DE4239024A1 - HF modulator for converting recorded video signals to TV signals - adjusts functions of individual components automatically by receiving addressed data from separate transmitter - Google Patents

Abstract

A h.f. modulator, in which each component (e.g. 50,70,100j,120,150,24,23) whose function or output frequency is to be adjusted, can automatically adjust this according to data fed to that component. A transmitter (29) is provided separately from the main body of the modulator. The transmitter (29) transmits data for adjusting the function or output frequency of each component. A receiver (28) is located inside the main body of the modulator. This receives the transmitted data and supplies it to the component corresponding to the address included in the data. ADVANTAGE - Has fewer parts and is simple to control and service. Number of channels can be increased.

Description

The invention relates to an RF modulator for order put one of a video tape for example recorder played composite video signals into a television broadcast signal.

Fig. 2 is a block diagram of a construction of a conventional RF modulator. An input terminal ( 1 ) receives a composite video signal coming from a video tape recorder or the like, which is treated by a clamping circuit ( 2 ) in such a way that its blanking level is set to a specific voltage value. A white level limiter circuit ( 3 ) is used to detect the white level of the composite video signal.

A test signal generator ( 4 ) is used to set up a reception channel. A switch ( 5 ) is used to select the output of the white level limiter ( 3 ) or the output of the test signal generator ( 4 ). A video carrier generator ( 6 ) is used to generate a video carrier wave. A video modulation / sound mixing circuit ( 7 ) mixes a video carrier with a sound difference carrier signal and outputs the mixed signal as an RF signal via a high-pass filter (HPF) ( 8 ) to an output connection ( 9 ).

A bias control circuit ( 10 ) is used to set the video mulmation factor. An input terminal ( 11 ) receives a sound signal. An attenuator ( 12 ) is used to set the tone modulation factor. A pre-emphasis circuit ( 13 ) raises the high-frequency range of the audio signal. A tone FM modulator consists of a difference Os zillator for generating a differential carrier signal and an FM modulator for FM modulation of the differential carrier signal in accordance with the output signal of the pre-emphasis circuit ( 13 ). An attenuator ( 15 ) is used to adjust the ratio between the output levels of the video signal and the sound signal.

Get RF modulators with the structure described in the manufacturing company a number of settings so that they are available as finished products. such settings concern:

• 1) Setting the frequency of the video carriers wave;
• 2) Switching the test signal and the external sig nals;
• 3) setting the video modulation factor;
• 4) setting the FM modulation factor;
• 5) Setting the level ratio video signal / sound signal;
• 6) Setting the sound carrier frequency.

For the RF modulators with the one explained above The following problems occurred during construction:

• 1) Parts had to be changed or the above explained various setting processes had to be in accordance with that television standard made in the country of destination is decisive for the device. To exchange of parts and difficulty adjusting could avoid products for those concerned individual television standards will. But this makes it extensive  Warehousing as well as complex service and Maintenance work in every single transmission offers a certain television standard Lich. The production control becomes complicated graces.
• 2) Since the tone modulation factor within the RF Modulators set in a single way must be so that the RF modulator for each the television reception standards is suitable the circuit complicated and the number of components increases sharply. This will make the product expensive.
• 3) The set values fluctuate Frequency, due to a frequency drift that is due to non-uniform Setting the video frequency and sound carrier.
• 4) In today's RF modulators a ver changeable capacity (for the UHF output) to Use, the changing capacity area is narrowed to the component to keep small. With that, however, the Do not increase the number of possible channels.

The task of the invention is to add an RF modulator create that avoids the above problems det. To this end, the present invention provides a RF modulator in which each component whose Function or output frequency can be set must have the ability, the function or the Output frequency automatically according to Set data that are fed to it. A transmission device is also separated provided by the main body of the RF modulator to  the data for setting the function or the To send output frequency in each element a reception inside the main body direction is formed, which receives the data and they correspond to the destination address of the Delivers data to the corresponding element.

