DE2025986A1 - Method and device for checking responses in television broadcasts, in particular for teaching purposes - Google Patents

Description

Method and device for checking the answers to television broadcasts, especially for teaching purposes when conveying knowledge with the help of technical Media, especially in programmed learning, must give the student the opportunity be given to control the accuracy of his answers to questions that are built into the teaching program. For this purpose, in addition to the VJissensstoff and also gives the student the correct answers to the built-in questions will. Appropriately, however, the answers are not transmitted in clear text in order to to avoid influencing the student and to enable control.

For example, it is known to provide instructional programs on tapes save, which also helps to project slides during playback control of signals recorded on a particular track of the tape. the correct answers to questions built into the curriculum are either on contain another track of the tape or the control track for the projection, but are not made known to the student. Only when the school has an answer there is a comparison to determine whether the answer is correct or incorrect was and a corresponding display was given.

The invention has set itself the task of such a response control also for the television transmission of programs, in particular for teaching purposes. It is under Television broadcast is not just a wireless broadcast from a transmitter to one or more receivers, but also a cable transmission and the direct playback of video signals, for example magnetically recorded Understood.

The solution to the problem according to the invention is characterized in that that the picture and sound information including the associated questions about the respective television standard are transmitted that in at least one line, preferably a test cell of the television picture a response signal representing the correct answer is transmitted encoded in the form of pulses that on the receiving side the transmitted Response signal is compared with a response signal generated on the receiving side and that if the two response signals agree or do not agree a correct or incorrect indication is given at the receiving end.

This will meet the following key requirements for the Response Control overall fulfilled in an expedient manner The response signal can be immediate during or can be transferred according to the question.

The transmission of the response signal takes place within the normal TV signal without interference with the respective TV standard.

The response signal can be used together with the image and sound signal common such as magnetic recording devices recorded will.

The reception of the television picture and sound signals is made possible by the response signal not complicated.

There are no significant changes to a normal television receiver necessary. Only a connection had to be provided for extracting the video signals from which the response signal is recovered on the receiving end. Such a connection is at a number of receivers for recording television programs already available or in any case can easily be retrofitted.

The transmission of the response signal according to the invention is unconditional compatible with the transmission of normal television signals. In other words, the answer signals do not interfere with a recipient who is not equipped to receive them, and other taxes A receiver equipped to receive the response signals can easily do so Play normal television programs that do not contain an official entrance signal.

These advantages of the method according to the invention are for example not fulfilled, or at least not fulfilled in its entirety, if one wanted to try transmit the response signals along with the television sound. Then there had to be a certain one Frequency range can be reserved for this, which is lost for normal sound transmission. In addition, appropriate filters or switches would be required in the receiver cannot easily be retrofitted. Then there is also the important one Demand for unconditional compatibility with the transmission of normal television signals not fulfilled. For example, the tone-sequentially transmitted response signals would in one not with corresponding Switch equipped television receivers leading to malfunctions in the inventive transmission of the AniDrtsignale in a line at the edge of the normal picture, on the other hand, does not cause any interference. The test lines to be used, which are also used in a known manner for transmission other information is usually not available to the viewer visible.

There are several options for coding the response signal. According to a further development of the invention, however, it is recommended that the response signal binary-coded in a response area divided into pulse intervals by talc pulses the 'selected line is transferred. Then let sicll do the necessary coding and Make decoding devices particularly simple and enable the clock pulses a simple identification of the respective code pulse.

The invention recommends in its further development that the clock pulses have a gap of 4 microseconds and that the first clock pulse in a Distance equal to an integer multiple, preferably four times, of 4 microseconds occurs after the leading edge of the line sync pulse of the selected line. the Derivation of the clock pulses and the code pulses including their time relationship to each other and to the line synchronization pulses is then particularly simple. This is especially true if following a further recommendation the The width of the clock pulses is about 0.2 microseconds and the width of the response signal pulses is about 1 microsecond, and also the leading edge of the response signal pulses a distance of about 2 microseconds from the previous clock pulse Has.

A check bit is expediently transmitted in the first pulse interval, in order to be able to recognize incorrect response signals.

For the comparison at the receiving end between the transmitted response signal and the locally generated response signal recommends the invention in its further Embodiment that the coded transmitted response answer is first decoded and only then does the comparison take place. This makes the comparison easier, especially when the coded transmitted response signal is decoded so that in Depending on the content of the response signal at one of n outputs, a direct current signal that is used for the comparison.

In this connection it should be noted that the decoded response signal can be fed to several participants for the purpose of comparison. bs exists also the possibility of processing the decoded response signal through another process supply known binrichtubes.

