DE2820150A1 - SYSTEM FOR TRANSMITTING ADDITIONAL DATA, IN PARTICULAR TELETEXT DATA, BETWEEN A ROW OF TELEVISION LINES AND RECEIVERS OF A PAL OR SECAM TELEVISION SIGNAL - Google Patents

Description

Note: INDESIT INDUSTRIA ELETTRODOMESTICI ITALIANA SpA Str.Piossasco, Km 17
I-Rivalta, Turin

System for transferring additional data, in particular Teletext data, between a series of television lines and the receiver of a PAL or SECAM television signal

The invention relates to a system for transmitting and receiving additional data between a series of television lines of a PAL or SECAM color television signal, especially a PAL or SECAM television receivers and an encoder for introducing additional data relating to pages of written text and / or graphic representations.

An experimental version of this system is currently in use in the UK and a number of others Countries tested, including in West Germany and Italy. This system is known as a teletext, other similar systems are called Ceefax or Oracle. In the teletext system, data is stored in Reference to a number of pages of written text or graphical

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phical representations (up to 100 different pages), each consisting of 24 lines of 40 characters, set in digital code (ISO 7) using the NRZ system, and the picture during two lines (e.g. 15 and 16) - Transmit blanking period of a normal CCTR television signal »During each picture, the data relating to two lines of text is transmitted, and each is preceded by:

1) an EIMLAUE

2) a BILDOODS

5) a line address

If you love the decoding system, the receiver has a memory to record all lines on each page and a character generator to disp ^ ing the various texts or graphic representations.

The timer frequency used is 6.9375 megabits / second. The operation of this system is because of the high level of accuracy that the receiver must be designed for in order to regenerate the timer frequency, and because of the high level of accuracy . relative rarity of the data (only two EHiLuUl ¹ E per image, each with eight oscillations) somewhat critical.

These two reasons (high level of accuracy needed and rarity of sync data) explain the complexity, high cost, and poor reliability of timer regenerators, what not to be because television receivers are commodities that are mass-produced at low cost have to.

In OOIR countries the frequency is 6.9375 megabits / second for the television channel width used (7 MHz in total)

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and the normal iaßband on receivers too high, what the Makes operation unreliable.

The invention is based on the object of at least partially solving the problems that arise in the known teletext system cling. To solve this problem, according to the invention, a system for overlaying additional data between a series of television lines within the field blanking period a PAL or SECAM Parb television signal provided, which is characterized in that the additional data on pages of font textßB or graphic Relate representations and in the 3? Orm digital iniptile sequences with a certain timer frequency are provided in combination with additional pulse sequences that contain control and synchronization data, and that the selected time frequency equals the frequency of an auxiliary carrier or the same as the auxiliary carrier plus or raindus a multiple of the line frequency.

The invention is based on the fact that a normal

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Color television signal, for example, the well known PAL system signal, highly accurate, contains reliable frequency data, to be more specific, the Farbsynchronisierun _t; sdaten, to Eerinn almost äfl.er television lines in the form of a so-called "burst" of 10 oscillations at the Farbhilfsträ ^. frequency can be transmitted.

As is known, the frequency of the subcarrier in the PAL system is 4.43361875 WHz. The type of burst is such that it is a Has a spectrum with a plurality of spectrum lines that are spaced about 7.8 MHz apart, in the case of the PAL system, and 15.6 HHz if the phase jump of the PAL system is suppressed.

A time: overfrequency for the ^r JS.etext signal can therefore be selected so that it is equal to one of the aforementioned lines: For example 6.43361875 HHz, which corresponds to the 156th line in the alternating burst spectrum and the 128th iu non-alternating spectrum (4433617 , 75 +128 χ 15626 = 6433617.75) · It is known that not all of these spectrum lines have the same amplitude, but that they form a kind of soffit curve. The distance between the smallest and the largest is the reverse of the burs £ län ;; e. Of course, it is advisable that the frequency be regenerated to correspond to a maximum. The frequency given above corresponds more or less to a maximum. In this way it is possible for the timer regenerator within the receiver to be synchronized by the burst position of the JillfliAUFS in order to improve the reliability of the kegeneration circuit.

The EIWLAUF signal can even be omitted.

With a timer frequency of 6.43361875 megabits / second and no ENTRY signal, a total of 41 characters

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can be set up per line (52 χ 6.43361875 = 334.5 / = 41.3), which corresponds to 38 actual text characters, as explained below:

Continuing along these lines, it is even possible to set a frequency of 4.43361875 WhZ for the color subcarrier oscillation (instead of 6.9375 14Hz) as a timer frequency for the To use teletext signal.

