FR2881601A1 - Composite video signal synchronization device for e.g. national television standards committee television system, has signal extremum detection unit detecting position of extremum of received composite video signal - Google Patents

Abstract

The device has a signal extremum detection unit (4) detecting the position of an extremum of a received composite video signal. The unit (4) detects a frame start position corresponding to the received video signal from the position of the detected extremum. The unit (4) delivers a frame start position signal, in an output, where the position signal indicates the determined frame start position. An independent claim is also included for a composite video signal receiver comprising a composite video signal synchronization regeneration device including a vertical synchronization device.

Description

1 2881601 DEVICE FOR SYNCHRONIZING COMPOSITE VIDEO SIGNALS

DESCRIPTION

TECHNICAL AREA

  The present invention relates to a device for vertically synchronizing a composite video signal, a device for regenerating horizontal and vertical synchronization of a composite video signal, as well as to a composite video signal receiver.

  The composite video signals concerned are interlaced-frame analog video signals such as, for example, those used in NTSC television systems (National Television Standards Commitee) or PAL / SECAM (for Phase Alternating Line / Sequential Color with Memory). ).

  STATE OF THE PRIOR ART The extraction of the synchronization signal from a composite video signal is necessary in any television receiver. The horizontal and vertical synchronization signals must be extracted from the video data stream so as to be able to synchronize between the image displayed on the screen of a receiver and the corresponding input signal: the horizontal synchronization signal indicates to the screen monitor when you need to start a screen scan from the left and the vertical sync signal indicates when to start scanning from the top of the screen.

  2881601 2 genlock (or generator-lock type) systems, used for embedding text or graphic data in a standard television format, also need the extraction of synchronization signals in order to ability to combine the data to be overlaid and the video signal for simultaneous display.

  Each composite video image is formed of two interleaved frames, one corresponding to odd screen scan lines and the other corresponding to even screen scan lines, the resulting video image on the screen being formed by interlaced scanning. For example, the PAL / SECAM system can transmit 50 interlaced frames per second, or 25 frames per second, with an image coding on 625 lines; NTSC uses 60 interlaced frames per second, or 30 frames per second, with 525-line image coding.

  The coding of the vertical or horizontal synchronization pulses on a sequence of a composite video signal depends of course on the system used. This coding is described in the following document: Conventional Television Systems, Recommendation ITU-R BT.470-6, Nov. 1998. For each transmission standard there is a typical vertical synchronization signal and a horizontal synchronization signal given. A synchronization signal characteristic of a standard, which is not noise or echo, is called a normalized synchronization signal.

  In particular, a vertical synchronization operation is intended to detect the coding sequence of the vertical synchronization pulses in the received composite video signal. There is then a shift of half a line from the beginning of the line positions between the vertical sync pulses of the odd and even fields. This property is also used to detect the parity of a frame and to determine the numbers of the scan lines in an Image.

  This offset is not specific to NTSC type systems and the same property exists in PAL or SECAM type systems. Thus, a similar vertical synchronization process can be used for any television system based on analogue signal reception in the world.

  In a conventional synchronization block of a television receiver (see for example Standard Handbook of Video and Television Engineering, Whitakaker JC, Benson KB, McGraw-Hill, Third edition, 2000, pages 17-47), vertical deflection signals and horizontal are generated in parallel, along two separate branches, from the common output signal of the synchronization extractor: a first branch, for the vertical deflection, comprises a vertical integrator input of a vertical oscillator which is itself even followed by a vertical deflection signal amplifier; a second branch, for horizontal deflection, comprises a horizontal phase detector at the input of a horizontal oscillator which is itself followed by a horizontal deflection signal amplifier.

  A disadvantage of this conventional sync block is that it has low noise immunity and low image stability.

