JPH05328407A - Device for forming television signal - Google Patents

Abstract

PURPOSE:To prevent invasion of loopback distortion in an auxiliary signal HH by applying amplitude-modulation to a luminance high frequency component of a composite color composite signal, extracting a lower side band so as to generate the auxiliary signal HH shifted to a lower band CONSTITUTION:A television signal VI in which a main part area is superimposed on a composite color composite signal and an auxiliary signal HH is superimposed on upper and lower bar area is sampled by a frequency four times that of, e.g. a chrominance subcarrier at an A/D converter section 1 and the result is converted into a digital signal VID. A separator section 2 applies movement adaptive three-dimension luminance/chrominance signal separation processing and superimposition of the auxiliary signal onto the color composite signal to eliminate crosstalk caused among a luminance signal, chrominance signal and the auxiliary signal thereby forming the color composite signal CV and a high frequency luminance signal HY. A frequency shift section 3 implements carrier suppression amplitude modulation processing by a subcarrier and generates the auxiliary signal HH in which the luminance signal high frequency component is frequency-shifted to a low band.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal composing apparatus, and more particularly, it is suitable for constructing an EDTV system television signal which is compatible with the current television system and has a wide screen. Concerning component devices.

[0002]

2. Description of the Related Art Current television systems (eg NTSC)
The EDTV system is being developed, which can provide a more realistic image service by improving the image quality and definition of TV images and widening the screen while maintaining compatibility with the system).

In this EDTV system, an image having a horizontally long aspect ratio (for example, 16: 9), which has an aspect ratio different from that of the current television system, is provided in the upper and lower portions of the screen with a non-image area (hereinafter abbreviated as upper and lower bar portions). Send an image. The upper and lower bars have auxiliary signals VH for improving vertical resolution,
Auxiliary signals HH for improving the horizontal resolution are respectively superposed on the horizontally long image portion (hereinafter abbreviated as the main portion) to realize high definition and high image quality.

On the other hand, for operation in a studio station such as a broadcasting station, it is desirable that the EDTV system is similar to the current television system, but the auxiliary signal may be damaged by signal processing in studio equipment such as program production. is there.
In addition, the transmission band is secured within the station up to a high band (about 6 MHz). Therefore, in the camera output, the main section has a signal band of 6 MHz, a composite color composite signal similar to the current NTSC television system, and the upper and lower bars have a television signal (hereinafter referred to as V
(Abbreviated as I) and operates in the studio station with this television signal VI, and at the final stage, the auxiliary signal HH is extracted from the composite color composite signal of the main section and superimposed on the main section, and the EDTV system television signal is obtained. Is also considered. Regarding this point, JP-A-1-23549
It is described in No. 4.

[0005]

The extraction of the auxiliary signal HH from the composite color signal described above is performed by subjecting the luminance high frequency component to carrier suppression amplitude modulation with the subcarrier μ ₀ and extracting the lower sideband component thereof. To be done. However, it has been found that a folding phenomenon occurs from a high frequency sampling point due to sampling, and folding distortion is mixed into the auxiliary signal.

Therefore, a first object of the present invention is to generate an auxiliary signal HH for improving the horizontal resolution of a television signal and multiplex it to the main part of a composite color composite signal.
An object of the present invention is to provide a television signal component device in which a folding distortion is not mixed in the auxiliary signal HH in the EDTV type television signal component device.

Still another object of the present invention is to provide an EDTV type television signal constituent device capable of ideally separating a luminance signal and a chrominance signal regardless of the presence or absence of image movement. ..

[0008]

A feature of the present invention is that an auxiliary signal HH is obtained by amplitude-modulating a luminance high-frequency component of a composite color composite signal, extracting a lower sideband thereof, and shifting it to a lower side.
The point is that the complex signal modulation processing by the complex filter is adopted in the part for generating.

Another feature of the present invention is that the three-dimensional luminance / color signal separation processing by the motion adaptive signal processing is adopted for the composite color composite signal of the main portion, and the luminance signal high frequency component is provided with high accuracy. (4.2 to 6 MHz) is separated and extracted.

[0010]

According to the configuration in which the signal processing of the complex amplitude modulation by the complex filter is adopted when the auxiliary signal HH is generated,
The aliasing components from the harmonic sampling points due to the sampling are canceled out, and the auxiliary signal HH having no aliasing distortion can be generated.