Using this lower frequency is the receiver bandwidth no longer a problem because each recipient has a bandwidth that is sufficient for reception.

The burst (the normal color sync signal) is usually transmitted at the beginning of each line whenever color signals are transmitted. The invention provides for the transmission whenever teletext signals are transmitted. In the case of transmission of a TV signal using the known PAL system is derßurst for color appearance phase alternating and non-alternating (fixed phase or from PLL) for Teletextübertragun- ■; s in black and white. The "color lock" on PAL color receivers works normally insofar as it is controlled by the alternating 7.8 KHz burst. The telex text data can be in color even when normal viewing is in black and white.

When equipped with a decoder and timer regenerator, even a normal black / white receiver is used Able to receive the 'free ext signal (in black / white). By transmitting the burst every line, the timer regenerator is significantly less complex than in the case of • only two INPUT signals per image. Furthermore color television sets are already equipped with a regenerator in the form of a normal color subcarrier regenerator.

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At a timer frequency of 6.9375 megabits / second typically records a line of 52 microseconds: 52 χ 6.9375 3 = 360 bits or 360/8 = 45 characters each with 8 bits (7 data bits and 1 parity bit).

These 45 characters are used as follows:

- 2 for the BINIAUF

- 2 for the BILDGODE

- 2 for the line address

- 40 for the text

I4it can operate at a frequency of 4.43361875 megabits / second record a 52 microsecond line:

52 χ 4.43361875 = 230 bits or 230/8 = 28 characters.

Because ENTRY ^{1 is} no longer required, these 28 characters can be used as follows:

- 1 for the BILDGODE

- 2 for the line address

- 25 for the text
Or:

- 1 for the BILDCODK

- 2 for the line address

- 5 for other codes or checks

- 20 for the text

In the first pail you can use 4 lines of TV per picture (e.g. 15, 16, 20 and 21) 50 characters per line of text ^ e 40 are transmitted in the second pail, i.e. the number sent continuously. The five additional characters can be used to send additional codes (e.g. as opposed to transferring the page number in each line at the beginning of each page as currently handled), as well

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for more sophisticated bug checks.

For the page title at the beginning of each page, in addition to the normal control signals (EINLAUF, BILI) GODE, address) 8 additional control characters are continuously transmitted. The '.iitel therefore consists of:

- 5 normal control characters (including EINLAUi ¹ )

- 8 special control characters

- 32 characters

The system according to the invention consists of:

- 3 normal control characters

- 8 special control characters

- 17 Ί ¹ ext character
or:

- 3 normal control characters

- 9 special control characters

- 16 characters

Obviously, this is a great advantage to simplify both the encoder (the timer oscillator is replaced by the existing subcarrier oscillator) and also of the decoder (the timer regenerator is no longer needed, for the same reason if it is a Lyirb apparatus).

The reliability is also improved because of:

the use of a low frequency for the timer;

- the transmission of a much stronger synchronous signal (Burst) for the timer;

- the! 'solubility of introducing additional control characters »

The only condition to achieve all of these benefits

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is to use four television lines per picture instead of 2. Because these lines are already available, it's just a matter of designing the encoder and the Decoder in such a way that the former converts the first half of a particular line of text into a particular line of television of the picture rewind (e.g. line 15) and then, following the control characters, the second half of the same Line of text in the next following line of the TV (e.g. line 16). Following the control characters, the Enter the first half of the next line of text in another preselected television line (e.g. line 20) and follow it up at the control characters the second half of the same line of text in the next following television line (e.g. line 21) and so on (e.g. the first half in line 328, the second half in line 329} the first half in Row 333, the second half in cell 334, and so on).

In the decoder, the same puncture is performed in reverse, i.e., by pairing the two half-text lines for reconstruction of the original. The decoder is provided with a one-page memory into which the data is gradually transferred fed in while receiving and decodingfc to show the entire sheet.

Instead of receiving one line at a time, this is in accordance with the invention System designed to receive the text in half lines through the memory. Definitely receives the memory always has two complete lines of text per image. So far only the case has been considered which is is a PAl color television signal. However, what also applies has so far been carried out, with changes, for other color television systems. Take the SECAM system, for example (registered trademark) used in France

The SECAM system is a frequency-modulated sequential

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system in which two different frequencies, known as "red frequency" (4.40625 MHz) and "blue frequency" (4.25 MHz) are known to be broadcast alternately at the beginning of successive television lines. During the scrolling (Lines 7-15) are also special identification bursts According to the invention, the teletext signal can be sent under Using the frequency of 4.40625 megabits / second as the timer frequency (or a frequency with a multiple of the line rate, i.e. a multiple of 15625 Hz away from it). The frequency can be set in the receiver of 4.40625 IiHz, which is available at the beginning of the "red lines" using a known electronic gate circuit which is synchronized by the identification system in the apparatus and with the half Line frequency works. This "red frequency" is then sent to the timer regenerator.

