DE1115762B - Receiver for a color television transmission system - Google Patents

Description

GERMAN

PATENT OFFICE

N18243 YUla / lla ¹

REGISTRATION DATE: APRIL 28, 1960

NOTICE
THE REGISTRATION
AND ISSUE OF
EDITORIAL: OCTOBER 26, 1961

The invention relates to a receiver for a color television transmission system in which the transmitted, modulated onto a carrier wave signal a component that is essentially on relates the brightness of a scene, and contains at least one component that comes from a subcarrier wave consists, which is modulated by at least one signal, which relates to the color content of the relevant Scene relates.

In a known system of the type mentioned above, there is the first-mentioned component, the brightness signal, from a combination of three signals, the first of which relates to the green color components the scene, the second on the red color component of this scene and the third on the blue color components this scene relates.

The second component consists of a subcarrier shaft, which is modulated in quadrature with two signals, which are also combinations of the three signals which relate to the green, red and blue color components of the scene, which However, combinations differ from one another and also from the combination of the Brightness signal are different.

Receivers for the system described above work as follows: After detection, it is in the receiver the brightness signal and the subcarrier wave modulated in quadrature are available. By means of one common Process called synchronous detection are made from this modulated subcarrier wave the two combinations different from the brightness signal are derived. From these two combinations and the brightness signal are finally the three to be fed to the reproducing device Color signals derived.

To achieve the two components, one can use the carrier wave modulated by these components, which in practice is mostly returned to the intermediate frequency position to a single detector. The two components can be separated by means of filter networks in the output of this detector will.

It is also known to apply signals modulated onto a carrier wave to two detectors; to the The output of a detector is the first component, which is essentially related to the brightness removed; the output of the other detector becomes the second, from the subcarrier wave with the modulation signals related to the color content are removed.

This use of two detectors is used to create the possibility of detecting the relevant detectors.

Receiver for a color television transmission system

Applicant:

N. V. Philips' Gloeilampenfabrieken, Eindhoven (Netherlands)

Representative: Dipl.-Ing. E. E. Walther, patent attorney, Hamburg 1, Mönckebergstr. 7th

Claimed priority: Netherlands of May 1, 1959 (No. 238 820)

Willem van den Bussche, Eindhoven (Netherlands), has been named as the inventor

gates better to adapt to the component, which of the detector in question from the on a Carrier wave modulated signal must be recovered.

When using two detectors, the signal modulated onto a carrier wave becomes a transformer fed whose secondary winding is coupled to a detector to which the first component is taken, the primary winding being coupled to a detector to which the second Component is removed in order to achieve a better separation of the two components.

It results that harmonics of the intermediate frequency image and sound carrier waves, which in the with The detector coupled to the primary winding of the transformer is generated on the last intermediate frequency amplifier section and through the chassis, through the wiring and also through direct radiation, very interfering signals into the antenna circuit of the recipient.

In order to remedy this disadvantage, it has already been proposed that modulated onto a carrier wave Signal via separate amplifier to two detectors, one of these detectors the first component and the second component is removed from the other of these detectors.

In television receivers in general, with regard to control and / or measurement purposes, the Need to be able to dispose of the image carrier shaft.

It is known to supply the intermediate frequency picture carrier wave to a frequency discriminator, the

109 710 / 22S

3 4

a control voltage is taken, which is fine-tuned. The antenna system 1 is high-tuned of the recipient. frequency stage 2 and a mixer stage 3 coupled. That

It is also known that the intermediate frequency picture output signal of the mixer 3 becomes an intermediate carrier wave to be fed to a separate detector, frequency stage 4 fed.

in which a voltage is generated which serves to 5 The last section of this intermediate frequency stage 4

a mismatch of the receiver to the be is illustrated in detail, similar to the two

to display the appropriate value. detectors 5 and 15 coupled to this stage.