For processing at the receiving end see a further development of the Invention that the serially arriving binary code of the response signal in a register is written and that respectively at the end of the selected line of the Register contents are transferred in parallel to a second register to which the response signal can be taken for comparison. This not only makes processing easy of the response signal allows, but it can also use the response signal after termination its transmission can be stored for a desired period of time.

An arrangement according to the invention for carrying out the circuit The method is characterized in a further dependent claim.

The invention is described in more detail below with reference to the drawings. 1 shows the structure of a television line for receiving a coded response signal; Fig. 2 shows a pulse interval of the television line of Fig. 1; 3 schematically examples for binary-coded response signals in the pulse intervals of a television line; Fig. 4 and 5 show the main components of an embodiment of a transmission-side device for generating a binary coded response signal for mixing in a television line; Figure 6 is a timing diagram for the device of Figures 4 and 5; Figures 7, 8 and 9 the main components of an embodiment of the receiving-side device to recover the response information from the generation according to Fig. 1s and 5, binary coded response signals.

In Fig. 1 the basic structure of a television line is shown, in which the coded response signal is transmitted.

In the following, a binary one is used for the exemplary embodiment described Coding required. 1 First of all, however, we should consider the appropriate selection of the ones to be used TV line said the following. There is basically the possibility of each to select any line of the television picture. A line showing binary pulses would, however, interfere in the visible part of the picture. So Nan appropriately chooses one the so-called test lines at the edge of the picture, which are also used in other contexts for transmission Additional information, for example the black reference standard level, is used will. For the CCIR standard are currently lines 16 to 21 (first field) and 329 to 334 (second picture) agreed, but should also under certain circumstances further lines can be reserved as check lines. In the absence of an international Standardization for the use of the test lines, for example also for the transmission of codes that indicate the origin and route of a shipment appears - without this being associated with any restriction - at the moment line 16 (first Field) for the transmission of the coded response signals. For other television standards appropriate considerations apply.

The line shown in Fig. 1 relates to the CCIR standard 625 lines, a frame rate of 25 Hz, a line rate of 15625 Hz and a line duration of 64 microseconds.

There are no major modifications to the American FCC standard necessary, there at 525 lines and a frame rate of 30 Hz and a line frequency of 15,750 Hz the line duration of 63.5 microseconds is only slightly different from the line duration deviates from the CCIR standard. In contrast, the French standard has 819 lines as well as the old English standard with 405 lines and a line duration of 40.5 microseconds or 98.7 microseconds, appropriate adjustments are required.

The times given in Fig. 1 relate to the leading edge (half height) of the line sync pulse at the beginning of the line. This point in time will Called T0. For the transmission of the binary-coded response signal pulses, a Replybeem provided between 16 microseconds and 60 microseconds after T0 lies. The response area is through clock pulses (clock pulses) in 11 pulse intervals divided. Each interval picks up one of the response signal pulses. The location of the first clock pulse and thus the beginning of the response range is given by the following Considerations determined. For the CCIR-IJorm the width of the line sync pulse is a maximum of 4.9 microseconds in connection with a blanking interval of a maximum of 12.3 Miroseconds. If one continues to assume a response storage register that consists of a number of memory cells that are charged one after the other, but can be discharged in parallel, with each memory cell having an interval of the row is assigned in which it can be loaded, and if one continues to assume that a width of 4 microseconds for each time interval is favorable, so is the first clock pulse of the response area -zweü-kinäig 16 Microseconds after T0 as 12.3 microseconds are reserved for blanking and 16 microseconds is the next higher integer multiple of 4 microseconds is. Such an agreement is based on a binary reduction mechanism, during the da, s jumping of a flip-flop of a Fl # Elop chain controlled serially at 1 MHz the beginning of the answer area defined and the tilting of another, lower value Flip-flops signaled the response intervals.

The line is accordingly every 4 microsecond wide intervals disassembled, of which the first four remain empty. Then begins 16 microseconds after T0, the response range with the first interval. 60 microseconds after T0 is the Answer area ended with a total of 11 intervals. The last interval of 4 Nikroseconds remains empty, and after 64 microseconds the flip-flop chain controlled in this way flips back to their original position. At the same time the next line begins.

The coded response signal pulses correspond to a so-called white level control, i.e. * the test line, which is normally controlled at the black level, is Pulses controlled to white The shape of the response signal pulses and the clock pulses with their temporal values and tolerances is shown in more detail in FIG. 2, where a single pulse interval with a length of 4 microseconds according to tig. 1 shown is. It should also be mentioned that the clock pulses have a rise and fall time of 0.2 microseconds each and a half-width of 0.2 as well Microseconds as so-called 2T pulses with the test pulse for the upper limit frequency after the CCIR standard are identical.