In the case of black and white transmissions with additional i'eletextsignalen becomes the "red frequency" of 4.40625 MHz transferred at the beginning of each line.

In this way:

- the color lock in the device is activated and the color channel is deactivated;

- the timer regenerator receives the sync signal, in any case, from the frequency of 4.40625 MHz, even if the half-line frequency gate circuit is not identified will.

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The invention is illustrated below with the aid of exemplary embodiments explained in more detail with reference to the drawings. In the drawings are:

1 shows the data format and position for a series of transmission lines in accordance with the invention ,

2 shows a block diagram of a signal decoder after the link finding,

3 is a more detailed block diagram of part of the circuitry of Pig. 2 \

Figure 4 is an illustration of schematic diagrams of waveforms in the Pig circuit. 3 and

5 is a block diagram of a signal receiver according to the invention.

The following description now gives a better way and Way to use the characters that are made available in the system, and are particularly simple in it Circuit arrangements specified in order to undertake the signaling and the decoding according to the invention.

In Pig. 1, A, B, O and D denote four lines of data, the

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each in digital code during the line blanking period in the field blanking interval of an OCIR normal television signal be sent. The digits 1 Ms 25 "denote successive groups of 8 bits, 1 each represent a specific piece of data, usually an ISO-7 code character with a parity bit. The lines A and B contain information relating to the page title, and lines G and D contain information relating to a line of data. In detail, bit no. 1 in line A represents the start code (STR) or the BILDCODE, Wr. 2 and 3 the line and Magazine address (ADR), No. 4 and 5 the page address units (PNU) or tens (PNZ), No. 6, 7, 8 and 9 the time data, Minutes of one (TI-IU) and tens (TMT), hour of one (THU) and tens (THT), No. 10 and 11 control characters (OTL) and No. 12-25 (ORT) the first 14 characters of visual data in relation to the page title. In line B, which is sent immediately afterwards, bits are no. 1, 2 and the same as in the previous line, bits # 4 and 5 are free, while bits # 6-25 are the next Contains 20 text characters. In line 0, bits no. 1 to 5 are the same as in line A, while 6 to contain the first 20 text characters. In row D, bits 1 to 3 are the same as in row C, 4 to 5 are free, and bits 6 to 25 contain the second group of 20 text characters.

The start or picture code that is sent on each line is represented by the binary sequence 11100100. The line address is zero for the page title or a number between 1 and 24 for lines of text. The page address is a digit between 0 and 99, every two transmission lines is introduced at the beginning of the text and which is the same for all lines on the same page. The time and control signs are introduced at the beginning of each page heading. In Pig. 2 supplies the video signal generator 1

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a video output signal (S) to a synchronous stage circuit 2, a burst separation stage 4 and a. Adding stage 5c Me Separation stage 2 supplies a horizontal frequency signal (H) to the gate signal, ^; enerat or 3 and the buffer circuit 6 and a vertical frequency signal (V) to a control circuit 7 and the generator 3, which in turn is a switch-on signal (V /) to circuit 6 and a burst key signal to the separator 4 and a first input of an AND gate circuit 12 supplies. The circuit 7 has a data input (IN), a data and steep output (DP) and an address output (AD), Both outputs are connected to the data memory 8 and the circuit 6, the output (DS) of which via a low-pass filter. 9 is connected to the Addier.stufe 5, at its Output (OUT) the final signal is made available. The outputs DP and AD have more than one Connecting line and that is why they are drawn with a dioecious black line. This symbolism is also repeated in Figures 3 and 5, which follow will still have to be described.

The output of the isolating stage 4 is connected to an auxiliary carrier power generation circuit 10 and connected to an amplitude detector 11. The output of the latter is connected to a second inverting input via the gate circuit 12, whose Output via a bandpass filter 13 is connected to the adder 5, while the output of the circuit 10 with a third uingan ;; the gate circuit 12 is also connected to the circle 6.

Regeneration circuit 10, Another way of working consists in separating stage 2 and the T. which are drawn in dashed lines to deactivate or leave out In this jj'all the signals H, V, S and C supplied directly from generator 1 (dashed line).