Further, according to the configuration in which the three-dimensional luminance / color signal separation processing by the motion adaptive signal processing is adopted for the composite color composite signal of the main part, the luminance signal and the color signal are formed in an almost ideal form. It becomes possible to separate with. Therefore, it is possible to almost faithfully separate and extract the luminance high frequency components (4.2 MHz or more) necessary for improving the horizontal resolution.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the block diagram shown in FIG. The television signal VI in which the main area is a composite color composite signal and the auxiliary signal VH is superimposed on the upper and lower bar areas is sampled by the A / D converter 1 at a frequency four times as high as the color subcarrier fsc. Convert to digital signal VID.

The separation unit 2 performs motion adaptive type three-dimensional luminance / color signal separation processing on the composite color composite signal,
By processing the crosstalk component generated between the luminance, chrominance signal and auxiliary signal by superimposing the auxiliary signal, the signal band 4.2
A composite color composite signal CV of MHz and a high frequency luminance signal HY are created.

In the frequency shifter 3, the subcarrier μ ₀ (16
The carrier suppression amplitude modulation processing by fsc / 7) is performed, and the luminance signal high frequency component (4.2 to 6 MHz) is set to 2.2 to 4 MHz.
The auxiliary signal HH frequency-shifted to the band is generated.

In the process section 5, the signal VD whose time delay is adjusted by the delay circuit 4 is used as the signal in the upper and lower bar area, and the signal CV
The signal of the main area is formed by adding the auxiliary signal HH to the signal of the main section, and a predetermined signal such as a synchronizing signal, μ ₀ phase information and an identification signal is added to form a signal VSD. And D / A
The conversion unit 6 converts the analog signal into an EDTV television signal VS in a form in which the vertical auxiliary signal VH is superimposed on the upper and lower bar regions and the horizontal auxiliary signal HH is superimposed on the main region.

The control signal generator 58 generates clocks and control signals necessary for these signal processings.

FIG. 2 shows the pattern of the signal spectrum of the composite color composite signal in the main area. The same figure (a)
Is an input signal VI, which is a composite color composite signal in which a chrominance signal C orthogonally modulated by a chrominance subcarrier fsc is superimposed on a luminance signal Y having a signal band of 6 MHz. On the other hand, the output signal is shown in FIG. Luminance signal high frequency component YH (4.2 to 6 MH
z) is frequency-shifted and superimposed as an auxiliary signal HH.
In the region of the time frequency f and the vertical frequency ν, the color signal C is the second and fourth quadrants, and the auxiliary signal HH is the conjugate of the Hukinuki H.
The spectra are arranged in the first and third quadrants called ole.

Each block of this embodiment will be described below. FIG. 3 shows an embodiment of the separation unit 2, which is a motion adaptive type 3
It is suitable for extracting the high-frequency luminance signal HY by the dimensional luminance / color signal separation processing.

The LPF circuit 7 extracts a component of the signal VID below 2 MHz as the signal S1. Then, the subtraction circuit 9 subtracts the signal S1 from the signal whose time delay is adjusted by the delay circuit 8 to generate a signal S2 having a component of 2 MHz or more. The motion adaptive YC separation unit 11 performs a motion adaptive luminance / color signal separation process according to the motion information k detected by the motion detection unit 12, and extracts a color signal component C. Then, the subtraction circuit 9 subtracts the color signal component C from the signal delayed by the delay circuit 10 to extract the luminance signal component. The spatiotemporal filter 13 removes a crosstalk component when the auxiliary signal HH is superimposed, and its output is generated as a high-frequency luminance signal HY. Further, in the BPF circuit 14, 2 to 4.2 MH
The z component is extracted as the mid-luminance component YM. Then, the adder circuit 17 adds the color signal component whose time delay is adjusted by the delay circuits 15 and 16, the low luminance component YL and the middle luminance component YM to generate a composite color composite signal CV having a signal band of 4.2 MHz. To do. The motion detector 12
Then, the weighting coefficient WT necessary for superimposing the auxiliary signal HH in a motion adaptive manner is also generated.