  Such a conventional synchronization device, even if it includes recent developments (see for example A new multistandard video processor including deflection drive circuits which is controlled by digital process, Baba Y., Yamazaki N., Sengoku Y., Nishiyama S. , Shimuzu H., IEEE Transactions on Consumer Electronics, vol.35, issue 3, Aug.1989, pages 308-314), uses a synchronization extractor (Sync Separator) and implements the rising edge synchronization method (or downstream) of the sync pulse of a composite video signal (see the article New method for the implementation of an NTSC digital video decoder, Kuo Ku & YT Chen, IEEE Transactions on Consumer Electronics, vol.48, N 2, May 2002). In this conventional device, a threshold level of the signal (or slicing level) is established at a certain height below the peak of the synchronization signal (see article IC Signal-Processing Circuit for TV Receivers, Cense W., Rongen J IEHE Journal of Solid-State Circuits, SC-4, No. 4, Aug. 1969, pages 202-210). The output of the synchronization extractor reaches its maximum value if the input signal is above the threshold level and reaches its minimum value if the input signal is below the threshold level.

  With the devices implementing such a conventional synchronization method, if the threshold level is too high, problems arise, which are due to noise or multipath echoes, on the vertices of the vertical synchronization pulses; and if the threshold level is too low, the same problems appear at the base of the vertical sync pulses.

  In any case, there is the disadvantage that, if the level of noise or echoes exceeds the threshold level, erroneous detections and fluctuations occur, causing the loss of synchronization. For

  vertical, the synchronization the extractor with regard to the synchronization recovery of the output information is conventionally carried out in the following way: the vertical integrator, which generally comprises a resistor and a capacitor of large capacity (to accumulate long enough the charges synchronization pulses), provides a waveform that corresponds to the low-pass filtering of a vertical sync pulse (or LPF signal). This LPF signal is then sent to the vertical oscillator (a relaxation oscillator or a locked oscillator) whose function is to generate a sawtooth signal in phase with the vertical synchronization pulses. It generates this signal with a vertical period from the synchronization 2881601 6 slightly longer than the vertical frame period (a vertical stability adjustment potentiometer controls the eigenfrequency, or the clean period, of the sweep oscillator vertical). The upper part of the LPF wave, above a threshold, will trigger the oscillator to achieve vertical synchronization. The oscillator generates a ramp and waits for the threshold level of the next LPF signal. This conventional vertical synchronization therefore uses a threshold to detect a frame start position in the video signal and therefore, it is not robust to noise and echoes.

  In mobile communication systems, the signal level is often low due to the use of small omnidirectional antennas. As a result, the noise level is relatively high. In addition, the omnidirectional antennas are unable to reject the echoes due to the reflection of the broadcast signal and thus, for the reasons mentioned above, are conventional synchronization techniques particularly unsuitable for mobile applications.

  DISCLOSURE OF THE INVENTION The present invention therefore aims to overcome the disadvantages mentioned above, especially for mobile communication systems.

  More specifically, it is an object of the present invention to provide a vertical synchronization device for composite video signals that is significantly more efficient in the presence of noise or echoes than conventional devices.

  Another object of the present invention is to allow a regeneration of the horizontal and vertical synchronization of a composite video signal which is more robust to noise and which generates a better stability of the image.

  These and other objectives are achieved by a vertical composite video signal synchronization device adapted to receive a composite video signal input, comprising a signal extremum detecting means capable of detecting the position in time. of an extremum of the received video signal, determining a frame start position corresponding to the video signal received from the position of the detected extremum, and outputting a frame start position signal indicating the position of start of frame determined.

  Such a device makes it possible to improve the robustness of the vertical synchronization with the noise and the echoes because it does not use a synchronization extractor, and thus no threshold, to detect a starting position of frame in the video signal of synchronization extractor, but on the contrary it uses the detection of an extremum which is much less sensitive to noise, echoes and other spurious signals.

  Advantageously, the vertical synchronization device according to the invention further comprises a matched filter adapted to receive the composite video signal input, to filter the received video signal, and to deliver a filtered video signal corresponding to the input of the signal extremum detection means, the signal extremum detecting means being adapted to detect the position in time of an extremum of the filtered video signal.

  The use of a matched filter is preferable because the detection of an extremum (a minimum or a maximum) is simpler and more accurate to perform on a filtered video signal, which further improves the robustness to the noise and echoes of the synchronization device.