The encoder in Fig. 2 operates as follows:

Ground the horizontal and vertical sync signals H and V v /

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separated by the separation stage 2 from the PAL Earbvideosignal at the output of the video generator 1. They are then processed by the generator 3 to provide a gate signal for the burst and to generate a switch-on signal for introducing the teletext signal into the required television lines. The separating stage 4 then separates the color subcarrier synchronous burst from the complete video signal in order to obtain a phase input of the Regenerierkreisep 10 at a frequency of 4.43361875 MHz, while the gate circuit 12 is held by the amplitude detector 11 out of stink. When incoming data are received, the control circuit 7 makes any necessary adjustments to the content of the data memory 8 and also picks up the data for the transmission from the memory (two lines of text) during the active picture period. These are then transferred to the buffer circuit 6 _; from which they are subtracted later on the upstream lines during the frame rewind with the time '-; overfrequency of the generator 10 (signal DS), are filtered through the low-pass filter 9 and are added to the original video signal in the adder stage 5.

In this way there is a complete video signal at the output The Addierstufe5 sur made available, the additional Contains data relating to pages of text.

There are no bursts at the Ause ^ an: -: of the separation stage 4 in the Ü! \ Ilse of a black / white signal. This leaves the regeneration circuit 10 free (although it continues to oscillate at close to the color subcarrier frequency) which further controls the data transmission rate. At the same time, the detector 11 turns the gate circuit 12, which for the band-pass filter 13 roughly ten cycles per line of the regenerating ~ kreisiO transmits, i _n then the other signals represent the adder 5 to be added,

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The result is an output signal, the bursts of fixed phase the UTSC type contains

j? y. Fig. 3 shows details of the circuits shown in blocks 6, 7 and 8 in Jj ¹ If ". 2. The signals and circuits that are the same as those in Pig, 2 are denoted by the same letters and numbers. The timer sense C becomes through the delay circuit 35 to the timer input ;; (CP) of the flip-flop circuit 33 and through the AND gate circuit 20 to the timer input (CJ?) of the x8 counter 21. The first two outputs of this counter are connected to the address inputs of RAM memories 29 and The third output is connected via an AND gate circuit 22 to the timer input (CP) of a second 5-bit counter 23, with a third Input of the gate circuit and connected through the inverter 24 to a further address input pcxi -'-, the RAM 29 and 30 and to the converter 31. The line frequency signal H becomes the timer input (CP) of an x 4 counter 26 and sent to the reset input (R) of the counter 21 and the counter 23, the 5 outputs of which are connected in numerical sequence to the 5 inputs of the AND gate circuit 27, of which the second and third inverter inputs are, furthermore to further addresses The output of the gate circuit -27 is connected to the second input of the gate circuit 20, to the fourth input of the gate circuit 25 - both inverting inputs - and to the control input (S) of the flip-flop circuit 28. Their reset input; (R) is connected to the output of the gate circuit 25, and its output Q is connected to the control input of the gate circuit 22 and to a first input of a NUND gate circuit; ·; 34, the output of which is connected to the reset in; an'i (R) of the gate circuit 33.

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The vertical frequency signal W for switching on the introduction of digital data is applied to the second input of the gate circuit 3 ² J and to the reset input (R) of the x4 counter 26, the output of which is connected to further address inputs of the memories 29 and 30.

The vertical frequency signal V is applied to an input of the control circuit 7, which controls the data for transmission at their data input (IN). The control circuit 7 supplies the line and page addresses, the data for Feeding into the memory 30 and the read-pressure control for the relevant inputs (ADD, D and R / W) of the memory 30, the charge pressure control (R / W) for the memory 29 and the control signal sequences for the converter 31 The circuit 7 is also connected to the addresses (ADD) of the memory 29 to instead of the counters 21, 26 and to provide 23 addresses when the memory 29 is in the "WRITE" state.

The output of the memory 30 is connected to the input of a parity generator 32, which in turn is connected to the input of circuit 31. Whose exit is connected to the data input of the memory 29, the output of which is connected to the data input (D) of the flip-flop circuit 33 is connected, at the output of which the low-pass filter 9 in Fig. 2 to be transmitted signal (DS) is available.

A description of the puncture of the circuit now follows after Pig. 3 with reference to Pig. 4 that a number of waveforms appearing at the various points in the circuit according to Pig. 3 are present. The curve "a" shows the timer signal at input 0; curve "b" represents the horizontal frequency signal H; curve "c" is the timer signal at the input (CP) of the counter 21; the curves "d", "e" and "f" the three outputs of the counter 21, beginning

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with the least significant; the curves "-; ¹¹ and" h "the two least and most significant outputs (with the value 1 or 16) of the counter 23; the curves" i "," 1 "and" m "the reset input (R) , the control input (S) and the output (Q) of the flip-flop circuit 28 and finally the curves "n" and "o" the bit and byte counting. During the active picture interval (signal V), the control circuit 7, which consists of a sub Using known methods, programmed microprocessor can consist of Einsehaltsignale and addresses for transferring the data relating to two lines of text, which are contained in the data memory 30, which can contain up to 100 pages of 24 lines and 40 characters, in the buffer memory 29 "Because it This is a serial memory (1K χ i) (to accommodate 4 lines of 45 8-bit characters), the 7-parallel-bit data coming from the database 30, to which an eighth parity bit is added by the parity generator 32 vrird, surrounded in series by circuit 31 e, which receives 3 address bits (the least significant) that are common to memory 29.