The removal of this picture carrier wave from the Before these individual parts, to which the He-television signal channel requires special precaution-finding, is discussed further, the general assembly and the frequency characteristic of this channel are next to avoid distortion of the amplitude. Discussed in more detail in both of the modes of operation of the receiver,
mentioned cases, the entire intermediate frequency signal modulated by the audio signal can be fed to the frequency of the video carrier wave in the intermediate frequency stage 4 or in a tuned oscillating circuit, which is used as the detectors 5 or 15, the differential carrier such a load on the channel for the television principle is used or not, from the television signal and the signal signals are separated in this channel. In the illustrated component with frequencies in the vicinity of the image guidance example, this separation takes place in the detector attenuates the carrier wave considerably. 15. The sound carrier wave is a two-way frequency

To avoid this attenuation, it is z. B. stage 11 is supplied, which itself with a tone detector

knows, the television signal is coupled to the resonant circuit via 20 12. The output of the detector

feed a separation tube; this measure is carried out via a low-frequency amplifier 13

however, rides an additional cost. or several speakers 14 supplied.

According to the invention, a receiver for the transmitted television signal also contains a color television transmission system in which the necessary synchronization signals for the transmitted, on a carrier wave modulated sawtooth generators for the horizontal and vertical signals a component that is essentially on deflection as well as for the oscillator, which relates to the brightness of a scene, and generates at least synchronous detection voltages, contains a component that consists of a subcarrier The synchronizing signals for horizontal and vertical wave, which is generated by at least one signal modul deflection are in the separating circuit 7 from which is derived, which refers back to the color content of this scene 30 output signal of a video amplifier stage 6, which on a carrier wave which is coupled to the detector 5.
The synchronizing impulses for the vertical detectors are supplied, from which the relevant grain steering are taken from a device 8 for synchronizing components, the image carrier shaft for controlling a single part of the same forming control and / or measuring purposes via an oscillation - 35 sawtooth generator supplied; the output currents are removed from the circuit, which is received in the detector of the device 8, is not shown in the figure, from which the vertical deflection coils of the display tube made up of the modulated auxiliary carrier shaft are removed. fed.

The invention is based on the knowledge that the synchronization pulses for the horizontal Abeine Attenuation of the signal components in the vicinity 40 steering are supplied to the device 9 the image carrier wave in the detector for the second grain synchronizing the one forming part of the same component whose frequency range is in the modulated sawtooth generator; the output currents of the board at a considerable distance from the frequency direction 9 are not shown in the figure either The image carrier wave lies on this second grain-placed horizontal deflection coil of the display component almost no adverse influence 45 tube supplied.

The devices 8 and 9 contain the given of these Attenuation on the input signal of the detection case still required flywheel circuits, and tors for the grain relating to the brightness - it can also be used by the device 9 on beponente, in which this attenuation is well known from the kickback of the line saw could act, practically from 50 tooth generator a DC voltage can be achieved, the is closed thanks to the fact that this can serve as high voltage for the display tube. Signal modulated on intermediate frequency carrier wave The output signal of the video amplifier stage 6 A suppression filter 17 is fed to the two detectors via separate amplifiers. Run will. as is known, the frequency of the subcarrier wave becomes like this

The invention is selected based on the in the drawing 55 that the disruptive effect of the second

given figures, for example, explained in more detail. Signal component to the first signal component

This shows is minimal, but it still emerges as a necessary

Fig. 1 shows an embodiment of a receiver agile in the channel of the first component

according to the invention; Pre-suppression filter for the second component

FIGS. 2 and 3 show individual parts of such a receiver.

The output signal of the video amplifier stage 6

Vibration circuit obtained image carrier wave on hand is also fed to a device 29 in which

two examples is illustrated in more detail. a control voltage for the automatic strength control

In Fig. 1, 1 denotes a suitable antenna which is generated, which control voltage both the system for receiving a carrier wave modulated by the two mentioned intermediate frequency stage 4 and the high frequency components. In addition, level 2 can be added,
A second carrier wave is also received, which in The output signal of the detector 15 is frequency and amplitude modulated by a sound signal on the part of a band filter 16, which only the second grain

5 6

component lets through, apart of course from control grids of two amplifiers connected in parallel tubes 41 and 42 in the frequency range of the second component is supplied. The amplifier tube lying frequencies of the brightness signal, and 41 is via a transformer 44 to the detector 5 on the other hand the audio intermediate frequency stage 11 and the amplifier tube 42 is passed through a Trans. 5 formator 45 coupled to detector 15.