FIG. 4 is a diagram showing an embodiment of the motion adaptive YC separation unit 11. With respect to the signal S2, the frame comb filter 18 extracts a color signal component CS suitable for a still image by performing calculation between frames. On the other hand, the line comb filter 19 extracts a color signal component CM suitable for a moving image by calculation between lines. In the coefficient weighting circuit 20, the motion information k (0 < k <
1 and k = 0 at rest), 1-k and k coefficients are respectively weighted, and the adder circuit 21 adds both signals to obtain a color signal component C ((1-k) .CS + k.CM. ) Is generated.

FIG. 5 is a diagram showing an embodiment of the motion detector 12. The signal S1 (2 MHz or less) is detected by the 1-frame difference detection unit 22 as a 1-frame difference signal FD1. On the other hand, for the signal S2 (2 MHz or more), the two-frame difference detection unit 23 detects the two-frame difference signal FD2. The quantization circuit 24 carries out absolute value quantization processing, and the MAX selection circuit 25 gives the larger one of the two values to the motion signal MD.
Output as. Then, the smoothing circuit 26 performs a smoothing process (LPF operation) in the horizontal direction or in the horizontal / vertical direction to generate a signal S3. In the motion information setting circuit 27, the weighting coefficient WT of the motion information k and the auxiliary signal HH having the characteristics shown in FIG.
To occur.

FIG. 6 shows an embodiment of the space-time filter 13. As shown in FIG. 9A, it is configured by a combination of a 262 line delay circuit 28, a coefficient weighting circuit 20, and an addition circuit 21, and as shown in FIG. Realize a filter with the characteristic that the band and dotted line are zero.

Next, another embodiment of the separating unit 2 is shown in FIG. This is suitable for luminance / color signal separation between fields.

The LPF circuit 7 extracts a component of the signal VID below 2 MHz as the signal S1. The subtraction circuit 9 subtracts the signal S1 from the signal whose time delay has been adjusted by the delay circuit 8, and extracts the signal S2 having a signal component of 2 MHz or more. The spatiotemporal filter A29, the spatiotemporal filter B30, and the spatiotemporal filter C31 are time / vertical two-dimensional filters each having a characteristic that the hatched portion shown in FIG. Then, the BPF circuit 14 extracts a signal component of 2 to 4.2 MHz and a luminance signal middle frequency component YM. Further, the delay circuits 15 and 32 adjust the time delays to generate the color signal component C and the luminance signal low frequency component YL. Then, the adder circuit 17 adds these signals, and the signal band is 4.2 MHz.
To generate the composite color composite signal CV. Also,
The high-frequency luminance signal HY is obtained from the output of the space-time filter C.

FIG. 8 shows an embodiment of the spatiotemporal filters A, B and C. Both are 262 line delay circuits 2
This can be realized by a combination of the 8,263 line delay circuit 35, the coefficient weighting circuit 20, the adding circuit 33, and the subtracting circuit 34.

Next, an embodiment of the frequency shift section 3 is shown in FIG. In the HPF circuit 37, the high frequency luminance signal HY is 4.
A component of 2 MHz or higher is extracted as a luminance signal high frequency component YH. The multiplication circuit 38 carries out carrier suppression amplitude modulation by the subcarrier μ ₀ , that is, a multiplication operation of YH · cos2πμ ₀ t. Since the signal is a digital signal with a sampling frequency of, for example, 4 fsc, this multiplication operation is t = nT (T
= 1/4 fsc), which can be realized in the form of a table lookup by a ROM, for example. BPF circuit 3
In 9, the signal component in the band of 2.2 to 4 MHz is extracted, the weighting coefficient WT is weighted by the coefficient weighting circuit 20, and the auxiliary signal H is added.
Generate H. In some cases, the auxiliary signal HH can be generated with a fixed value of WT = 1.

In order to arrange the auxiliary signal HH in the Hukinuki Holes in the first and third quadrants of the time / vertical frequency domain (see the second (b)), the phase of the subcarrier μ ₀ is the phase relationship shown in FIG. Need to meet. That is, the phase of μ ₀ is inverted line by line and frame by frame, and the phase of μ ₀ is controlled so that the points of the same phase fall in each field.

Next, FIG. 11 shows another embodiment of the frequency shift section 3. This is suitable for generating the auxiliary signal HH by complex signal processing.

