DE2048368C3 - Identification signal detector for a PAL / SEC AM decoder - Google Patents

Description

The invention is based on the object in which

Recovery of identification signals from PAL

The invention relates to an identification signal 60 or SECAM color sync signals as many as possible Detector for a PAL / SECAM decoder for re-circuit elements, common to both systems Obtaining the identification or identification signals to be used and switching the signal path as far as possible To avoid color television broadcasts according to SECAM as much as possible. Switching the signal or The PAL system is usually immediately after or channels switching the power to everyone Line synchronization pulse in front of the image content 65 supply to circuit units between the each Line occur. switched on and before the switched-off state

Identification or identification signals are drawn with SE-. Ideally, the identification signal should

CAM transmissions are required because here the red and blue detectors or demodulators without any switching

th process both types of identification signals- Fig. 2 is a circuit diagram of the identification signal-

ten, which gives greater reliability. detector. .

According to the invention, a demodulator is of the type described above. The t-aro- arriving at input 1 in FIG.

called type characterized in that a television signal mixture can each in A ^ hlutι an

Direct current connection between the mentioned intermediate 5 the line synchronization pulse PAL or ^bb | - ^A ™ ~

between point and the second matched circle contain identification signals, di <> with half

and that line frequencies alternate over the first tuned circle, i. H. periodically

fetch a second chain of diodes with an intermediate point. With SECAM the color carrier is between

is switched, which supplies the PAL output signal and two different frequencies, in the case of PAL between

to which the output signal of the PAL oscillator is switched to two different phases. The decoder

which is ineffective in SECAM operation must be able to respond in both ways so that it can

is made so that no switching is required. its main task, namely the decoding of the

Except that it fulfills the above-mentioned task of color video signal.

According to the preferred embodiment, the invention offers the following advantages. So the same 15 (about 4 MHz) is passed through a color synchro-delay line in the main color bar channel for SE- naltorstufe 2, which are used by the slot input J CAM or PAL operation, whereby the line return pulses supplied are gated in PAL operation the output of the delay line so that only the color sync signals (the m form of device are additionally switched to their input (as known on oscillation trains during the image extraction) and this additional activation occurs at the> o interval of each line) the SECAM operation according to the invention is interrupted . This achieves the identification signal detector 4 which achieves the periodicity of the two-way switch 5 and o in the main signal channel by using the same delay line so that only a single delay line has to be set for PAL or SECAM decoding in PAL or SECAM operation. Its output signal also controls over any is needed. For the PAL operation, the phase and frequency of the delayed and the undelayed version with color subcarrier PAL oscillator 7, ie the reference carrier of its frequency, are added to the phase and frequency for the SECAM operation a color carrier line 9 for the adder circuit is controlled by a diode switch under synchronous phase demodulation. Who are falracted. The invention thus enables vibrations are also via lines lu una considerable economy, which according to an advantageous 30 11 the (R-Yy and the (Ä-I ^ PAL demodulator 2 adhere to further development) are further increased or 13 supplied to the The output lines 14 can be used to generate the color difference signals for the picture tubes with the help of a common flip-flop or 15 and correspond to the corresponding rectangular pulse generator -Image information signals are regulated, both the SECAM and 35 mation line, which reaches the red demodulator 12 from the 1 binder PAL switch in its cycle on the two input 1, the phase, because the red line operating modes are set, whereby the SECAM were transmitted according to the PAL method with alternating demodulators in the main color channels during the phase. The line from the PAL-B operation can be switched off and vice versa. Input 1 to the PAL demodulators 12 and 13 Both switches are thus through the same 4 ° contains a delay line 16 whose delayed square pulse generator or the same Fhpflop with tion amounts to a sampling line duration and which actuates another half line frequency. The PAL switch order (not shown) for adding the delayed ones is a 0 ° / 180 ° or phase reversal switch and works for the undelayed color carrier version in turn based on the red signal or on the reference carrier signal, using the PAL method RY demodulator from the PAL line 16, a haru oscillator (known per se) can be delivered. After dam SECAM encryption synchronizing signal canceller (not shown) vorgescnaifahren feed the color difference signals as frequency tet be, so that the PAL demodulators 12 and 1J of a color subcarrier modulation transmitted. The RY as well as the SECAM-FM-Disknminatoren 17 and and By signals are transmitted in alternating 18 in the image blanking intervals, the color synchronous lines, and do not process the center frequency of the FM-50 signals.