As shown in Figure 1, the first interval contains the response range a check bit, with the help of which the security in the detection of a correct transmission is increased significantly.

With external time allocation, i.e. time allocation controlled by the transmitter via the clock pulses the decoding in the receiver, this check bit is also a check for the correct Transmission of the clock signals, because if the clock signal is faulty or if the clock signal is out of order Internal clock rate guessed # the check bit is not saved as an information bit will.

In the lines of FIG. 3 are some examples of binary-coded response signals shown in the pulse intervals of a test line. Located in the first interval a check bit each time. Because of the binary coding there are for example the second line a response code with the numerical value 1 and the last line a Response code with the numerical value 17 again0 In the first line there is a so-called A zero response therefore represents a response that has no information other than the check # bit contains.

The type of response coding described @ enables transmission a multitude of different answers with high redundancy. Overall are due of the 11 available intervals 211 = 2048 different answers possible. Because of the Transmission of the check bit in the first interval is only half of these answer options available. If it is established that, in addition, the zero response is only used as a cancellation signal, so is obtained you finally get 1023 different answer combinations.

4 and 5 are the main components of an embodiment for the transmission-side devices for generating a binary-coded response signal shown, dßs with the help of a known line shuffler in the selected line of the television picture is mixed in. For the sake of simplicity, the one shown Embodiment according to the table in Fig. 5 only three different answers B, C, D provided.

The first three pulse intervals with the code values are sufficient for this, 1, 2 and 4. An additional "answer" A only occupies the first interval with one Pulse. This corresponds to the check bit.

In Fig.} The three pulse intervals are based on their code values 1, 2, 4 referred to as Code 1, Code 2 and Code 4, respectively. The code voltage, which is called DC voltage of 5 volts is supplied, indicates the yes value "L".

For a more detailed explanation, reference should first be made to the one shown in FIG. 4 Circuit arrangement received. From a goal impulse from a line mixer (Prufzeilenmischgerät) originates, is with the help of a pulse shaper 1 and a Differentiator 2 generates a trigger signal, the positive rise of which is a monostable Multivibrator 3 controls. Its output signal (reset) is provided by the flip-flops Chain back 4 to 12 existing flip-flops. In addition, the output signal of the monostable multivibrator 3 via an inverter 13 and scans a counting gate 14th for a time of wt60 ns off.

A crystal generator 15 generates a sinusoidal signal of 8 MHz, that after conversion into a square-wave signal with the aid of a pulse shaper 16 as well the counting gate 14 is supplied. A third input to the counting gate 14 comes from the output of flip-flop 12, so that counting gate 14, which acts as a WJD gate is executed during the first 32 microseconds (defined by the output i), the counting pulses obtained from the quartz generator 15 on the flip-flop chain 4 to 12 are given. The flip-flop chain is initially controlled with a in order to generate the Delay due to the blanking to catch up again. For the outputs a to i of the Flip-flops 4 to 12 mean that the unmarked outputs are on in the reset state "L" (yes) drove. To form the 2T clock pulses, the rise in the output b of the flip-flop 5 is integrated in an integrating stage 17, the rise of the signal because of the rectifier contained in the integrating stage, however, not. The differential input of a downstream differential amplifier 18 is a controllable one Direct voltage supplied with such an IS that the pulse length at output 200 ns is. In a subsequent integration stage 19, the rise and fall flaSçe ground in such a way that the 2T clock pulse is created. The integration time constants at the same time ensure a delay of the clock pulse of about 30 ns to compensate the TransServer delay of the flip-flop chain.

The binary-coded response signal is formed in accordance with FIG. 5 with the help of a number of Ut gates to which correctly selected output signals of the Flip-flop chain 4 to 12 are supplied. The correct time allocation can be also follow the timing diagram in FIG. 6, in which the output signals b to i of the flip-flops 5 to 12 are shown.

The higher-level AND gate 20 selects the period from 16 to 32 Microseconds after To off, while the downstream AND gates 21, 22 and 23 during this time for the correct interval. Is due to another Input of the AND gates 21, 22 and 23 the respective code signal in the form of a DC voltage on, the corresponding AND gate is on for a period of 1 microsecond switched through the output. The correct number of clock pulses is determined by a Another UD1 gate 24 is generated, the input of which is next to the clock pulse generated according to FIG suitably selected output signals of the flip-flop chain 4 to 12 are supplied. On the output side an OR gate 25 adds the different and arriving at different times Input signals to the complete response signal, which is then sent to the line mixer for mixing in the corresponding Ze, i1 is supplied.

7, 8 and 9 is an integrated circuit constructed embodiment of the receiving-side devices for recovery of the responses A to D from the binary-coded response signals generated according to FIGS. 4 and 5 shown. 7 shows those components that are used for selection of the correct field from the video signal of the receiver are required.