  The vertical synchronization device according to the invention may incorporate, in some of its variants, an extremum detection means that is adaptive, that is to say it is able to predict a future position of a next extremum of the video signal by calculating at what future time the extremum should be detected, from a position in the already detected time of a previous extremum. The extremum of the signal can then be searched more accurately and efficiently by observing the signal in a neighborhood of the expected position for that extremum. It is for example possible to use a video signal observation time window which is centered on the predicted position for the extremum.

  The vertical synchronization device according to the invention may furthermore comprise a line counter able to receive at the input a start-of-frame signal from the output of the signal extremum detecting means, to be received from the externally an input line start position signal, determining a frame line number N from the input signals and outputting a line number signal corresponding to the determined line number, the line counter being able to verify the validity of the line number from corresponding start-of-frame position and start-of-line position signals.

  With such a line counter, the synchronizing device is able to directly output a precise N-frame line number. In addition, the line number indicated at the output is not only that which is incrementally deduced from the line start position signals received from the outside, but the validity of this line number is checked using both the vertical and horizontal sync indications corresponding to the received composite video signal, such as, respectively, the start of frame position and the start of line position received at the input. This verification operation further increases the reliability of the delivered line number indication.

  In a variant of the preceding vertical synchronization device according to the invention, the signal extremum detecting means is furthermore able to receive a signal corresponding to a line number from the output of the line counter and to detect the position in the line counter. the time of a video signal extremum adaptively from the received line number signal 2881601. Indeed, the knowledge of a line number makes it possible to accurately predict the position in time of a future extremum of the observed video signal, all the more surely since this line number has been verified. In particular, when the extremum determination means implements a video signal observation time window, the line number indication delivered by the line counter makes it possible to center the window on the position expected for the extremum. very precisely because the line number makes it possible to exactly determine the start and end positions of the window. The calculation of the centering of the window no longer requires knowledge of the position in time of the previous detected extremum.

  The validation of the line number by the line counter according to the invention can be carried out using a valid frame counter which can be incremented or decremented according to the result of the comparison of a provisional line number. , corresponding to a line start position signal, and an observed line number, obtained from a corresponding frame start position signal and the line start position signal, and the value displayed by the valid frame counter.

  Advantageously, the adapted filter used at the input of the extremum determination means of the vertical synchronization device according to the invention may be a low-pass filter. Such a low-pass filter can indeed be considered as a simplified adapted filter. In this case, it is clear that the detected extremum is a minimum of the filtered video signal.

  The invention also relates to a device for regenerating horizontal and vertical synchronization of composite video signal adapted to receive a composite video signal input, comprising.

  a horizontal synchronization device adapted to receive the composite video signal input, to detect a line start position in the received video signal, and to loudly output a corresponding line start position signal indicating the line start position detected; a vertical synchronization device according to the invention, able to receive the composite video signal as input and to output a corresponding frame start position signal; and a synchronization regeneration module adapted to receive as input, respectively, the line start position signal outputted from the horizontal synchronization device and the frame start position signal outputted by the vertical synchronization device corresponding to the composite video signal received, outputting a regenerated horizontal synchronization signal in the form of a normalized horizontal synchronization signal given in phase, with a constant constant, with the received start of line position signal, and outputting outputting a regenerated vertical synchronization signal in the form of a normalized vertical synchronization signal given in phase, to a constant, with the received start frame position signal.

  The advantage of such a synchronization regeneration device is to use both the vertical and horizontal synchronization information to generate perfect synchronization signals (i.e. free of noise or echo distortion) and which are in phase, at a phase constant close (unlike randomly out of phase signals for example). These synchronization signals are normalized, i.e., they are standard, predefined signals, and characteristics of a transmission system (eg, NTSC or PAL / SECAM). Such signals may, for example, be stored in a memory of the device. This regeneration device is therefore robust to noise and echoes because it incorporates a vertical synchronization which has the advantage of not using a threshold for the received signal, and it also makes it possible to generate signals which are both standardized and which are each correctly in phase (with a constant close) with the corresponding source synchronization signal. Indeed, the regenerated horizontal sync signal is in phase (at a constant constant) with the line start position signal from the horizontal sync device and the regenerated vertical sync signal is separately in phase (at a constant constant) with the start-of-frame position signal from the vertical synchronization device, thereby obtaining images whose stability is improved.