The control circuit 7 also supplies the circuit 31 directly with service data to be introduced at the beginning of each line are, for example, as the start code and the line and page addresses, including security bits, using the Hamming code.

If necessary, the control circuit 7 can also send foreign data (from a serial data transmission terminal for example), in which case it changes the contents of the relative database pages. The data transfer cycle from memory 30 to 31 is repeated for each image until all pages in memory have been transferred and then the cycle begins again.

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The memory therefore contains 29 during each frame reversal all data (text and service) relative to two lines of text for home broadcast during four lines of television.

This is done by the line frequency (line blanking?) Signal H caused that the counters 21 and 23 triggers at the beginning of the active line period. The bit counter 21 starts then with the leading edge of the first timer signal, that he receives to advance (curves "b", "c" and "d" in Fig. 4), while the counter 23 every 8 bits advances to keep a count of bytes. The function of the gate circuit 27 is to wait

ο the number
that the counter reaches / 25, and thereupon it switches off the timers at the inputs of the counter 21 (curves "a ^u and" c "in Fig. 4) in order to stop the counting and to switch the flip-flop circuit 28. The function the gate circuit 25 consists in determining the count 4 on the counter 21 (curve "i" in Fig. 4), which is the moment selected for the start of the transmission, delayed by a minimum of 3 and a maximum of 4 timer periods, depending on the relative 'Zeityeber- and line synchronization phase, which can change over time because the timer frequency is not a whole multiple of the line frequency "

The output Q of the flip-flop circuit supplies in each line 28 is the exact interval in which to insert the data corresponding to 25 χ 8 timer periods. the Function of the inverter 24 and the gate circuit 22 exists therein to delay the bit and byte counts by four timer periods au, i.e. the memory 29 with the address 0 ... Ü to be supplied at the moment when the data is entered begins. The x4 counter 26 ,. which is set to zero by the frame rate signal ¥ and each line

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Moving on, completes the addresses of the memory 29, which supplies an output pulse sequence corresponding to four lines of transmission. The flip-flop circuit 33 serves as a test squaring circuit which tests the output of the memory 29 at a timer frequency and with an appropriate phase (delay T) in order to provide a synchronous switching output signal which is unaffected by response delays in the memory. This flip-flop circuit 33 is ^{disabled by the gate circuit 3 1} J at the end of each set of data and is kept off until the next set begins.

In Fig. 5, the intermediate frequency amplifier 50 of the television signal receiver is connected to a video detector circuit 51, the output of which is connected to a video amplifier 52 and a sound processing and amplifier stage 8 * 1. Its output is connected to a loudspeaker 85, the bandpass filter 53> the synchronous regeneration ^{circuit 5 1} J and the correction circuit 60. The output of the filter 53 is connected to a chrominance signal amplifier 55, which feeds a subcarrier regeneration circuit and a demodulator 56. This receives the output signal of the regeneration circuit 57 at an auxiliary carrier input and supplies two color difference output signals (RY) and (BY), which are applied to two inputs of a matrix 58. The third input of the demodulator 56 is connected to the output of the amplifier 52, which supplies three output signals to the first three inputs of the switch 59.

The output of the correction circuit 60 is connected to an input (IN) of a series-parallel (1 to 8) converter 61 whose output is connected to a blocking stage 62 and to a keyword detector 63. The 8-bit output the locking stage 62 is provided with a parity detector 69, a decoder 81, a memory 82 and a control circuit 76 connected.

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The output of the keyword detector 63 is connected to a switch-on input (OE) of the blocking stage 62, a first input of a switch 65, a first input of an OR gate circuit and the reset input (R) of an x8 counter 64. This is with an input (CP) with the output of the regeneration circuit 57 and with a first output with the timer input (CP) of the blocking stage 62 and a first input of a further switch 66 and with a second output connected to a second input of the OR gate circuit 70. The second input and the control input of switch 65 are each connected to the two outputs (H) and (V) of the regeneration circuit 5 ^, while the output is connected to the reset input (R) of a x4 counter 72 is connected. This is separated with its two outputs with two inputs the control circuit 76, the decoder 81 and the NAND gate circuit 73 connected. The output of the latter is connected to a first input of the OR gate circuit 74 and to a connected to the first input of the AND gate circuit 71, the output of which is connected to the timer input (CP) of the counter 72. The second input and the control input of the switch are each connected to the output of a one-sixth frequency divider 68 and to the output V of the regeneration circuit 54 connected, while the output is connected to the second input of the gate circuit 71 and the timer input (CP) of a x20 counter 75 is connected. This is with a first (5 ~ bit) output to the control circuit 76 and to the memory 82 and with a second output with the reset input (R) of the keyword detector 63, with the control input (S) of the Flip-flop circuit 80 and connected to the second input of the OR gate circuit 74. The reset input (R) is also connected to the output of the gate circuit 74.

