JPS58124389A - Synchronizing signal generator - Google Patents

Abstract

PURPOSE:To generate a synchronizing signal of the PAL system and to use the generator in common for a synchronizing signal generator for the other systems, by constituting a circuit suitable for integration with two frequency generators and a plurality of frequency dividers and a phase comparator. CONSTITUTION:An output frequency 4fscp of a frequency generator 1 is converted into a frequency fscp at a 1/4 frequency divider 2 and outputted 3. Further, the frequency is divided into a frequency 4fscp/64489 at a frequency divider 4, and applied to a phase comparator 5. An output phase error voltage of the comparator 5 is applied to a voltage controlled oscillator VCO 6 to control the output oscillating frequency variably. The VCO 6 is oscillated at about a frequency (11Xn) times the horizontal synchronizing frequency fHP of the PAL system and the oscillated frequency is applied to a frequency divider 7, where the frequency is frequency-divided by 1/(625Xn) to be a frequency, about (11XnXfHP)/(625Xn) and applied to the comparator 5. The signal is compared with the signal from the frequency divider 4 for the phase. The oscillated frequency of the VCO 6 is controlled to eliminate the phase error of the comparator 5 and the frequency is phase-locked to the output signal of the frequency generator 1.

Description

DETAILED DESCRIPTION OF THE INVENTION A P.A. It is an object of the present invention to provide a synchronizing signal generating device which can generate a synchronizing signal of the L method and can also be used as a synchronizing signal generating device of other methods with a simple configuration.

The color subcarrier frequency of the PAL color television signal (f8 to distinguish it from the NTSC power system, etc. described later)
cp) are well known, 11 As is well known, -4-fHP and TfVP (however, fH
Since P has an offset of 1 (horizontal synchronization frequency of the PAL system) and fVP (vertical synchronization frequency of the PAL system), the relationship between fSCP and 9 is 1 fScp = (284--7 + where) 9, = 283.
7516f□2), so N fSCP and fHP do not have a simple integer ratio relationship. Therefore, the color amount is 11
The horizontal synchronization frequency fHP is obtained by dividing the carrier slope frequency iscp.
It is difficult to obtain such a frequency, and conventionally a balanced modulator or the like has been used to calculate the sum or difference of frequencies. As a result, (4) American synchronization signal generators have complicated circuits, both analog circuits and digital circuits coexist, and the analog circuits require precise adjustment.
It was difficult to accumulate in C.

The present invention eliminates the above-mentioned drawbacks, and embodiments thereof will be described below with reference to the drawings.

The synchronizing signal generating device according to the present invention has a circuit configuration that satisfies the basic equation shown in the following equation.

”” ×64489 ” 6'25xn×fHP
(2) However, in formula (2), n is any positive integer. In equation (2), the color subcarrier frequency fscP of the PAL system is 283.7516 as shown in equation (1).
Since it is fHP, 4fscp is 1135.0064.
fH, becomes. Substituting this value of 4 fscP into equation (2) yields 1135,0064 An embodiment of the apparatus of the present invention for realizing this is shown in FIG. 1 (5).

FIG. 1 shows a block system diagram of a first embodiment of the device of the present invention. In the figure, 1 is a frequency generator, and the color subcarrier frequency f
8c2p (=4.43361875 MHz)
This circuit generates a frequency 4f3cp that is four times as large as 4fscP, and is composed of an oscillation circuit that directly oscillates at this frequency, or a circuit that generates a frequency 4fscP from another frequency by means of frequency division or the like. After being outputted from the frequency generator 1, it is supplied to the phase comparator 5.

The output phase error voltage of the phase comparator 5 is determined by the voltage control release device (V
OO) 6 as a control voltage to variably control its output rooting frequency. VOO6 oscillates at a frequency that is 11×l times the horizontal synchronization frequency fHP of the PAL system,
The output frequency is converted into a frequency division ratio and is supplied to a phase comparator 5, where the phase is compared with the signal from the divider (6) 4. The oscillation frequency of vCO6 is controlled so that the phase error in the phase comparator 5 is eliminated by the loop consisting of phase ratio 11!2 5゜vCO6 and frequency divider 7. As a result, the oscillation frequency of vCO6 is is phase-locked to the output signal of the frequency divider 4 and further to the output signal of the frequency generator 1. Also, this results in 4 f3 CP 11 X n x fHp64
489 625 X n is established, and 64489 1.1 f-x-x f = 283.7516 fH.

SCP 4 625 HP , which satisfies the relationship between the PAL color subcarrier frequency fscp and the horizontal synchronization frequency 9 shown in equation (1) above.

The output signal of the above vCO 6 is passed through a frequency divider 8 with a frequency division ratio of 11×n to a frequency fHP, and is outputted to an output terminal 9. This frequency fHP has a relationship with the frequency fscp taken out from the output terminal 3 that satisfies equation (1).

In this way, according to this embodiment, the PA, which has the relationship shown in equation (1) above, is constructed entirely of digital circuits without using any analog circuits to obtain the sum or difference of frequencies. It is possible to obtain the color subcarrier frequency fsep and the horizontal synchronization frequency 9 of the L method.