Through the above Design it is possible that the data for each item for setting whose function or output frequency is used be received so that the data and then to the Determination element to be passed on. If the Data is entered into the determination element, can change its function or output frequency According to the data set.

This makes it possible to turn the function on or off frequency from outside the RF modulator adjust.

An embodiment of the Er Finding explained in more detail with reference to the drawing.

Show it:

Fig. 1 is a block diagram showing a configuration of an embodiment of the RF modulator according to the invention;

Fig. 2 is a block diagram of an already designed structure of an RF modulator.

Fig. 1 shows in a block diagram form the construction of an embodiment of an inventive en RF modulator. Fig. 1 contains z. T. elements that are also shown in Fig. 2. These elements have the same reference symbols and are not described again.

The present invention differs from the above-described, already designed RF modulator in that variable frequency dividers 23 and 24 , switches 16 and 50 , a video modulation / sound mixing circuit 70 , a bias control circuit 100 and attenuators 120 and 150 are provided that have the function of performing a specified operation according to data supplied by them. In addition, a receiver 28 is provided which receives data sent to it and feeds it to each of the above-mentioned elements. A transmitter 29 is used to send this data. The receiver 28 is located inside the RF modulator, while the transmitter 29 is located outside of the RF modulator.

The switch 50 selects either the output of the white level limiter 3 or the output of the test signal generator 4 , depending on the data value "Da". After selection, the switch 50 maintains its state until the data "Da" is entered. The video modulation / sound mixing circuit 70 has the same function as the image modulation / sound mixing circuit 7 described above, and it also selects either the positive modulation (in the case of L / SECAM) or the negative modulation (in the case of PAL, G, I, DK, LSECAM) depending on the data value "Db". After selection, the image modulation / sound mixing circuit 70 maintains the state until the next data value "Db" is entered.

The bias control circuit 10 sets the image modulation factor in accordance with the data value "Dc". After the setting, the bias controller 100 maintains its state until the next data value "Dc" is entered. Attenuator 120 sets the tone modulation factor according to the data value "Dd". After adjustment, the attenuator 120 remains in the same state until the next data value "Dd" is entered. The attenuator 150 provides the adjustment of the relationship between the output level of the image signal and the sound signal depending on the data value "De". After the setting, the attenuator remains in its state until the next input of a data value "De".

The switch 16 serves to set either frequency modulation or amplitude modulation, ie it selects one of the types of modulation depending on the data value “Df”. After selection, switch 16 remains in its state until the next data value "Df" is entered.

A reference signal generator 19 , a frequency divider 20 , a phase comparator 21 , a low-pass filter (TPF) 22 , a variable frequency divider 23 and the image carrier generator 6 form a PLL circuit (phase locked loop). In this case, part of the output signal of the image carrier generator 6 is given via the variable frequency divider 23 in the phase comparator 21 in order to be compared with a reference frequency signal which is output by the reference signal generator 19 .

A phase error signal coming from the phase comparator 21 is smoothed in the TPF 22 and supplied as a control voltage, for example to a variable capacitance diode (not shown), which is located in a resonance circuit inside the image carrier generator 6 in the form of a voltage-controlled oscillator (VCO), the oscillations frequency of the image carrier generator 6 is kept constant th.

The frequency division ratio of the variable frequency divider 23 is controlled depending on the station selection. In this case, the frequency before the frequency division, the frequency at the output of the image carrier generator 6 , is controlled so that the output frequency of the variable frequency divider 23 (the input frequency of the phase comparator 21 ) does not change even if the frequency division ratio changes.

A sound carrier FM modulation circuit 18 , the reference signal generator 19 , the frequency divider 20 , the variable frequency divider 24 , a phase comparator 25 and a low-pass filter (TPF) likewise form a PLL circuit of the type described above. The reference frequency generator 19 and the frequency divider 20 are used by both PLL circuits at the same time.

The switches 16 and 50 , the image modulation image / sound mixing circuits 70 , the bias control circuit 100 , the attenuators 120 and the variable frequency dividers 23 and 24 are all connected to a data bus, not shown.