  Of course, the synchronization regeneration device according to the invention may as well incorporate a vertical synchronization device which itself uses the start-of-line position information from the horizontal synchronization device (as described above). up) to output a signal indicating a line number.

  Such a synchronization regeneration device has the advantage over the previous one, in which the regenerated signals are. separately in phase (with a constant close) with the corresponding source signals but which can be out of phase with each other in a variable manner (or random), to deliver regenerated horizontal and vertical synchronization signals which are in phase with each other. This device is therefore also robust to noise but also makes it possible to obtain images whose stability is considerably improved because, unlike the prior art which performs a parallel processing of the horizontal and vertical deflection signals, the existing phase relationship between the horizontal and vertical scanning frequencies is used here.

  In this case, the invention therefore relates to a device for regenerating horizontal and vertical synchronization of composite video signal adapted to receive a composite video signal input, comprising.

  a horizontal synchronization device capable of receiving the composite video signal as input, detecting a line start position in the received video signal, and outputting a corresponding start position signal corresponding to the start position detected line; a vertical synchronization device according to the invention, able to receive as input the composite video signal and the corresponding line start position signal delivered by the horizontal synchronization device, and to output a corresponding line number signal; and a sync regeneration module adapted to receive as input, respectively, the line start position signal output from the horizontal sync device and the line number signal output from the vertical sync device corresponding to the received composite video signal. outputting a regenerated horizontal synchronization signal in the form of a normalized horizontal synchronization signal given in phase, to a constant, with the received start-of-line position signal, and outputting a vertical synchronization signal regenerated in the form of a normalized vertical synchronization signal given in phase with the regenerated horizontal synchronization signal delivered.

  Advantageously, a low-pass filter can be used as a simplified matched filter at the input of the extremum detection means in the vertical synchronization device forming part of the synchronization regeneration device (in this case, the detected extremum corresponds, of course, to a minimum).

  Finally, the invention also relates to a composite video signal receiver which incorporates the composite video signal synchronization regeneration device according to the invention. Such a receiver is therefore able to display on its screen images with significantly improved stability.

BRIEF DESCRIPTION OF THE DRAWINGS

  Figure 1 is an illustration of the logic diagram of a vertical synchronization device according to a first embodiment of the invention.

  Figure 2 is an illustration of the logic diagram of a vertical synchronization device according to a second embodiment of the invention.

  Figure 3 is a logic diagram illustrating the steps of enabling a line number in the vertical synchronization device according to the second embodiment of the invention.

  Figures 4 and 5 are illustrations of the processing of a composite video signal by the vertical synchronizer according to the second embodiment of the invention.

  Figure 6 is an illustration of the logic diagram of a vertical synchronization regeneration device according to a third embodiment of the invention.

  Figure 7 is an illustration of the logic diagram of a vertical synchronization regeneration device according to a fourth embodiment of the invention.

  DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS A first embodiment of the vertical synchronization device is illustrated in FIG. 1. The vertical synchronization device (10) receives a composite video signal (1) at the input and delivers a corresponding signal of line start position (7) at the output. The device (10) comprises a matched filter (2) which receives as input the composite video signal (1) and outputs the corresponding filtered video signal (3). The filtered signal (3) is then inputted by the signal extremum detection means (4), the latter comprises a detection module (8) which detects an extremum of the filtered signal (3) received, determines the position beginning of the raster line corresponding to the detected extremum, and delivering a corresponding signal of the start of line position (7). The module (8) operates in connection with an observation window position adjustment module (9), the module (8) sending an extremum position signal (5) detected in a filtered signal observation window (3) to the module (9) and receiving from the latter a window position signal (6) which allows the module (8) to adjust the position of the observation window on the expected position of the next extremum. At the beginning of the reception of the video signal (1), the module (8) uses a first observation window (corresponding to an initial setting of the window) which is sufficiently wide for the position in time of a first extremum can be detected, then the module (9) determines a width of the observation window, that is to say a duration of observation of the filtered signal (3), and this observation time is preferably chosen to be less than or equal to the duration of a frame, which makes it possible to avoid the detection of two extrema at a time corresponding to two successive frames in the window. Preferably, the width of the window is equal to the frame duration, which ensures that only one extremum will be detected for each received frame. The adaptation, for the detection of successive extrema, is then done by placing the center of the window on the position in time of the last detected extremum, corresponding to the received signal (5), increased by the length of a frame, that is to say on the expected position of the next extremum.

