CN2098132U - Graph and characters tv signal receiving circuit - Google Patents

Abstract

The utility model relates to a graph and character TV signal receiving circuit belonging to an interface circuit which uses a computer for reception and processing of graph and character TV signals. The utility model makes point-to-face data transmission of graph and character TVs even more practical. The utility model is mainly composed of a video signal processor, a data processor, a buffer, a windowing circuit, a bus multiplexer, and an address decoder, wherein, the buffer can use a first-in-first-out buffer, and the bus multiplexer can be replaced by a CPU.

Description

Graph and characters TV signal receiving circuit

The utility model relates to the reception of figure message TV signal, specifically relates to a kind of interface circuit that the calculation machine of using tricks received and handled the teletext signal.

Existing data communication needs special channel, and investment is big.When especially needing multiple spot to receive, acceptance point is many more, invests big more (being directly proportional).This is restricted coverage rate.Except big capacity microwave (or optical fiber) main line, a large amount of at present wired telephone line or wireless speech channels of using, though their coverage rates are bigger, channel capacity is little, speed is low.

So-called teletext (Teletext) is meant the data-signal multiplex (MUX) is inserted in the field flyback of broadcast television signal, utilize the technology of existing television channel, also be TV Field Backward Data Broadcasting (VBI Data Broadcasting) technology for the user data information service.Such teletext data can be used for providing hundreds of pages " videozine " to select to watch (needing installation diagram teletext decoder in user's television receiver) common being seen teletext broadcasting that Here it is at video screen to vast televiewer.Another important use of teletext data is to provide by the passage of point to the face data information for information departments.Because the television broadcasting coverage is big, message pick-up unit is as long as in normal television service area, utilize common antenna (CATV), exterior aerial, satellite earth antenna or utilize domestic aerial in the area preferably at condition of acceptance just can receive teletext data.

The purpose of this utility model will provide a kind of figure message TV signal receiving card exactly, the user is as long as will link to each other with computer in the expansion slot of its insertion computer or by an interface circuit, under the support of computer software, just can receive information and the processing of carrying out multiple form and demonstration that information centre sends by TV station.

According to figure message TV signal receiving card of the present utility model, it is mainly by video signal preprocessor, data processor, buffer, " windowing " circuit, and bus multiplexer and address decoder are formed.Video processor dateout and clock signal are given the data processing circuit device.On the other hand, composite synchronizing signal is delivered to " windowing " circuit.The circuit of " windowing " produces the control end that " window " signal is delivered to data processor (2).The data that data processor will have been handled temporarily deposit buffer in, call in order to computer.Data processor passes through bus multiplexer, is connected with the bus of computer with control line and address wire with data wire.

According to above-mentioned figure message TV signal receiving card, said fifo buffer is a memory chip.

According to above-mentioned figure message TV signal receiving card, said bus multiplexer can replace with a CPU (CPU).

Below in conjunction with accompanying drawing concrete enforcement of the present utility model is elaborated.

Figure one is the schematic diagram of explanation the utility model figure message TV signal receiving card use occasion.

Figure two is circuit theory diagrams of first kind of structure of the utility model figure message TV signal receiving card.

Figure three is circuit theory diagrams of second kind of structure of the utility model figure message TV signal receiving card.

Figure four is line maps of " windowing " circuit in the utility model figure message TV signal receiving card.

Figure five is the corresponding program flow chart of the computer that links to each other with the utility model figure message TV signal receiving card, i.e. figure message TV signal receiving card computer interface program flow diagram.

At first referring to figure (), it shows the use occasion of the utility model figure message TV signal receiving card.Figure message TV signal sends from zone center and passes through television transmitter, or microwave transmitter is sent to corresponding receiving terminal through hyperfrequency or microwave transmission, or directly be sent to corresponding receiving terminal by camera cable, receiving terminal draws vision signal through the demodulation of demodulator, this vision signal can be delivered to figure message TV signal receiving card described in the utility model, this receiving card is under computer software is supported, figure message TV signal is separated from composite video signal, and teletext data delivered in the computer process and display.