Ii Fig. 8 the components are shown with the help of the response signal is recovered from the test line of the video signal.

In the components of Fig. 9, which is to be connected to the right of Fig. 8, Finally, responses A to D are generated in the form of direct current signals. If, for example, response B is transmitted, it is only at output b8 a DC signal.

Enable additional direct current signals at connections aO or a9 an indication that there is a question and can be answered or that a The answer has been solved 0 A more detailed description of the function in the Fig.

7, 8 and 9 posture arrangements shown are not given here. However, the punctures can be taken from the corresponding data sheets Derive function @ elements of the integrated circuits shown. Just be briefly explained that initially (FIG. 7) the first or second field is also checked will. A line payment is then only made in the first field to determine the selected Line carried out. A flip-flop chain then controls an AND gate, which is used in the selected- (16th) line opens. In the second part of the circuit (Fig. 8) is first the selected line is blanked for 15-5 microseconds and then with the counting of the Clock pulses started After each clock pulse, a memory location of a register is created opened and at the end of the line the register contents in parallel in a second register transfer.

However, this only happens when using a parity check of the check bit has been successful. From the second register the information is then extracted and (Fig. 9) into the DC response signals A to s D converted. The first register is always at the beginning of the following stop picture turned off. In addition, the counting chains are reset.

When creating a television teaching program, the right one can always be the right one Reply signal at the appropriate point in the program without any difficulty entered into the selected test line that the corresponding code DC signals can be applied to AND gates 21, 22 and 23, for example with the aid of keys. When the program is played back on the receiving side, the student generates as requested by the signal "Fragel" at the output aO (Fig. 9), for example by pressing a corresponding key also a direct current response signal, which is then with the help known devices with the correct answers A-D, (Fig. 9) is compared and to an advertisement "resp.

"wrong" leads. All reception facilities are functional summarized in a small device or student desk connected to the video output of the television receiver is connected.

The coded response signal is usually in the selected one for as long as possible Line indicates how the participant's answer is allowed.

The presence of timing pulses calls for a response on the receiving side on, and in the absence of clock pulses, the buttons on the receiving end switched off, after switching off the coded response signals in the transmitter remains the last response signal given is in the register at the receiving end. It can then, for example with a computer-controlled lesson monitoring - should be queried at any time during the break until the next response request, For example, for teaching reasons, the response signal on the receiving end If registers are deleted, a response signal is given on the sending side, which only contains the check bit in a maximum of two consecutive images.

Claims (9)

Claims 1. Procedure for checking responses to television broadcasts, in particular for teaching purposes, characterized in that the image and sound information including the associated questions about the respective television standard (e.g. CCIR) that in at least one line, preferably an early line of the television picture, a The answer signal representing the correct answer is transmitted in coded form in the form of pulses will that receive the transmitted response signal with an eipfangsneits generated response signal is compared; and that in the event of agreement or disagreement of the two response signals at the receiving end a correct or false indication is given will. 2. The method according to claim 1, characterized in that the response signal binary coded in a response area divided into pulse intervals by clock pulses a selected line is transmitted. 3. The method according to claim 2, characterized in that the clock pulses have an interval of four microseconds s and that the first clock pulse in a distance equal to an integer multiple, preferably four times, from four microseconds after the leading edge of the line sync pulse the selected line occurs. 4. The method according to claim 3, characterized in that the width of the clock pulses about 0.2 'micro seconds and the width of the response signal pulses is about a microsecond and that the leading edge of the response signal pulses a distance of about 2 microseconds from the respective previous clock pulse Has. 5. The method according to any one of claims 2-4, characterized in that that a check bit is transmitted in the first pulse interval. 6. The method according to any one of the preceding claims, characterized that at the receiving end the coded transmitted response signal is decoded and that the comparison takes place after decoding. 7. The method according to claim 6, characterized in that the codes transmitted response signal is decoded at the receiving end in such a way that in dependency the content of the response signal has a direct current signal at one of n outputs, which is used for comparison. 8. The method according to any one of claims 2-7, characterized thereby, that the serially arriving binary code of the response signal is written in a register and that at the end of the selected line the register content is parallel in a second register is transferred from which the response signal for the comparison can be found is. 9. Circuit arrangement for performing the method according to a of the preceding claims, characterized by the following components: sendeseitix a coding device for generating the coded response signal and a device for mixing the coded response signal into the line of the television picture provided at the receiving end a device for selecting the line containing the response signal from the video signal a decoder for obtaining the respective Response representing direct current signal, a preferably button-controlled device for generating a direct current signal representing the participants answer, a Comparison device for the two direct current signals and a display device for the result of the comparison.