The removal of the differential carrier tone signal from Es will show that it may also the detector for the second component has the advantage of being able to use the output signal of mixer 3 that in the input of the detector for the indirect feed to the separate amplifiers. The elements 46 and 47 of the detector 5 also form part of the brightness signal can be pressed, so that in the output of this De- io the transformer 44 a band filter which is connected to the first tector or no additional component is adapted in the video amplifier; 48, 49 denote one Liches circle which has a disadvantageous effect on the brightness signal and which is used to suppress the sound carrier wave in Suppression filter for this sound carrier wave in front of this detector is used; 50 denotes the detector seen needs to become. diode, and capacitors 51 and 53 and the

The output signal of the band filter 16 is used by a coil 54 to suppress the harmonics

Amplifier 19 supplied, which on the one hand with one of the intermediate frequency signal in the output of the Detek-

Isolating circuit 18 in which the synchronization signals for tors. The video amplifier 6 is via a delay

the synchronous detection from the output signal of the approximately line 52 with the connection point of the coil

Amplifier 19 are recovered, and other 54 and the capacitor 53 are coupled. The delay

on the other hand, with two synchronous detectors 20 and 21, the line 52 serves to reduce the delays in the

is bound. Demodulation products of the modulated in quadrature

The synchronization signals for synchronous detection, lated subcarrier wave at the input of the matrix network

which signals at the output of the isolating circuit 18 are set up 25 to compensate.

occur, are fed to an oscillator 10, to form the elements 55 and 56 of the detector 15

whose output two voltages with the same frequency 25 with the transformer 45 a band filter which is connected to the

sequences occur, the phases of which, however, are adjusted by 90 ° second component; 57 denotes the

are shifted against each other. These two detector diodes of the detector 15, and the condenser

Voltages are used by the synchronous detectors 20 or capacitors 58 and 59 and the coil 60 again

21 supplied. to suppress the harmonics of the intermediate

It is assumed that the output signal of the 30 frequency signal. The connection point of the condenser

Detector 20, the signal with the larger bandwidth sators 59 and the coil 60 is the input signal

(the / signal) and that the output signal for the band filter 16 and the audio intermediate frequency

the signal with the smaller band step 11 is taken from the detector 21,

width (the Q signal). In parallel with the capacitor 56, the

The synchronous detector 20 is furthermore the series connection with an exemplary embodiment placed in subscript

pass filter 22 with a relatively large bandwidth of the capacitor 61 and the circuit 62 switched on,

and the synchronous detector 21 is equipped with a low-pass filter. This circle 62 is based on the

filter 23 with a relatively small bandwidth desired frequency of the image intermediate frequency

tied together. Carrier wave matched.

With regard to the fact that the filter 23 becomes 40 The signal appearing over this circle

a greater delay in going through this filter via the pair of clamps 63, 73 one in this figure

outgoing signal introduces as the filter 22, is fed to the device not shown,

Output of the filter 22 a delay line 28 which this signal for control and / or measurement purposes

recorded using this delay difference,

compensates. 45 The attenuation which this circle in the de-

The output signals of the line 28 and the filter tektor 15 on the signal components in the vicinity of the

23 are fed to a matrix network 23, which exerts image carrier wave, has practically no influence

from these output signals three so-called color components onto the signal components of the second component,

forms differential signals. In addition, this attenuation cannot influence a color difference signal

Signal that counts to the brightness signal exert a signal 50 by reacting on the detector 5 thanks

supplies, which refers to a certain color component of the fact that the two detectors through the

the scene to be played back. Amplifiers 41 and 42 are separated from each other.