Note that the output oscillation frequency of vCO6 was variable controlled by the output phase error voltage of the phase comparator 5, but the frequency generator 1 was
A variable frequency shield such as CO is configured, and vCO
If a generator with high frequency stability (for example, a crystal generator) is used that outputs a frequency of 11XnXfH instead of 6, the output frequency of the generator that generates a frequency of 170×4fscP as shown by the broken line in Figure 1 will be by controlling the frequency 11×nx
It is clear that the phase can be synchronized to fH1.

By the way, the value of the integer n can be arbitrarily selected, but the output signal of vCO6 often has distortion, and even if an output signal with a constant period is obtained, it is a symmetrical square wave with a duty cycle of 50%. is often difficult to obtain. In such a case, (8) It is well known that a symmetric square wave can be obtained by dividing the frequency by i by one stage of flips, so it is desirable that n be an even number (this simply means that the horizontal synchronization frequency fHP is A symmetrical square wave is not necessary if the signal is only obtained, but as a synchronization signal, it is necessary to generate a burst flag pulse or a blanking pulse, which will be described later, on a narrow time axis.)

Furthermore, there is a vertical synchronization signal as a synchronization signal, and its frequency afv
, has a frequency relationship that is 625 times the horizontal synchronization frequency fHP, so 2fHP is required to generate the vertical synchronization signal. From the above, it is desirable that the value of the integer n be a multiple of 2 x 2, that is, n = 4m (
However, m is any positive integer). Here n = 4 m
By substituting the above equation (2), equation (3) is obtained.

4f X-knee = 11X4Xm X f (31SC
P64489 625x4xm HP figure 2 is (3
) shows a block system diagram of a second embodiment of the device of the present invention for realizing the equation. In the figure, the same components as those in Figure 1 are given the same reference numerals, and their explanations will be omitted. However, n=4m
It's Toshide. In Figure 2 (9), the frequency 11X4 extracted from vCO6
The signal of Xm
After that, it is supplied to the frequency divider 13 with a frequency division ratio of 11.
×m At this point, the frequency decreases to 2filP.

1Xm This signal with a frequency of 2fHP is further converted to the horizontal synchronizing frequency fHP by the subordinate F 14 and outputted from the output terminal 15 after 1m.At the same time, it is also supplied to the + frequency divider 16, where 3 The frequency is divided by 1 and the vertical interval is 1<TI, which is then outputted from the output terminal 17.

On the other hand, although it is not directly related to the present invention, the frequency divider 13°1
The respective outputs of the flip-flops No. 4 and No. 16 are supplied to a logic circuit [8°]9 to generate various pulse waveforms. The logic circuit 18 generates and outputs various pulse trains related to horizontal synchronization, and the logic circuit 19 generates and outputs various pulse trains related to vertical synchronization. Logic circuit 18.1
Each of the pulse trains 9 is supplied to the logic circuit 20 as required, and outputted as various pulse trains such as a composite synchronizing signal 9, a composite blanking signal, a burst flag signal, and the like. Naf
188, read-only memory IJ (ROM) may be used for the logic circuits 18, ], 9, and 20.

Next, a third embodiment of the device of the present invention will be described with reference to FIG. In FIG. 3, the same components as those in FIG. 1 are denoted by the same reference numerals, and their explanations will be omitted. The above first and second embodiments are based on the synchronization signal of P A, T, method, color subcarrier frequency f
Although only the SCP is generated by the digital circuit, the synchronization signal of the NTSC system and the color subcarrier frequency fSC
It is clear that it would be even more desirable to be able to generate N by sharing a large portion of the circuit with only simple circuit switching. Furthermore, 5ECA, M system conveyance color (No. 8 is well known,
The first color subcarrier frequency in the color difference signal (1 to -Y) is 282
FM signal obtained by frequency modulating 1H8 (fH8 is 1OA, horizontal synchronization frequency in M system) and color difference signal (B-Y) with second color subcarrier frequency 272fHS
5- Frequency modulation A4 Since the PM signal and the M signal are line sequential signals that are synthesized alternately and in time series every horizontal scanning period, it is possible to generate at least one of these two color subcarrier frequencies. Even more desirable.

(11) The value of fJm that satisfies the above conditions is "14".
Or, it is desirable to set it as a multiple of "14".

If you add 1 to the horizontal sync frequency, the NTSO
The force formula is 15.734 kl-1z, F A T,
Since the method is 15.625 k)fz, there is almost no difference in the frequencies between the two. Moreover, the waveforms of the horizontal signals of both systems (the period of the front porch, the amount of paddy on the back porch, etc.) are very similar.