The decoder 81 is connected with its output (line address) with the control circuit 76 and with the first address inputs.

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connected to the memory 82. The second address inputs of the latter are connected to the output of the counter 75 and to the control circuit 76, while a Another address input with the output of the flip-flop circuit 80 is connected.

The control circuit .76 is connected with a further output with a first inverter input of the OR gate circuit 78 and via a capacitor 79 with the reset input (11) of the ilipfl op circuit 80, with an output with the control inputs of the switch 59 and there? ¹ amplifier stage 84 connected, with two synchronization inputs connected to the outputs (H) and (V) of the regeneration circuit 54 and connected to one input with the control keyboard 77. The output of the parity detector 69 is connected to the third input of the OR gate circuit; 70 connected. This is with its output with the second input of the OR gate circuit; 78 connected, the output of which is connected to the read-write input; ·; (RW) of the memory 82 is connected.

The output H of the regeneration circuit 54 is also connected to a first Control input of a character generator 83 and a synchronization input of an oscillator 67 connected, the Output with the timer inputs (0P) of the frequency divider 68 and the character generator 85 is connected. The latter also has a second control input connected to the output V of the regeneration circuit 54, with a data input ^ connected to the data output of the memory 82 and with three outputs with three inputs a switch 59 connected. Three color signals R, G and B are available at the output of switch 59 to be routed to the final video amplifiers of the receiver.

The circuit described above works as follows:

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The signal coming from the intermediate frequency amplifier 50 is from the video detector circuit 51 in the form of a complete Video signal detected. From this, the tone signals (84 and 85), the luminance signal Y (52) and the color difference signals (R-Y and B-Y) subtracted in a known manner by a PAL color part - this schematically by the blocks 53, 55, 56 and 57 is shown - as well as the line and frame synchronization signals, which are separated and regenerated by two oscillating circuits in the regeneration circuit 5 ^. The correction circuit 60 is a threshold comparator and clamp circuit for providing a square wave output signal that is digital Corresponds to data contained in the video signal. This pulse sequence is carried out from series in parallel (61) Checking the timer frequency of the transmitted signal Converted according to the invention from the same color subcarrier * Regeneration circuit 57 is regenerated. As soon as the start keyword (lllOOlOO) appears in the converted signal, changes the output of the detector 63 its state to the data acquisition process to start: the sequences of bytes (groups of 8 bits for every 8 timer periods) are locked, switched on by detector 63 and synchronized by byte counter 64, which is also synchronized by detector is switched on. For normal television pictures, the control circuit 76 sets the switch 59 to the outputs R, G and B with to connect the outputs of the matrix 58, which corresponds to the normal operation of the television receiver.

In order to receive the digital data contained in the video signal for a page display on the screen, must a key on the keyboard 77 must be pressed and the number of the selected sheet must be set by the control circuit 76 is saved. This has the effect of switching the switch 59 so that those coming from the character generator 83 Data to the output will happen and the amplifier stage 84 will be switched off.

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The switches 65 and 66 are shown wired ₃ during the emergency run-out period that when there is data to be decoded, the byte sequence signal coming from counter 64 is passed to counters 72 and 75 which are through which Gate circuits 71, 73 and 74 prepared accordingly, counting the first four and the subsequent 20 bytes. The counter 72 supplies the addresses to switch the decoder in 8l i ^ unction so that the row addresses are subtracted from the data sequence and these are decoded (binary number you 0 to 23), as well as the

76
Control circuit to extract the page addresses, to compare them with the digit set on the keyboard JJ and, if they match, to give consent to the input of the data in the memory 82 through the gate circuit 70. V / eg the position of the gates. and Yo, the entry is made during the precise period of time specified by the key word detector 63 (equivalent to 24 characters after the end of the start signal), and zv / ar at the time set by the counter 64 when the data is stable, provided that the parity detector classifies the data as riclrci / ·:. The addresses required by the memory are supplied by the counter 75 (character number from 0 to 19 for a specific transmission line), also by the ilipi'lop circuit 80, which indicates that the first or second half line of text is received, and the decoder 81, which receives the Indicates the number of text wires.

