Conversion table circuit 33
Obtains a level output signal corresponding to the input signal level and supplies it to the subtraction circuit 34. The subtraction circuit 34 subtracts the converted signal from the signal from the subtraction circuit 32. Here, in the conversion of the conversion table circuit 33, the output signal via the subtraction circuit 34 is a signal component from the subtraction circuit which is given to the subtraction circuit 34,
The conversion is performed so that a component having a predetermined frequency or higher and a predetermined level is suppressed to a predetermined level or lower. The output signal from the subtraction circuit 34 is given to the frame memory 17 via a selector circuit 35, which will be described later, and delayed by one frame via the frame memory 17, and then the subtraction circuit 32 described above is passed through the coefficient unit 36. Given to.

In this way, the cyclic processing is performed to suppress unnecessary high frequency components at the boundary between the moving region and the stationary region, and the subtraction circuit
The processed high frequency component from 34 is supplied to the absolute value minimum selection circuit 37 as a first selection input. Here, a general noise component may also be mixed, and the one through the subtraction circuit 34 is not necessarily the one that is optimally filtered, and the high-frequency component before through the subtraction circuit 34 is also included. It is given as a second selection input to the absolute value minimum selection circuit 37, the average value of the high frequency components before and after passing through the subtraction circuit 37 is obtained by the average value circuit 38, and given to the absolute value minimum selection circuit 37 as a third selection input. I am trying.

The absolute minimum selection circuit 37 selects the smallest one from the selection inputs and supplies it to the addition circuit 39. The adder circuit 39 has 2
The low-frequency component of the luminance signal is given from the three-dimensional low-pass filter circuit 30, and the processed high-frequency component is added back to the luminance signal of a predetermined band, and output to the matrix circuit 19 via the selector circuit 40 described later. .

In addition to the configuration for realizing the original function of the temporal filter circuit 16 as described above, in this embodiment, the configuration for realizing the still image display function is the temporal filter circuit.
It is provided in 16.

The selector circuit 35 described above has a three-input configuration,
The input terminal is switched according to the control signal given from the sync separation / timing generation circuit 5. In the modes other than the still image display mode, the subtraction output from the subtraction circuit 34 is input.

On the other hand, in the still image display mode, the selector circuit 35 operates the low-frequency replacement circuit 15 only during the first one frame.
The luminance signal from is selected and stored in the frame memory 17 in the subsequent stage of the selector circuit 35, and during the subsequent still image display mode, the output signal from the frame memory 17 is selected and given to the frame memory 17. Switch operation.
That is, in the still image display mode, a luminance signal for one frame is fetched, and thereafter, the luminance signal is circulated and stored in the frame memory 17, and the same luminance signal is output from the frame memory 17 for each frame. ing.

The luminance signal output from the frame memory 17 is given to the selector circuit 40 described above. This selector circuit 40
Switches the input terminal according to the control signal provided from the sync separation / timing generation circuit 5. As described above, the luminance signal from the adding circuit 39 is selected in the modes other than the still image display mode, and the luminance signal from the frame memory 17 is selected in the still image display mode.

Thus, in the still image display mode, the luminance signal once stored in the frame memory 17 is the selector circuit 40.
Are supplied to the matrix circuit 18 together with each frame via.

Still Display Frame Memory Unit 26 Next, the details of the still display frame memory unit 26 will be described with reference to FIG.

The color signal output from the adaptive mixing circuit 23 is given to the selector circuit 45. The selector circuit 45 switches the input terminal according to the control signal supplied from the sync separation / timing generation circuit 5. The color signal from the adaptive mixing circuit 23 is selected in the modes other than the still image display mode, and the color signal from the frame memory 46 provided in the next stage of the selector circuit 45 is selected in the still image display mode.

The color signal output from the frame memory 46 is fed back to the selector circuit 45 and is also given to the output selector circuit 47. The color signal from the input selector circuit 45 is also directly applied to the selector circuit 47. The selector circuit 47 switches the input terminal according to the control signal given from the sync separation / timing generation circuit 5. In the modes other than the still image display mode, the color signal from the selector circuit 45 is selected and output to the line sequential decoding circuit 27. In the still image display mode, the color signal from the frame memory 46 is selected and the line sequential decoding circuit 27 is selected. Output to.

Here, in the still image display mode, since the color signal output from the frame memory 46 is selected by the selector circuit 45 and stored in the frame memory 46, the color signal output via the output selector circuit 47 is Each frame is the same, so that a still image can be displayed.

Therefore, according to the above-described embodiment, the still image display function can be realized even in the band compression television signal receiving apparatus according to the MUSE system. As a result, the frame memory 17 in the temporal filter circuit 16 is used, so that the added component parts can be simpler and smaller than the addition of the function. Further, for the color signals, the still image frame memory is inserted not in the color difference signal processing portion but in the color signal processing portion, so that only one frame memory is required to realize the still image display function. From the point of view, it also keeps the structure from becoming complicated.

In the above-described embodiment, in the still image display mode, the signals output from the frame memories 17 and 46 are returned to the frame memories 17 and 46 in order to repeatedly output the same signal from the frame memories 17 and 46. However, the writing to the frame memories 17 and 46 may be stopped and the reading may be repeated. In this case, depending on the semiconductor element used for the frame memories 17 and 46, writing is stopped and only reading is repeated, so that a lot of noise may be mixed in the output signal with the lapse of time.

[Effects of the Invention] As described above, according to the present invention, a still image display function can be realized in a receiving device for a band-compressed television signal by adding a slight and simple configuration.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a band-compressed television signal receiving apparatus according to the present invention, FIG. 2 is a block diagram showing a detailed configuration of a temporal filter circuit thereof, and FIG. 3 is a still image frame memory thereof. It is a block diagram which shows the detailed structure of a part. 16 ... Temporal filter circuit, 17, 46 ... Frame memory, 26 ... Still image frame memory section, 35, 40, 45,
47 …… Selector circuit.

 ─────────────────────────────────────────────────── ─── Continuation of front page Examiner Akira Suzuki (56) References JP-A-2-13190 (JP, A) JP-A-1-286688 (JP, A) JP-A-62-51390 (JP, A) Special Features Kai 61-248691 (JP, A)

Claims (1)

(57) [Claims] 1. A luminance signal and a chrominance signal are dot interlaced by inter-field and inter-frame offset sampling in a static region, and dot interlaced by an inter-line offset in a moving region. A band-compressed television signal is received and demodulated, and a time axis generated at the time of switching between interpolation processing for a stationary area and interpolation processing for a moving area after the interpolation means for restoring dot interlacing for a luminance signal. A temporal filter that reduces the above unnecessary components is provided, and a line-sequential decoding circuit that converts a line-sequential color signal into a color-difference signal for each scanning line is provided at the next stage of the interpolating unit that restores dot interlacing to the color signal. When the still image display mode is selected in the band compression television signal receiving device, Luminance signal holding means for storing one frame of luminance signal in the frame memory of the temporal filter circuit and repeatedly outputting the stored luminance signal to the next stage circuit of the temporal filter circuit, and an operation mode other than the still image display mode. In the case of, the color signal from the interpolating means for the color signal is given to the line-sequential decoding means as it is, and when the still image display mode is selected, the color signal of one frame is stored in the built-in frame memory. A band-compressed television signal receiving device, comprising: a color signal holding unit that stores the color signal and repeatedly outputs the stored color signal to the line-sequential decoding unit.