Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N7/00—Television systems
  • H04N7/025—Systems for the transmission of digital non-picture data, e.g. of text during the active part of a television frame
  • H04N7/035—Circuits for the digital non-picture data signal, e.g. for slicing of the data signal, for regeneration of the data-clock signal, for error detection or correction of the data signal
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N7/00—Television systems
  • H04N7/08—Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band, e.g. by time division
  • H04N7/087—Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band, e.g. by time division with signal insertion during the vertical blanking interval only
  • H04N7/088—Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band, e.g. by time division with signal insertion during the vertical blanking interval only the inserted signal being digital
  • H04N7/0887—Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band, e.g. by time division with signal insertion during the vertical blanking interval only the inserted signal being digital for the transmission of programme or channel identifying signals

Definitions

• the invention relates to a system according to the preamble of the claim.
• a system of this type is known from "Rundffunkchnic Mitteilungen", vol. 16 (1972), number 2, pages 90 and 91.
• Radio communications communications 16 (1972) number 2, pages 90 and 91) is based on the simultaneous use of a complementary pair of lines, namely the lines 16 and 329 for one and the same data, as can be seen in Figures 5 and 7 of this publication.
• each of the two blanking lines 16 and 329 was assigned a separate "service": line 16 became source-related, line 329 section-related data line for internal identification and monitoring purposes. This also made it necessary to make a field selection on the receiving side in order to be able to distinguish between the two services, which use an identical data format including the start code.
• VPS system also assumes these conditions (Technical Guideline ARD / ZDF No. 8 R 2, 1st edition Dec. 84 / Febr. 85). There, in addition to the field selection, a windowing on line 16 is required (page 7 of this guideline), in particular in order to exclude the teletext data transmitted in the same field.
• a disadvantage of this decoding concept is first of all the noteworthy additional outlay for an amplitude sieve for separating the synchronous signal mixture from the video signal and also for a device for selecting the odd field and finally for a line counter.
• the devices for field selection often work relatively unreliably when they are offered video signals that are contrary to standards, e.g. those with luminance components below black in the area of the last active lines of a field.
• VPS decoders would function independently of the line or field position of the associated biphase data line, that is if any blanking line could be used for VPS transmission, and without Variation of a selection criterion on the decoder.
• the object of the present invention is to provide a system for the transmission and decoding of biphase data which, in the case of a fixed decoder configuration, permits the free choice of the line and field position for the data line used, nevertheless high protection against confusion against others which simultaneously transmit in the same video signal ⁇ offers data services and also reduces the effort in the decoder.
• the invention is explained in more detail with reference to the drawing.
• the figure shows a block diagram of a data line decoder suitable for the system according to the invention.
• the video signal 11 supplied to the decoder input 1 contains, as is the case in reality, several independent data services in its vertical blanking interval, for example NP.Z-coded video text codes in a few lines, and for example two biphase-coded services, for example one in-house (of Broadcasting and / or post) used section data line and the source data line used for VPS.
• NP.Z-coded video text codes in a few lines
• biphase-coded services for example one in-house (of Broadcasting and / or post) used section data line and the source data line used for VPS.
• position it must be irrelevant for the decoder of the respective service in which line position the data of the service in question are transmitted.
• each biphase-coded data service must use an individual start code.
• the VPS and source data line can use the bit element pattern defined in the VPS specification
• Both patterns must violate the antivalence rule valid in the useful data area, e.g. contain three logical zero elements or three logical one elements in succession.
• the entire video signal 11 is fed directly to the data separation stage 2 and also to the clock processing stage 3 without field field windowing and one line deletion.
• the latter derives the associated system clock from the data sequence and provides it at its output 32 in the correct phase to the data present at the data separation stage 2 at its output 22.
• a level discriminator with an optionally adaptively controlled decision threshold at 50% of the video data amplitude serves as data separation stage 2.
• the video signal 11 shaped in this way to form the two-phase signal 11 ' is no longer subjected to field window or line windowing in the further course of the decoding process, but rather directly to the start code checking device 4, the antivalency checking device 5 and the buffer memory 6 together with the system clock from output 32.
• the start code checking device 4 contains e.g. a binary comparator, to which the start code bit element pattern (see above) of the biphase service to be decoded is constantly applied, and whose actual value inputs are connected to the outputs of a parallel input slider video signal 11 '. If the setpoint and actual values are the same, the presence of the true start code in the assigned data line or even just a supposed start code is signaled at the output 41 as a random constellation, for example in a video text line or even in its image content line.
• a binary comparator to which the start code bit element pattern (see above) of the biphase service to be decoded is constantly applied, and whose actual value inputs are connected to the outputs of a parallel input slider video signal 11 '. If the setpoint and actual values are the same, the presence of the true start code in the assigned data line or even just a supposed start code is signaled at the output 41 as a random constellation, for example in a video text line or even in its image content line.
• the equality signal at the output 41 reports via the input 51 of the antivalence test device 5 the phase of the bits to be compared from now on (a detailed explanation can be found in the German patent specification DE 30 20 530) and is also supplied to the control logic 7. This is so designed that only aan at the control logic output 73 a takeover pulse occurs if between Star code detection at input 71 and at the end of the transmission of the last useful bit (ie after 208 systems from start code message), no unique antivalence sensor has been signaled via input 72.
• the take-over pulse from the output 73 causes the data temporarily stored in the buffer 6 in the course of the data transfer to be transferred to the output memory 8 and is available at its output 81 as information which has been checked for errors and service assignments.
• start code checking device 4 could incorrectly hold for a biphase data line due to the lack of a window, for example, a video text line or image content lines.
• the 16 elements of the start code require a probability of 1: 65000 for such an implementation, which can worsen if spectrally similar random data signals such as teletext are to be excluded. This is not sufficient for secure decoding.
• the first useful word one does not rely on the fact that this word itself does not show an active error - this could also happen to cause a video text line. Rather, the first useful word is only regarded as belonging to the desired service and as being transmitted incorrectly, even if none of the most important twelve useful words has not been de-tected.

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• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Television Systems (AREA)
• Detection And Prevention Of Errors In Transmission (AREA)
• Basic Packing Technique (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 1990
  • 1990-06-23 DE DE4020066A patent/DE4020066A1/de active Granted
• 1991
  • 1991-06-15 WO PCT/EP1991/001117 patent/WO1992000648A1/de not_active Ceased
  • 1991-06-15 EP EP91911220A patent/EP0536188A1/de not_active Ceased
  • 1991-06-15 AU AU79687/91A patent/AU7968791A/en not_active Abandoned
  • 1991-06-15 HU HU923810A patent/HUT63019A/hu unknown
  • 1991-06-15 JP JP91510541A patent/JPH05508063A/ja active Pending
• 1995
  • 1995-09-07 US US08/524,730 patent/US5627595A/en not_active Expired - Lifetime

Non-Patent Citations (1)

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