  A second embodiment of the invention is illustrated in FIG. 2, in which the elements corresponding to those of FIG. 1 are numbered in the same way.

  In this embodiment, the vertical synchronization device (20) further comprises a line counter (11) and outputs a frame line number signal (13) corresponding to a composite video signal (1) received in a Entrance. The device (20) has a signal end detector means (14) which receives a filtered video signal (3) as input and outputs a corresponding frame line start position signal (7). A line counter (11) receives the signal (7) and a line start position signal (12) from the outside which corresponds to the video signal (1) received at the input of the device (20). The line counter then delivers a line number signal (13) indicating the frame line number corresponding to the received signal (12). In the extremum detection means (14), the observation window position adjustment module (19) sends to the detection module (8) a window position signal (6) enabling the module (8) to set the position of the observation window to the expected position of the next extremum. The module (19) uses here the line number signal (13) to center the position of the observation window precisely because the indication of the frame line number makes it possible to deduce exactly, according to the transmission standard used. , the position in the start and end time of the observation window of the filtered signal to observe the next extremum. The line counter (11) checks the validity of the line number which it determines, from the received signals (7) and (12), before sending the signal (13).

  The validity check can be performed according to the steps of a logic diagram illustrated in Figure 3, using a valid frame counter. In this case, the line counter (11) in the vertical synchronization device (20) comprises a valid frame counter VFC for displaying a number of valid frames V, initialized to zero (V = 0), and the counter (11) is also able to calculate a provisional line number N1 for each received line start position signal (12), to determine an observed line number N2 from the comparison of each position signal of received start of frame (7) and of each received incoming line start position signal (12), comparing the calculated provisional line number N1 and the determined observed line number N2 corresponding to the same start position signal of frame (7) received and, if these numbers Ni and N2 are equal then the displayed value V by the valid frame counter VFC is incremented (V = V + 1) and the line number N determined by the line counter (11 ) is equal to the line number provisional N: L (N = Ni), if these numbers N1 and N2 are different then: - if the value displayed by the valid frame counter VFC is greater than zero (V> 0) the value displayed by the counter of valid frames VFC is decremented (V = V - 1) and the line number N determined by the line counter (11) is equal to the provisional line number N1 (N = N1), - otherwise, the line number N determined by the line counter (11) is equal to the observed line number N2 (N = N2).

  The valid frame counter may advantageously be saturated at a given maximum value (for example at 20) to avoid a too long response time in the case of television channel switching. This saturation value Vmax is related to the frame frequency f by the relation Vmax / f = C, where C denotes a time constant which indicates the maximum time necessary for the resetting of the vertical synchronization by the passage of the counter of valid frames to zero.

  FIGS. 4 and 5 illustrate the processing of an NTSC-type composite video signal (1) by the vertical synchronization device (20) according to the second embodiment of the invention, in which a low-pass filter takes the place of simplified adapted filter and wherein the extremum detection means (14) detects a minimum of the filtered signal (3) by this low-pass filter.

  In FIG. 4, whose horizontal axis represents the time graduated in number of lines since the beginning of the recording and the vertical axis indicates amplitude values of the received composite signal (1), the filtered video signal (3 ) is superimposed on the composite video signal (1), the circles indicated on the curve of the filtered signal (3) correspond to line start position signals (12) and the numbers indicated at the circles are the corresponding line numbers. . A cross in the vicinity of the line number 7, on the curve of the filtered signal, indicates the location of the minimum of the detected signal (3).