In order for this to happen, the control circuit 76 switches the flip-flop circuit 80 to zero ;; e- "in the transmission lines in which the page addresses are present, and to the following line (output of the counter 75). IJit the end of the field The blanking period has stored two lines of text in memory 82 and is automatically preparing to display them on the image .

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send. The display ^ eschv / indi / Uceit is controlled by the oscillator 67; In this case (40 5-bit characters plus one interval bit), if a display number is required which covers 40 of the 52 usec available, a frequency of 6 MHz must be used. The character speed is controlled by the one-sixth frequency divider 68, the output of which is fed to the counters 72 and 75, insofar as the switches 65 and 66 have switched. The control circuit 76 'switches the switch 59 and supplies the i'ejctzeilenadressen directly to the memory 82 and a _{itückstellöi-:;} nal circuit for flip-flop 80 at the beginning of each scan line, while the character counter 75, the four characters (counter 72) after the start the line scan begins to count (reset signal II of the counter 72), the memory 82 r, iit character addresses from 0 to 19 is supplied, the flip £ - flop circuit 80 toggles and when reset by the i'orschalturr ·; 74 again from 0 to 19. The memory 82, which is set for reading by the gate circuits 70 and 78, supplies the character generator 83 with a data sequence (7 parallel bits in ISO-7 code) as equivalent to a full text page, starting with the first character on the first line.

82

The character generator 83 decodes those received from memory / Data, identifies the control signals and converts the received data into pulse sequences to create characters corresponding to a matrix of 5x7 points, or graphical representations in six colors plus white, according to the control signals on a color television screen. The oscillator 67, which controls the display speed. "- lceit controls is synchronized to exact vertical character alignment right at the beginning of each line (signal H).

The advantages of the invention are clear from the description evident.

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809846/0888

so

In particular, the waiting time is reduced in that the page address transmits every half data transfer; un _; ^; ; line is introduced, which also offers the possibility of changing the order in which the lines are transmitted.

'Ks can be made in the system described a Keihe changes. For example, it is possible to transmit 28 instead of 25 characters per line and to introduce the five service characters on other lines, so that 51 'text characters are obtained per line.

The time overfrequency may differ from the frequency of the auxiliary frequency differentiate according to a multiple of the line frequencies: s. In this case the timer regenerator im i'impfänr; he have an additional oscillator that is also phase-synchronized by the burst.

In Ji ¹ Ig. 5 is an embodiment of a game of a pawn. If the expensive circuit 76 consists of a suitably programmed Wikroprocessor, it can be expedient to use this for performing punctures, which in the exemplary embodiment shown are carried out by separate circuits.

809846/0886

Claims (1)