Figure (two) shows the circuit theory diagrams of first kind of embodiment of the utility model figure message TV signal receiving card.It mainly comprises video signal preprocessor (1), data processor (2), buffer (3), " windowing " circuit (4), bus multiplexer (5), address decoder (6) etc.Directly be added to video signal preprocessor (1) from the vision signal of demodulator output, this processor can be a ready-made integrated circuit block, for example: SAA5231 video signal preprocessor (1), after from video input signals, taking out data-signal and recovered clock signal on the one hand, give data processor (2) in the lump, this data processing circuit (2) also can be a ready-made integrated circuit block, for example: SAA5250.On the other hand, video signal preprocessor is isolated composite synchronizing signal and is added on " windowing " circuit (4) (seeing Fig. 4 and explanation thereof for details) from composite video signal.The circuit of " windowing " produces a window signal, field flyback pulse signal for example, and the control end VAL(video input that it is delivered to data processor (2) is effectively) on, to guarantee that data processor is not subjected to the interference of this window with external signal.Data processor (2) is handled the data of receiving according to computer commands, and the result that will handle writes (buffer can be the buffer of a first-in first-out) in the buffer (3).Computer will constantly search the status word of data processor (2) by address decoder, and from the readout register of data processor one group of data will be taken out and is stored in the internal memory of computer in due course.Bus multiplexer links to each other with the bus (9) of computer with control line (7) and address wire (8) by data wire.Its sends adopt the data and the address timesharing ground that come from computer into data processor (2), or data of coming and address timesharing from data processor (2) send into computer.

Figure (three) shows the circuit theory diagrams of second kind of embodiment of the utility model figure message TV signal receiving card.With figure (two) unique different be that a CPU (CPU) (10) has replaced the bus multiplexer (5) among the figure (two), other circuit all is identical, and represents with identical label.The advantage of this circuit is the burden that has alleviated computer, makes computer processing speed faster, and disposal ability is stronger.

Figure (four) has showed figure (two), a kind of concrete line map of " windowing " circuit (4) among the figure (three), in this example, " window " signal is such as being the field flyback pulse signal, in this circuit, the composite synchronizing signal of sending here from video input processor is at first through reverser U8E(74LS04) be divided into three the tunnel after oppositely, the first via is sent monostable flipflop U5A(MC14013) the generation line synchronizing signal, the second the tunnel send flip and flop generator U5B(MC14013) the generation field sync signal, this signal is again through monostable multivibrator U6A(74LS221) one of generation and the corresponding signal of windowing of field synchronization, its width of windowing is by R9 and C19 decision, the signal of windowing is delivered to NOT-AND gate U7A(74LS00) an input, Third Road is delivered to NOT-AND gate U7A(74LS00) another input.Export needed window signal at last and give data processing circuit.

Figure (five) also shows the corresponding program flow chart of computer, i.e. figure message TV signal receiving card computer interface program flow diagram.In this program, at first the data processor is carried out initialization; Log-on data processor then; The 3rd step judged then whether buffer area is filled with; If discontented, then whether judgment data is effective, returns for the 3rd step as invalid then program; If effectively then from buffer, read one group of data by the first-in first-out order, enter the 6th step--data processor then by data processing; If the 3rd step was judged buffer area and is full then the buffer area total data is read; Whether judgment data is correct again, removes buffer then; If incorrect, then program return for second step; If correct, then enter the 6th step--data processor; The data that to handle deposit the user cache district at last, in order to showing the usefulness of printing grade.

At length introduced above according to figure message TV signal receiving card of the present utility model, used it, so that teletext data is become a reality by the data transmission of point to face, the method is compared with common data transferring method, has the following advantages:

1, small investment: because this method has been utilized existing television channel, do not need the construction of line.

2, the quantity of acceptance point is unrestricted, and acceptance point is more many, and the benefit of system is just more big.

3, speed is fast: the channel capacity of teletext data is big, and the information content that sends in the unit interval is bigger than most other method. After the normal program of TV station finished, teletext data can be inserted on the arbitrarily available television line (Full Chanuel Data Broadcastind), and speed is faster like this.

4, real-time: teletext data can upgrade the information that sends at any time, and the information that the user receives is generally latest news.

5, the form of transmission information is unrestricted, and system can transmit manuscript, picture, computer software, advertisement, newspaper layout or the like for the user.

Though teletext data is sent to face by point in addition, can carry out the logic addressing to the user according to user's requirement, make some information only give some specific user, also can be according to user's needs to information encryption.

Claims (3)

1, a kind of figure message TV signal receiving card is characterized in that: it mainly by video signal preprocessor (1), data processor (2), buffer (3), window " circuit (4), bus multiplexer (5) and address decoder (6) form; Video processor (1) dateout and clock signal are given data processor (2), on the other hand, composite synchronizing signal are delivered to " windowing " circuit (4) and are produced the control end that " window " signal is delivered to data processor (2); The data that data processor will have been handled temporarily deposit buffer in, call in order to computer; Data processor (2) is connected with the bus of computer with address wire (8) with control line (7) with data wire by bus multiplexer (5).

2,, it is characterized in that said buffer is the buffer of a first-in first-out according to the said figure message TV signal receiving card of claim 1.

3,, it is characterized in that said bus multiplexer can replace with a CPU (CPU) according to the said figure message TV signal receiving card of claim 1.

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