The high-frequency luminance signal HY is input to the complex HPF circuit 40, and the real part YH of the luminance high-frequency component is calculated by complex calculation.
R, the imaginary part component YHI is extracted. Then, the multiplication circuit 38
Then, the multiplication operation of cos 2πμ ₀ t is performed on the real part component and sin 2πμ ₀ t is performed on the imaginary part component. Adder circuit 41
And add both signals, and the BPF circuit 42 adds 2.2 to 4M.
A signal component in the Hz band is extracted, and the weighting coefficient WT is weighted by the coefficient weighting circuit 20 to generate the auxiliary signal HH. Note that the multiplication operation may be performed at t = nT (T = 1/4 fsc),
It can be easily realized in the form of table lookup by ROM. In some cases, the weighting coefficient may be a fixed value of WT = 1 to generate the auxiliary signal HH.

Next, an embodiment of the process unit 5 is shown in FIG.
Shown in. The adder circuit 43 adds the signal CV and the signal HH to produce a composite color composite signal VD 'in which the auxiliary signal HH is superimposed on the main area. Selection circuit 44
Then, according to the mode signal MOD generated by the control circuit 45, the signals VD, VD 'and MSK are selectively output as shown in FIG. For example, in Mode I, the input signal is the current NTS.
In the case of a C television signal, the upper and lower bar area is the signal M.
SK (for example, a specific signal such as black or gray), the main portion area selects the signal VD '. Mode II is EDT
In the case of the V system signal VI, the upper and lower bar regions are the signal V
The signal VD 'is selected for the D and main area. On the other hand, Mode III is a case where both the auxiliary signals VH and HH are superimposed by the EDTV system, and the signal VD is selected in both the upper and lower bar areas and the main section area. In the sync signal adding circuit 46,
Predetermined signals such as synchronization signals, burst signals, and identification signals are added. Further, the μ ₀ information adding circuit 47 adds the phase information (8 fsc / 7 signal) of the sub carrier μ ₀ necessary for reproducing the auxiliary signal HH on the receiving side in the modes I and II. Then, the aperture correction circuit 48 performs aperture correction processing for emphasizing the horizontal high-frequency component, and the auxiliary signal V
An EDTV system television signal in which H and HH are superimposed is generated.

As described above, according to the present embodiment, the wide band (6 MH
z) A composite color composite signal of EDT in which a high frequency component of a luminance signal and an auxiliary signal HH are superimposed on a main area
It is possible to realize a component device that generates a V-system television signal with almost ideal characteristics.

Next, a second embodiment of the present invention will be described with reference to the block configuration shown in FIG. This is the auxiliary signal HH
However, it can be realized with an extremely simple structure, and is suitable as a low-cost simple type.

The signal VI is sampled by the A / D converter 1 at a frequency four times as high as the color subcarrier fsc, for example, and converted into a digital signal VID. In the LPF circuit 49, the component below 4.2 MHz of the composite color composite signal is signal C
Extract as V. Also, in the HPF circuit 50, 4.2M
The components above Hz are extracted as the high-frequency luminance signal HY.
The HPF circuit 50 is preferably composed of horizontal and vertical two-dimensional line-comb filters, but in some cases a horizontal one-dimensional structure is also possible.

In the frequency shifter 3, the subcarrier μ ₀ (16
carrier suppression amplitude modulation processing by fsc / 7),
The auxiliary signal HH frequency-shifted to 2.2 to 4 MHz is generated.

In the process section 5, the signal VD whose time delay is adjusted by the delay circuit 51 is used as the signal in the upper and lower bar area, and the signal C.
A signal of the main part area is formed by a signal obtained by adding the auxiliary signal HH to V, and a predetermined synchronizing signal, an identification signal, μ ₀ phase information and the like are added to form a signal VSD. Then, the D / A conversion unit 6 converts the signal into an analog signal, and a vertical auxiliary signal VH is superimposed on the upper and lower bar portions and a horizontal auxiliary signal HH is superimposed on the main portion area. Generate VS.

The control signal generator 58 generates clocks and control signals necessary for these signal processings.

As described above, according to this embodiment, although the image quality is slightly deteriorated, it is possible to realize a low-cost constituent device with an extremely simple structure.