COHAUSZ & FLORACK PATENT AGENCY OFFICE SCHUMANNSTR. 97. D-4OOO DÜSSELDORF 2.0 Zi) IOU Telephone: (0211) 68334 (5 Telex: 08586513 cop d PATENT LAWYERS:
Dipl.-Ing. W. COHAUSZ Dipl.-Ing. R. KNAUF · Dr.-Ing., Dipl.-Wirtsch.-Ing. A. GERBER · DipL-lng. HB COHAUSZ IHl) ESIi ¹ INDUSTHIA ELETTRODOMESTIC 1'.DALIANA SpA Str.Piossasco Km 17
I-Rivalta, Turin 8th . May 1978 Expectations in particular teletext data, system for transmitting additional data / between a series of television lines within the field blanking period a PAL or SECAM color television signal, characterized in that the additional data on pages of scriptural text or refer to graphical representations and in the form of digital pulse sequences with a certain timer frequency The control and synchronization data are provided in combination with additional pulse sequences and that the selected timer frequency is equal to or equal to the frequency of a color subcarrier the color subcarrier plus or minus a multiple is the line frequency. 2. System according to claim 1, characterized in that in the case of a black-and-white broadcast an oscillation chain at the beginning of each line with the frequency of the color subcarrier and with one constant phase is transmitted in each line. Wa / Ti - 2 - 809846/0886 _{ORIGINAL INSPECTED} ■ J 3. PAL television receiver, which draws u r c η g e k e η η that means are provided for decoding additional digital signals, the data in bezuir on pages ScIu Lfttexteo or graphic representations included in the signal that occurs during the field blanking period is received, this being a time overfrequency that are equal to the frequency of the color subcarrier or the frequency of the color subcarrier plus or minus a multiple of the line frequency and that means are provided for making the additional data visible obtained by decoding the additional digital signals. 4. üupfän; it according to claim 3, characterized that the means comprises a single circuit for regenerating both the frequency of the F; rbhilfsträ.; ers as well as the timer frequency, which remains in function even if the burst is not is alternating, and that a Färbaustastkreis is provided that disables the color channel if the burst is not alternating. 5 · Si) GAl'i television receiver, characterized that means are provided for decoding additional digital signals relating to the data on pages of written text or graphic representations in the Si.mal included during the field blanking period received at a timing frequency equal to the frequency of the color subcarrier or the frequency of the color subcarrier plus or minus a multiple of the line frequency and that is mean to make the additional data visible, which are provided by decoding the additional digital Signals are obtained. 6. Receiver according to claim 5, characterized in that 809846/0886 indicates that a timer regenerator is provided with the frequency of the subcarrier or operates at the frequency of the subcarrier plus or minus a multiple of the line frequency. 7. Encoder for introducing additional data relating to pages of written text and / or graphic representations, which are in digital pulse sequences with a certain Timer frequency are coded into a color television signal a PAL system, characterized that means for encoding the additional data in digital pulse sequences with a Timing frequencies are provided that are equal to the frequency of the color subcarrier or the frequency of the subcarrier plus or minus a multiple of the line frequency. 8. Encoder for introducing additional data relating to pages of written text and / or graphic representations, which are encoded in digital pulse sequences with a certain clock frequency into a color television signal of a SECM system, characterized in that that means for encoding the additional data in digital pulse sequences with a Timing frequencies are provided that are equal to the frequency of the color subcarrier or the frequency of the subcarrier plus or minus a multiple of the cell frequency. 9. System according to claim 1, characterized that the signal with respect to each line of the pages of text is written over two adjacent TV lines is transmitted and that at least one of the control signals is introduced into every first transmission line and omitted from every other transmission line will. 809846/0886 10. System according to claim 9, characterized in that only every other line is omitted Control signals reflect the page number of the referenced data. 11. System according to claim 10, characterized that no control signals are transmitted every second line, 12. System according to claim 9 and 10, characterized that only the picture code control signal is transmitted every other line. 13. System according to one of claims 1 and 9 to 12, characterized in that no sync signals are transmitted during active image scanning. 14. System according to one of claims 1 and 9 to 13, characterized in that the control signals, which are omitted are replaced by data characters. 15. System according to any one of claims 1 and 9 to 14, characterized in that the television signal is a PAL Parb signal. 16. System according to claim 15, characterized that the timer frequency is 4.43361875 MHz and that the sync signal is represented by the burst is. 17. P AL-i'ernsehemp receiver with means for decoding additional digital signals containing data relating to pages of text or graphics and are present in the signal that - 5 809846/0886 Sampling period is received, the timer frequency being equal to the color subcarrier frequency or the frequency of the Subcarrier plus or minus a multiple of the line frequency is, and with means for making the through Decoding of the additional digital signals obtained additional data, characterized in that that the timing signal regenerator consists of an oscillator which is phase locked by the burst will. 18. Receiver according to claim 17, characterized that the timer regenerator is the same color subcarrier regenerator. 19. Receiver according to claim 17 and 18, characterized characterized in that means for series-to-parallel conversion of the additional digital signals are provided which are synchronized by the timer regenerator will. 20. Receiver according to claim 17 to 19, characterized in that the timer signal controlled counting means are provided for providing the number corresponding to the position of each received character in corresponds to the scan line. 21. Receiver according to claim 17 to 20, characterized characterized in that a second oscillator circuit to control the width of the reproduced characters. 22. Receiver according to claim 20 and 21, characterized in that a first set of switching means for connecting the counting means to the timer regenerator or with the second oscillator circuit during the 809846/0886 Data reception or during the data display is provided. 23. Receiver according to claim 17 to 22, characterized in that the display means for the additional data a color and luminance video signal matrix circle, a character generator and a second Set of switching means for transmitting the signals from the first or have second circle to the picture tube. 24 · Receiver according to claim 25, characterized that a control keyboard. is provided, which is connected to a control circuit which also acts on the second set of switching means. 25. Encoder for a system according to claim 15, characterized in that it has a Timer! J-nal-u-enerator circuit that is in phase is synchronized by the color video signal burst. 26. Encoder according to claim 25, characterized in that it has adding means, that of the video signal in the absence of a burst in the video signal add a number of timer signal oscillations during the line retrace times. 27. Encoder according to claim 25 and 26, characterized by a memory circuit that stores data relating to two lines of text during the active Frame period is filled and emptied during four line scan periods in the field blanking period. 28. Encoder according to claim 27, characterized by one controlled by the timer generator Test circuit that is switched on in the path of the output signal from the storage circuit. - 7 -809846/0886