The combination with the brightness signal takes place. According to the figure, terminal 73 of circuit 62 is

grounded in the display tube in the example shown. It will be evident that this is not necessary

26 itself. To do this, the output signal of the under 55 is. In Fig. 3 to be discussed below, e.g. B.

pressureless 17, ie the brightness signal, with between terminal 73 and earth, another network

negative polarity is provided for the three interconnected, the result of the parallel connection of a diode

Cathode 30 which is equipped with three electron guns and a resistor,

three-color tube 26 seen. It should be noted that when the transmitted signal

In addition, since the output signals of the matrix 60 would contain more than one component consisting of a modulated subcarrier wave 25 to the three control units not connected to one another, these other components are fed to grids 31, 32 or 33, the component or components are also sent to the detector of the three Electron guns generated electrons could be taken, electron bundles each with the sum of the brightness signal. In FIG. 2, the detector 15 is modulated together with a consumption end of a color difference signal. 65 device of the occurring over the circle 62 with respect to the intermediate frequency stage 4 contains oscillation shown separately. This consumes the penultimate section of an amplifier tube 40, the device here serves as a display device for its output signal via a filter network 43 for the tuning and is known per se.

Corresponding elements of FIGS. 1 and 2 are labeled in the same way.

The signal appearing at the terminals 63 and 73 is detected in the detector 64, which consists of the diode 65, the resistor 66 and the capacitor 67. The DC voltage occurring across the resistor 66 , the magnitude of which is known to be a measure of the tuning, is fed to the amplifier tube 68.

The voltage appearing across the load resistor 69 of this tube 68 is fed to the control grid of the triode part of the display tube 69, the anode 70 of this triode part with the Control element 71 of the display part of the tube 69 is connected, whereby in a known manner from the Change of the luminous surface of the luminescent screen 72 an indicator for the vote of the Recipient is achieved.

In Fig. 3 the detector 15 is shown separately again together with another consumption device, which device in this case for generating a control voltage for automatic frequency control of the local oscillator, which forms part of the mixer 3.

Corresponding elements of FIGS. 1 and 3 are also designated here in the same way.

In the illustrated embodiment, the oscillating circuit 62 'is an individual part of a frequency discriminator. With that in mind, the capacitance of this circuit is in two capacitors 74 and 75 divided, and the television signal is through a coupling capacitor 76 to the connection point of the Capacitors 74 and 75 are supplied. The terminals 63 'and 73' are each connected to a diode 76 or 77, which are bridged by a resistor 78 and 79 respectively. The output voltage of the frequency discriminator across the capacitor 80 is via the network of the resistor 81 and the capacitor 82 is fed to the amplifier tube 83. Via the cathode resistor 84 of this tube, the Receive control voltage. This control voltage is fed to the local oscillator of the mixer 3, and this voltage ensures in a known manner that the local oscillator is always readjusted in such a way that the frequencies of the generated intermediate frequency image and sound carrier waves for the intermediate frequency transmission curve assume the most favorable value.

It can be seen that the oscillation circuit inserted in the detector 15 is not part of the frequency discriminator needs to form. The discriminator can be provided with a separate circle. the Terminal 63 of the oscillating circuit 62 in Fig. 1 can, for. B. directly capacitive or transformer with coupled to the junction of the capacitors 74 and the resonant circuit 62 'of FIG be.

Claims (5)

PATENT CLAIMS: A receiver for a color television transmission system, the transmitted signal modulated onto a carrier wave having a component which essentially relates to the brightness of a scene and further including at least one component which consists of a subcarrier wave which is represented by at least one signal is modulated, which relates to the color content of this scene, the recovery of these two components is carried out by a detector, characterized in that the signal modulated onto a carrier wave is fed to the two detectors via separate amplifiers and that for control and / or For measuring purposes, an image carrier wave is obtained via an oscillating circuit which is included in the detector circuit from which the component consisting of the modulated subcarrier wave is taken. 2. Receiver according to claim 1, characterized in that each of the amplifiers is transformer-like is coupled to the detector in question. 3. Receiver according to claim 1 or 2 of the overlay range type, characterized in that the image carrier wave obtained via the oscillating circuit is fed to a detector whose Output voltage is used for tuning display. 4. Receiver according to claim 1 or 2 of the overlay range type, characterized in that the image carrier wave obtained via the oscillation circuit is fed to a frequency discriminator whose output voltage is used for the automatic frequency control of the local oscillator will. 5. Receiver according spoke 4, characterized in that the oscillating circuit has a Forms part of the frequency discriminator. Considered publications:
German interpretative document No. 1010 566. 1 sheet of drawings © 109 710/223 10.61