Next, a third embodiment of the present invention will be described with reference to the block diagram shown in FIG. This is suitable for constructing the auxiliary signal HH in the form of field line pairs.

The signal VI is sampled by the A / D converter 1 at a frequency four times as high as the color subcarrier fsc, for example, and converted into a digital signal VID. The field line pair separation unit 52 produces a composite color composite signal CVP and a high-frequency luminance signal HYP whose signals are generated by the same components in the scanning lines forming a pair in the first and second fields.

In the frequency shifter 3, the subcarrier μ ₀ (16
carrier suppression amplitude modulation processing by fsc / 7),
Auxiliary signal HH frequency-shifted to 2.2-4 MHz band
To generate.

In the process unit 5, the signal VD whose time delay is adjusted by the delay circuit 53 constitutes the upper and lower bar regions, and the signal obtained by adding the auxiliary signal HH to the signal CVP constitutes the main region. Also, a signal VSD is created by adding a predetermined synchronization signal, identification signal, and μ ₀ phase information. Then, the D / A converter 6
The analog signal is converted into an analog signal by E, and the auxiliary signals VH and HH are superposed on the upper and lower bar regions and the main region, respectively.
A television signal VS of the DTV system is generated.

The control signal generator 58 generates clocks and control signals required for these signal processings.

FIG. 16 shows an embodiment of the field line pair separating section 52. The figure (a) shows a structure, (b) shows the formation form of a field line pair. In the present invention, the scan line of the first field and the scan line of the second field separated by 262 lines form a pair. And
The 2-4.2 MHz signal component C & YM of the composite color composite signal and the auxiliary signal HH assign the same component signal to the scanning lines forming these pairs. That is,
Scan line a of the first field, scan line b of the second field
Then, an average value (Sa + Sb) / 2 of the signals Sa and Sb is assigned.

The LPF circuit 7 extracts the component of the signal VID below 2 MHz as the signal S1. The subtraction circuit 9 subtracts the signal S1 from the signal whose time delay has been adjusted by the delay circuit 8 to extract the signal S2 having a signal component of 2 MHz or more.
Then, the signal delayed by 262 lines by the 262 line delay circuit 28 and the signal S2 are averaged by an averaging circuit 54 to generate a signal component S4 to be assigned to the scanning lines of the field line pair. Selection circuit 55
Then, according to the field information, the signal S4 in the first field period and the output signal of the 262 line delay circuit 28 in the second field period are selected and output to generate the signal S5 in the form of a field line pair. And the BPF circuit 1
In 4, the 2 to 4.2 MHz component is extracted as the signal C & YM. The adder circuit 17 adds the signal C & YM to the luminance signal low frequency component YL whose time delay has been adjusted by the delay circuit 57 to generate a composite color composite signal CVP having a signal band of 4.2 MHz. Further, the signal S5 and the signal delayed by one frame period by the one-frame delay circuit 56 make an average value of both signals by the averaging circuit 54 to generate the high-frequency luminance signal HYP.

As described above, according to the present embodiment, it is possible to realize the EDTV type television signal constituent device which superimposes the auxiliary signal HH in the form of a field line pair.

[0046]

According to the present invention, the luminance signal high frequency component of the main area is extracted from the signal composed of the auxiliary signal VH in the upper and lower bar areas and the wide band composite color composite signal in the main area. It is possible to create a television signal constituent device capable of generating an EDTV television signal superimposed on the main area as the auxiliary signal HH with substantially ideal characteristics.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a first embodiment according to the present invention.

FIG. 2 is an explanatory diagram of a signal spectrum.

FIG. 3 is a block configuration diagram of an embodiment of a separation unit.

FIG. 4 is a diagram showing an embodiment of a motion adaptive YC separation unit of the separation unit.

FIG. 5 is a diagram illustrating an example of a motion detection unit of a separation unit.

FIG. 6 is a diagram illustrating an example of a spatiotemporal filter of a separation unit.

FIG. 7 is a block configuration diagram of another embodiment of the separation unit.

FIG. 8 is a diagram showing an example of the spatiotemporal filters A, B, and C of the separation unit.

FIG. 9 is a diagram illustrating an example of a frequency shift unit.