A receiver 28 is used to receive selection data and setting data, and selection and setting data received from it are sent to the data bus and supplied to one of the following components: switches 16 and 50 , image modulation / sound mixing circuit 70 , bias control circuit 100 , attenuators 120 and 150 and variable frequency dividers 23 and 24 . For example, if a set of selection data is received, and if this data is for switch 50 to select the test signal, the data is supplied to switch 50 so that it switches to the side by which the test signal is selected.

A transmitter 29 is used to send selection data and setting data. It sends selection data for the switches 16 and 50 and the image modulation / sound mixing circuit 70 and sends setting data for the bias control circuit 100 , the damping element of the 120 and 150 and the variable frequency parts 23 and 24 . The transmitter 29 is arranged separately from the main body of the RF modulator.

In the RF modulator with the structure described above, selection data and setting data are transmitted by the transmitter 29 in accordance with the respective television standard. For example, if the data value "Dd" is sent, this data value is received by the receiver 28 and passed over the data bus. The selection data "Db" coming from the data bus are input to the picture modulation / sound mixing circuit 70 , where either the positive modulation (L / SECAM) or the negative modulation (PAL, G, I, DK, LSECAM ) is selected.

Similarly, the selection or Setting the elements as objects of Aus choice or setting as follows:

• 1) Selection of the test signal or the external one Video signal through selection data "Da".  
• 2) Adjust the image modulation factor after Providing the data value "Dc".
• 3) Customizing the sound modulation factor the setting data value "Dd".
• 4) Setting the level ratio of Bildsig nal / sound signal according to the setting data "De".
• 5) Selection of amplitude modulation / frequency mod lation according to the selection data "Df".
• 6) Adjust the tone signal frequency as required the setting data "Dg".
• 7) Adjust the image carrier frequency as required the setting data "Dh".

While only the function of setting the output frequency in accordance with the input data for an element such as the variable frequency dividers 23 and 24 is provided in the embodiment described above, such a control function can be provided that changes are not made to an input signal, but a constant Value is maintained. By creating such a control function, adverse influences of frequency drifts can be suppressed, which can be attributed to non-uniform setting of the video frequency and the sound carrier or to temperature changes.

In the RF modulator described above according to the Invention is such a possibility for everyone Element provided which has a function setting the setting of an output frequency or  The like requires, so that an automa table setting of function or output frequency depends on data that is built element are fed. Furthermore, a sen deeinrichtung provided separately from the Main body of the RF modulator is arranged and is used to set the function or data to send the output frequency in each element.

Furthermore, a receiving device is provided which itself inside the main body of the RF modulator and is used to receive data that are sent by the transmitter, and the Data passed to the determination element. Thereby The following advantages can be achieved:

• 1) A multi-function RF modulator can be used realize without complex circuits.
• 2) Because of the ability to customize the features Set the delivery address, don't need specific products for everyone Installation site. In order to the design costs are reduced and maintenance. In addition, the Simplify product control. Changes in leave the design for each site perform easily.
• 3) There is no need to fine by hand make settings so that here too be reduced by production costs can. Productivity is significantly reduced improves.
• 4) There can be a uniform setting the video frequency and the sound carrier will suffice, and consequently no frequency  Drifts out due to uneven setting called. Therefore the set one changes Frequency practically not.
• 5) The number of components can be reduced. To create the UHF output under use a variable capacitor can a capacitor can be used whose Capacity itself to receive all Channels. This is the requirement small component size as well as the requirement multiple channels taken into account.

Claims (1)

RF modulator, in which each component (e.g. 50 , 70, 100, 120, 150, 24, 23 ), whose function or output frequency is to be set, is equipped with the option of performing the function or output frequency as required automatically set data supplied by the device, characterized by a transmitter ( 29 ) which is arranged separately from the main body of the RF modulator to transmit the data for setting the function or the output frequency of each component, and a receiver which is located within the main body of the RF modulator and serves to receive the data and to guide it to the component corresponding to the destination address of the data.