  In the case of Figure 5, which also shows the filtered signal (3) superimposed on the composite signal (1), the location of the minimum detected by the module (8) is in the vicinity of the line number 269.

  These line numbers 7 and 269 (respectively in FIGS. 4 and 5) correspond to observed line numbers (N2).

  The determination of a line number N2, said to be observed, is carried out as follows, in the case of an NTSC system with 525 lines per image: the time positions of the line signals (12) are compared with of detected weft (7), if the position of the minimum corresponding to the start-of-frame position signal (7) (or of the extremum in the general case) corresponds to a beginning of the line position (indicated by the signal (12 )) then line number 7 of the frame is observed (with an error margin corresponding to '4 of line), if there is a shift of half a line between the vertical minimum and the position of the beginning of the line then line 269 is observed. In the case of a PAL / SECAM system, that is to say in a system with 625 lines per image, if the position of the minimum corresponds to a position of beginning of line then the line number 316 is observed, s' there is a shift of half a line between the vertical minimum and the position of the beginning of the line, then the line number 3 is observed.

  A third embodiment of the invention is illustrated in FIG. 6 and corresponds to a vertical and horizontal synchronization regeneration device (40). The device (40) comprises a horizontal synchronization device (30), a vertical synchronization device (31) and a synchronization regeneration module (32). The device (40) receives an input. composite video signal (1), this signal is also inputted by the devices (30) and (31), and outputs a corresponding regenerated synchronization signal (33).

  The horizontal synchronizing device (30) (which may be a conventional device) then outputs a line start position signal (12), corresponding to the signal (1), to a first input of the regeneration module (32). . The vertical synchronization device (3: L), that is. a device according to the invention (for example the device (10) described above), delivers a frame start position signal (7), corresponding to the signal (1), to a second input of the regeneration module (32) . The regeneration module (32) has a memory in which are stored normalized horizontal synchronization and normalized vertical synchronization signals (these normalized signals of course correspond to the signal transmission standard (1)). The regeneration module (32) then outputs a regenerated synchronization signal (33) which is in the form of the horizontal synchronization signal normalized in phase, to one constant, with the signal (12), or in the form of a vertical synchronization signal normalized in phase, with a constant constant, with the signal (7). The standardized signals sent have been read into the memory of the module (32) (for example upon receipt of the corresponding synchronization signal). The regenerated horizontal and vertical synchronization signals delivered by the device (40) may still have a variable phase difference between them, which depends on the phase difference existing between the input signals (12) and (7).

  To overcome this drawback, a fourth embodiment of the invention is illustrated in FIG. 7. This mode corresponds to a vertical and horizontal synchronization regeneration device (40b). The device (40b) also comprises a horizontal synchronization device (30), a vertical synchronization device (31b) and a synchronization regeneration module (32b). The device (40b) receives as input. composite video signal (1), this signal is also inputted by the devices (30) and (31b), and outputs a corresponding regenerated synchronization signal (33b).

  The horizontal synchronization device (30) then delivers a line start position signal (12), corresponding to the signal (1), to a first input of the regeneration module (32b). The vertical synchronization device (31b), which is a device according to the invention comprising a line counter (11) such as, for example, the device (20) described above, delivers a frame line number signal ( 13), corresponding to the signal (1), to a second input of the regeneration module (32b). The signal (12) is also inputted by the vertical synchronizer (31b). The line counter (11) according to the invention is able to deliver the signal (13) from the signal (12) and a frame start position signal (7) from the extremum detection means ( 14) and corresponding to the signal (1), as has been described above.

  The regeneration module (32b) then outputs a regenerated synchronization signal (33b) which is in the form of the normalized horizontal synchronization signal or in the form of a normalized vertical synchronization signal, the horizontal synchronization signal 2881601 standardized and standardized vertical synchronization being in phase with each other. The normalized synchronization signals for each frame line are stored in memory, and the signal line number indication (13) allows the regeneration module (32b) to search and find in the memory the normalized synchronization signal which corresponds to this line number, then, from the reception of the line start signal (12), to generate the corresponding normalized signal found in memory. The signal start indication of the signal (12) triggering the transmission by the module (32b) of the corresponding normalized signal. This device (40b) thus makes it possible to have a horizontal synchronization signal and a regenerated vertical synchronization signal which are in phase with one another.