The color carrier is 4.406 MHz for the Α-Γ signal. Unlike the PAL phase reversal switch, the is 4.25 MHz for the ß-K signal. Before the beginning of the SECAM switch 6, a double toggle switch is used on each line as a color sync signal. Its two inputs the delayed and the delayed train with the color carrier center frequency, ie the delayed color image signals from input 1 receives 4.406 MHz and 4.25, respectively MHz is transmitted in alternating 55 and with its two outputs to the inputs of the lines. Red and blue SECAM demodulators "or 18 This color sync signal can therefore be switched on. The delay line 16" recovers an identification signal in the same nerf <thus always the last line ^de ; ^ 'S ^e "(TM) ^e '°' ^e way can be used as that is currently not received in its phase of and the switch line to line changing color sync signal at 60 swaps the output for each zone line. PAL method The outputs of the SECAM demodulators can be shown below an embodiment of the invention combined with the two PAL outputs 14 and 15 with reference to the drawings. To explain switching of the signal lines. It shows shun, the energy supply of the two is not

Fig. 1 shows the block diagram of a SECAM / PAL 65 demodulators used in each case switched off.

Color decoder for dual operation with according to the invention The identification signals from the demodulator 4 Identification signal demodulator or detection signal via a line 19 Λ to a phase connection

_{gate and the} same 19, where they are with the output of a

Switch flip-flops 20 are compared. The flip sistor 34 connected, which jointly the demodul

flop 20 is a bistable multivibrator that is controlled by the lated PAL or SECAM identification signals

Return pulses switched and amplified by an electrode of half the line frequency and via the

Niche switch 21 under control by the output line 19 (Fig. 1) forwards. To a

same 19 stopped and restarted 5 preventing direct current interaction is dem

a capacitor 37 is connected upstream when it is out of phase or out of step with the SECAM input.

Identification signals device. This is how the flip-flop does not generate such a capacitor on the PAL

cine for the operation of the switches 5 and 6 ideal right input from the intermediate point 31 provided because here

corner oscillation, and both switches can use the frequency-synchronizing DC control voltage

1-line 22 and 0-line 23 continuously and periodically io for feeding in after amplification via line 8

be operated. The phase comparator 19 can be removed from the PAL oscillator 7 (Fig. 1)

The absence of identification signals. A capacitor 38 conducts the color carrier

moderately a black and white received signal on and off the reference carrier to ground. Except the

the usual color lock 24 deliver. Operating voltage for the PAL oscillator (the other

It will now be described in detail with reference to FIG. 2 of the identification signal detector 4 if it interferes with the SECAM identification signals. This would have an effect) in Fig. 2 there is no switching. Color signal from input 1 reaches normal between PAL and SECAM operation. The transistor-wise blocked transistor 25 in the color sync 34 (as well as the diode 27) does not represent an additional signal gate stage 2. This transistor is required during the required component because it is also present in normal reception per: color sync signal through the PAL identification circuits is.
Terminal 3 supplied, in a network 26 with The present arrangement offers the following of a diode 27 of the type OA 91 and a voltage-important advantage. The two outputs of the diode connection 28 for +20 volts formed back line pairs are, as mentioned, opened via the resistors 35, 36 running pulses (switched to the conductive state, but no other decoupling) elements are required. The output 30 connected to the second color synchro-signal gate stage and from the tuned circuit (the frequency discriminator) collector of the transistor 25 to the tap T ₃ only supplies a signal to the center-tapped primary winding L _{1 of} a frequency-modulated SECAM identification transformer 29 coupled to its secondary winding L _t pulse get to the color sync signal gate stage. In the usual phase shifter frequency discriminator 30 in this case, the PAL oscillator does not work, so that winding forms. The transformer windings L ₁ and no pulse is generated at output 31.
L ₂ are matched by parallel capacitances, as is common with Wenn, on the other hand, a phase-modulated PAL-Identi-phase and frequency demodulator. fication signal to the color sync signal

The primary winding L ₁ is at its ends T ₁ and reaches, there is no signal at the discriminator output 30

T _{4 is} generated via a first chain of diodes D ₁ and D _t with 35. The PAL oscillator then works, and a

an intermediate point 30 as a SECAM output and a 7.5 kHz identification signal is output at output 31

generated via a second chain of diodes D ₃ and D _4. The two outputs 30 and 31 can therefore

connected to an intermediate point 31 as a PAL output. via ohmic resistors without any switches

The PAL reference or diodes are also connected to the intermediate point 31,

vibrations via line 9 (Fig. 1) for the 40 The primary winding tapped at input T ₃

Synchronous demodulation supplied, and the intermediate L _{1 of} the transformer 29 has 40 turns and

point 30 is with one end T _{6 of} the secondary winding a distance of about 4 mm from the secondary

lung Lj connected, the other end Γ _β to reference winding L ₂ with 20 turns. Between T ₁ and the

potential (ground). The center tap T _{t of} the bias _{tap T 2} are 10 turns. All

Primary winding L ₁ and the connection point 32 45 borrowed five diodes are of the type OA 91, and the two

two 1 MΩ resistors, the L ₁ connected in parallel with the transistors are of the 2N 5183 type. All of these

are connected to a balancing and prestressing network 33. Dimensions and type designations are natural

connected. given here only as an example.