FIG. 10 is a phase relationship diagram of subcarriers in the frequency shift unit.

FIG. 11 is a diagram showing another embodiment of the frequency shift unit.

FIG. 12 is a diagram illustrating an example of a process unit.

FIG. 13 is an explanatory diagram of signal processing in the process unit.

FIG. 14 is a block configuration diagram of a second embodiment of the present invention.

FIG. 15 is a block configuration diagram of a third embodiment of the present invention.

FIG. 16 is a diagram illustrating an example of a field line pair separation unit.

[Description of Reference Signs] 1 ... A / D converter, 2 ... Separator, 3 ... Frequency shifter,
4 ... Delay circuit, 5 ... Process section, 6 ... D / A conversion section, 7
... LPF circuit, 8, 10, 15, 16 ... Delay circuit, 9 ...
Subtraction circuit, 11 ... Motion adaptive YC separation unit, 12 ... Motion detection unit, 13 ... Spatio-temporal filter, 14 ... BPF circuit, 17 ...
Adder circuit, 18 ... Frame comb filter, 19 ... Line comb filter, 20 ... Coefficient weighting circuit, 21 ... Adder circuit,
22 ... 1-frame difference detection unit, 23 ... 2-frame difference detection unit, 24 ... Quantization circuit, 25 ... MAX selection circuit,
26 ... Smoothing circuit, 27 ... Motion information setting circuit, 28 ... 2
62 line delay circuit, 29 ... Spatiotemporal filter A, 30 ...
Space-time filter B, 31 ... Space-time filter C, 32 ... Delay circuit, 33 ... Addition circuit, 34 ... Subtraction circuit, 35 ... 26
3-line delay circuit, 37 ... HPF circuit, 38 ... Multiplication circuit, 39 ... BPF circuit, 40 ... Complex HPF circuit, 41 ... Addition circuit, 42 ... BPF circuit, 43 ... Addition circuit, 44 ... Selection circuit, 45 ... Control circuit , 46 ... Sync signal adding circuit, 4
7 ... μ ₀ information addition circuit, 48 ... Aperture correction circuit, 4
9 ... LPF circuit, 50 ... HPF circuit, 51 ... Delay circuit,
52 ... Field line pair separation unit, 53 ... Delay circuit,
54 ... Averaging circuit, 55 ... Selection circuit, 56 ... 1-frame delay circuit, 57 ... Delay circuit, 58 ... Control signal generation section.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masahiro Kageyama 1-280 Higashi Koikeku, Kokubunji, Tokyo Inside Central Research Laboratory, Hitachi Ltd. (72) Inventor Kazuo Ishikura 1-280 Higashi Koikeku, Kokubunji, Tokyo Hitachi Ltd. Central research institute

Claims (4)

[Claims] 1. An EDTV system television signal constituent device for transmitting an image having a horizontally long aspect ratio different from that of a current television system by providing a non-image area on the upper and lower sides of a screen. Means for extracting a horizontal luminance high-frequency component of a composite color composite signal of an image having a different aspect ratio, and means for generating a high-definition signal obtained by shifting the extracted horizontal luminance high-frequency component to a low frequency band, In the EDTV system television signal formed by superimposing the generated high-definition signal on the composite color composite signal of the image having the aspect ratio, the means for generating the high-definition signal is a complex amplitude modulation of the horizontal luminance high-frequency component. A television signal constituent device, characterized in that a high-definition signal is generated by performing frequency shift to a low frequency band by signal processing. 2. A horizontal luminance high frequency component is extracted from a composite color composite signal of an image having a horizontally long aspect ratio by three-dimensional luminance / color signal separation processing by motion adaptive signal processing. The television signal constituent device according to. 3. A luminance of a frequency band on which a color signal of a composite color composite signal of an image having a horizontally long aspect ratio is superimposed.
The chrominance signal component and the high-definition signal component form a field line pair with one frame as a cycle, and the above-mentioned luminance / color signal and high-definition signal are the same component signal for the scanning lines of the field line pair. The television signal composing apparatus according to claim 1, wherein: 4. The television according to claim 1, wherein a horizontal luminance high-frequency component is extracted by performing inter-field luminance / color signal separation processing on a composite color composite signal of an image having a horizontally long aspect ratio. Signal components.