  Advantageously, the device (40b) has a regeneration module (32b) which is able to associate with each line number signal (13) received a given normalized vertical synchronization signal corresponding to the line number, and to deliver, upon receipt the start-of-line position signal, the associated normalized vertical synchronization signal.

  Normalized vertical and horizontal sync signals are in phase.

  Of course, the invention is not limited to the embodiments described above which have been given only as examples. Thus, several modifications and / or improvements can be made to the devices according to the invention without departing from the scope thereof.

Claims (1)

26 CLAIMS   1. A device for synchronizing a composite video signal vertically (10, 20) capable of receiving, as input, a composite video signal (1), characterized in that it comprises a means for detecting a signal extremum (4, 14) capable of detecting the position in time of an extremum of the received video signal, determining a frame start position corresponding to the video signal received from the position of the detected extremum, and outputting a position signal of start of frame (7) indicating the determined start of frame position.   Vertical synchronization device according to claim 1, further comprising a matched filter (2) adapted to receive the composite video signal (1) as input, to filter the received video signal, and to output a filtered video signal (3). corresponding to the input of the signal end detection means (4, 14), the signal end detection means (4, 14) being able to detect the position in time of an extremum of the video signal filtered (3).   A vertical synchronization device according to claim 1 or 2, wherein the signal extremum detecting means (4) is adapted to detect the temporal position of an extremum of the video signal adaptively from the position in the detected time of a previous extremum of the video signal.   4. Vertical synchronization device according to claim 3, wherein the signal extremum detection means (4) is able to detect the position in time of an extremum of the video signal in a time window of observation of the signal. the time position of this window being set to a position in time of an extremum of the signal which is calculated from the position in the detected time of a previous extremum of the signal.   5. Vertical synchronization device according to any one of claims 1 to 4, further comprising a line counter (11) adapted to receive as input a start frame signal (7) from the output of the detection means. signal extremum (4, 14), to receive from the outside a line start position signal (12) at the input, to determine a frame line number N from the input and output signals at the output a line number signal (13) corresponding to the determined line number, said line counter (11) being able to check the validity of the line number from corresponding start frame position signals (7) and inbound line position (12) received as input.   6. Vertical synchronization device according to claim 5, wherein the line counter (11) comprises a valid frame counter previously initialized to zero and is capable of calculating a provisional line number N1 for each line start position signal. (12) receiving, determining an observed line number N2 from the comparison of each received start frame position signal (7) and each received incoming line start position signal (12), comparing calculated provisional line number N1 and the determined observed line number N2 corresponding to the same received frame start position signal (7) and, if these numbers Ni and N2 are equal then the value displayed by the valid frame counter is incremented and the line number N determined by the line counter is equal to the provisional line number N1, if these numbers N1 and N2 are different then: if the value displayed by the account If the number of valid frames is greater than zero, the value displayed by the valid frame counter is decremented and the line number N determined by the line counter is equal to the provisional line number N1, otherwise the line number N determined by the line counter is equal to the observed line number N2.   The vertical synchronization device according to claim 6, wherein the valid frame counter is saturated to a given value.   The vertical synchronization device according to claim 1 or 2, further comprising a line counter (11) adapted to receive as input a frame start position signal (7) from the output of the extremum detection means of signal (14), externally receiving an input start line signal (12), determining a frame line number N from the input signals and outputting a signal line number (13) corresponding to the determined line number, said line counter (11) being able to check the validity of the line number from corresponding start frame position signals (7) and start position line (12) received at the input, said signal extremum detecting means (14) being further adapted to receive a signal (13) corresponding to a line number from the output of the line counter (11) and to detect the position in time of an ext adapting video signal adaptively from the received line number signal (13).   9. Vertical synchronization device according to claim 8, wherein the signal extremum detection means (14) is able to detect the position in time of an extremum of the video signal in a time window of observation of the signal. the time position of this window being set to a position in time of an extremum of the signal which is calculated from the received line number signal (13).   