The diode connection points 30 and 31 are both.

via decoupling resistors 35 and 36 of 5 <> each licher and more reliable dual operation for PAL and

100 K reached with the input (base) of an amplifier transfer SECAM.

1 sheet of drawings

Claims (5)

Patent claims are transmitted in alternating lines in each case: and the recipient must be able to recognize or identify whether a given piece of information is received 1. Identification signal detector for a PAL / SECAM decoder based on the blue or red content of the picture with two coordinated circles, 5 draws. Such signals are used in PAL transmissions the versions synchronized with the phase-locked, because the one color carrier, usually the red-PAL- or SECAM color sync signals fed color carriers, polarity reversed from line to line, d. H. in its are also reversed with a phase matched over the first and the receiver is able Circuit switched diode chain with one connected to the polarity reversed from the non-reversed polarity second coordinated circle for the purpose of providing xo red lines to distinguish, of the SECAM output signal that can be connected The identification signals not only fulfill sub- between point, as well as with a PAL oscillator, different tasks with the SECAM system on the one hand characterized in that one and the other hand in the PAL system, but they are Direct current connection between the mentioned also different in kind, namely with SECAM Intermediate point (30) and the second coordinated 15 frequency modulations and, in the case of PAL, phase modulation Circle exists and that over the first co-ordinates in the color sync signals, whereby these two th circle a second diode chain (D ₃ , D ₄ ) with the modulations each with half the line frequency an intermediate point (31) is connected, which occur the sequence. For PAL, but not for SECAM, PAL output signal supplies and which the output becomes an oscillator for the synchronous demodulation of the output signal of the PAL oscillator (7) is fed, ao color sync signals and the remaining part of the PAL which needs signals made ineffective in SECAM operation, and this oscillator must with the will. much higher-frequency color carrier that is associated with the 2. Identification signal detector according to spoke 1, PAL color sync signals is transmitted, synchronously thereby marked that it be with the PAL / nized. SECAM decoder is connected in such a way that the same as From patent specification 65 947 of the office for Erfin delay line (16) in the main color channel education and patent system in East Berlin is a television that can be switched between for SECAM and PAL operation PAL and SECAM operation, being known in the PAL operation in a known receiver in which the PAL and Way, the output of the delay line SECAM circuit parts except for the common bezu its input signal is added, and the delay line used almost all of this Addition process in SECAM operation are separate. Furthermore, from the German interpretations are interrupted will. Documents 1 263 820 and 1 278 493 circuits for 3. Identification signal detector according to claim 1 control of the PAL switch for line-by-line reversal or 2, characterized in that a corresponding phase position is known, but without this the phase of demodulated identifiers would be considered, let alone 35 SECAM systems tion signals controlled common flip-flop (20) economical solutions for switchable two-rod. Like. Square-pulse generating circuit volume receiver would be explained. The same applies element both the SECAM and the PAL the German Offenlegungsschrift 1 462 951, which Switches (6 or 5) in one as well as the other refer to a PAL circuit, in the case of the mutual Operating mode activated periodically and that the SECAM 4 «malfunctions of two control functions are prevented Demodulators (17, 18) in the main color should. channels are switched off in PAL operation. An identification signal detector has already been installed and vice versa. known to have a dual mode of action (radio mentor, 4. Identification signal detector according to claim Dec. 1967, article by Dr. Fraction), of two 1, 2 or 3, characterized by a common 45 coordinated circles, those with coherent or phasamen DC amplifier (34) for the demodule-rigid synchronized versions of the PAL or lated SECAM and PAL identification signals SECAM color sync signals are fed, one via as well as for the control DC voltage, the diode operation in the PAL- the first coordinated circuit for the phase synchronization of the PAL chain with a circuit coordinated with the second Oscillator (7) with the PAL color sync signal 5 ° for the purpose of providing the SECAM output signal is used. connectable intermediate point as well as a PAL 5. Identification signal detector according to claim 3, there is an oscillator. This known solution has the characterized in that the flip-flop (20) has the disadvantage that the signal is switched and that controlled by the line frequency and often an amplification stage for the output signal Switch (21) is switched when its output 55 of the second tuned circuit as well as frequently one signal out of phase with the identification signals separate color synchronizing signal toi stage is required. the.