Vertical synchronization device according to claim 8 or 9, wherein the line counter (11) comprises a valid frame counter previously initialized to zero and is capable of calculating a provisional line number N1 for each start position signal. line (12) received at. determining an observed line number N2 from the comparison of each received start frame position signal (7) and each received incoming line start position signal (12), to compare the calculated provisional line number N1 and the observed line number N2 determined corresponding to the same received frame start position signal (7) and, if these numbers Ni and N2 are equal then the value displayed by the valid frame counter is incremented and the line number N determined by the line counter is equal to the provisional line number N1, if these numbers Ni and N2 are different then: if the value displayed by the valid frame counter is greater than zero, the value displayed by the valid frame counter is decremented and the line number N determined by the line counter is equal to the provisional line number N1, otherwise the line number N determined by the line counter is equal to n observed line number N2.   The vertical synchronization device according to claim 10, wherein the valid frame counter is saturated at a given value.   Vertical synchronization device according to any one of claims 2 to 11, in which the matched filter (2) is a low-pass filter and the signal extremum detection means (4, 14) is a means of signal minimum detection capable of detecting the position in time of a minimum of the filtered video signal (3).   13. Composite video signal synchronization regeneration device (40) adapted to receive as input a composite video signal (1), characterized in that it comprises: a horizontal synchronization device (30) able to receive the signal input composite video (1), detecting a line start position in the received video signal (1), and: outputting a corresponding line start position signal (12) indicating the detected line start position; the vertical synchronization device (31) according to any one of claims 1 to 4, adapted to receive as input the composite video signal (1) and outputting a corresponding frame start position signal (7); and a synchronization regeneration module (32) adapted to receive as input, respectively, the line start position signal (12) output from the horizontal synchronization device (30) and the frame start position signal (7). ) output by the vertical synchronization device (31) corresponding to the received composite video signal (1), outputting a regenerated horizontal synchronization signal in the form of a given horizontal normalized synchronization signal in phase, to a constant, with the received line start position signal (12), and outputting a regenerated vertical synchronization signal in the form of a normalized vertical synchronization signal 2881601 32 given in phase, at a constant near, with the received start of frame position signal (7).   14. Composite video signal synchronization regeneration device (40b) adapted to receive as input a composite video signal (1), characterized in that it comprises.   a horizontal synchronizing device (30) adapted to receive the composite video signal (1) as input, detecting a line start position in the received video signal, and outputting a corresponding start position signal (12); line indicating the detected start of line position; the vertical synchronization device (31b) according to any one of claims 5 to 11, adapted to receive as input the composite video signal (1) and the corresponding line start position signal (12) delivered by the synchronization device horizontal (30), and outputting a corresponding line number signal (13); and a synchronization regeneration module (32b) adapted to receive as input, respectively, the line start position signal (12) output from the horizontal synchronization device (30) and the line number signal (13) issued by the vertical synchronizing device (31b) corresponding to the received composite video signal (1), outputting a regenerated horizontal synchronization signal in the form of a normalized horizontal synchronization signal given in phase, at a constant time of 2881601; , with the received line start position signal (12), and outputting a regenerated vertical synchronization signal in the form of a given normalized vertical synchronization signal in phase with the regenerated horizontal synchronization signal delivered.   15. Synchronization regeneration device according to claim 14, wherein the synchronization regeneration module (32b) is adapted to associate each received signal number signal (13) with a given normalized vertical synchronization signal corresponding to the line number. , upon delivery of the line start position signal (12), outputting the associated normalized vertical synchronization signal.   Synchronization regeneration device according to any one of claims 13 to 15, wherein the matched filter (2) of the vertical synchronization device (31,31b) is a low-pass filter and the extremum detection means signal of the vertical synchronization device is a signal minimum detection means adapted to detect the position in time of a minimum of the filtered video signal (3).   17. Composite video signal receiver characterized in that it incorporates the composite video signal synchronization regeneration device according to any one of claims 13 to 16.