Therefore, in both the NTSC system and the PAL system, it is possible to divide the -horizontal run by the same number of revolutions, and in this case, the frequency divider 13 can be used in common, and the logic circuit 18 (・The circuit configuration can be simplified because the common N ~ 11 minutes increases. Therefore, the above number of divisions is changed to N
The programmable counter 22.2 is common to both the TSO system and the PAL system, and is shown in FIG.
Even if the frequency division ratio of 6 is switched between the NTI method and the P A, L method, it becomes a - integer in both cases, and furthermore, the sum of the two of the 5EOA and M methods, 1M1] is 272 fH out of the carrier frequency.
8(= 272 fI(,), the frequency division ratio (12) of the frequency divider that divides the frequency that is an integer multiple of fl(,) is also the value of the integer m in order to divide the frequency into an integer fraction of -. is “14
” It is desirable for the father to be a multiple of 14.

Now, the value of the integer m [is a multiple of "14"] 4
X, (! (f: and l is any positive integer),
Knead l\I 1 (substituting into formula 31 gives 111 x 4 x 14 x l ”SCP x64489-625x4x14x/ xf
HP becomes (4). That is, vCO25 shown in the 31st tree, which is the second frequency generator
61c equivalent) output oscillation station wave number, when PAL synchronization signal is generated, 616 x 1 x f1 (), (:11 x 4>
4×1YfH1). Similarly, 1 student 1 self 1 l (
When the NTSC synchronization signal is generated, ■0025 (1) The output A and the number of 1 cutting wave are 616X/'X9. In addition, l
is any positive 1 yen number, but in reality, 1 is sufficient for l0)43. This is the prefectural frequency of VOO25.
This is because the value of 62'2 would be too high for the vCO incorporated into Ic.

On the other hand, the combined subcarrier frequency fSCN of the NT8C system has a relationship with the horizontal synchronization frequency f□ as shown in the following equation.

4 f,, -'1110 fl, N(5), CN
- Therefore, fL! If a configuration similar to equation 1 is adopted, the following equation holds true (]]3.

However, in formula (6), J is any positive integer.

In addition, in order to obtain 272J'Hp, which is one of the two color subcarrier frequencies of the SECAM system, 'I4
It will be done. L r is a factor of 77×l.

The above configuration is reproduced in the embodiment shown in No. 3 (1). In the figure, reference numeral 21 denotes a wave number oscillator that generates a frequency of one signal of the color subcarrier Ji%l, which is the same as shown in FIG.
When the 1 signal generator is used for the NTSC system, it generates 4 fscN, and when used for the P-A, 1 system, it generates 2 AfscP. SEOAM in history
4. When using as a method. x 272 fHp
occurs. Whether it is used for the N'I'' SC system, PAL system, or SECAM system is determined by the system of the device such as a television camera into which this synchronizing signal generator is installed, and the frequency generation (14 ) The output excavation frequency of the device 21 is switched to 4fSCN or 4fSCP or 4 x 272 fHp.The method for this switching is to use a first crystal camera with a frequency of fscP and a second crystal with a ns number of f8cN. Photographer and 4
x a third crystal oscillator with a frequency of 272 fHp, or use a socket to replace the first. Possible methods include manufacturing the second and third crystal oscillators respectively and switching them over with a switch.

To explain the operation when using the PAL method,
The 4fscp frequency signal extracted from the frequency generator 21 is supplied to the programmable counter 22. Here, the programmable counter 22 is preliminarily cut to a uniform division ratio similar to that of the frequency divider 4 by a control signal from a terminal (or pin in the case of IC) 23 when using the PAL system.
It is placed. In addition, the control signal from terminal 4489 and terminal 23 is sent to programmable counter 26.
, 28 are supplied to the logic circuits 27 and 29 respectively, and switch and suppress the frequency division ratios of the programmable counters 26 and 28 to -□ゎ stone (= 625 x 4 x 14 pairs). are switched so that each (15) type synchronization signal for the PAL system can be obtained.

On the other hand, VC! 025 is 6] 6 x brush 11. Nearby lap/#
The total finger output is frequency-divided by 17 by a programmable counter 26 and then supplied to a phase ratio V unit 24, where the phase is compared with the output signal of the programmable counter 22. The output phase error voltage of the phase comparator 24 is VC! 025, and its output excavation frequency is variably controlled so that the phase error in the phase comparator 24 is eliminated. As a result, the output frequency of the VCO 25 is phase-synchronized with the signal of the frequency generator 210) 4f8oP 616:) IXfH.

The frequencies of the two input signals from the phase comparator 24 are equal, as is clear from equation (4). Note that the frequency generator 21 may be controlled by the output phase error voltage of the phase comparator 24, as in the devices shown in FIGS. 1 and 2.

The output signal of the VOO 25 is converted into a symmetrical square wave with a wave number of 308×lxf () by T frequency division 'IA 12, and then divided by a divider 13 having a frequency division ratio of 308Xl.7 The output signal of the frequency divider 12 and each hit output (16) signal of the frequency divider 13 are respectively supplied to the logic circuit 27.
The divider 13 may have a circuit configuration in which appropriate feedback is applied to a series of binary divider circuits so that the circuit goes around η. The logic circuit 27 also includes the frequency dividers 12 and 13 described above.
This circuit receives each bit output as an input signal, determines the counter value, and generates various pulses, and the horizontal scanning period is 616XA! Various pulses can be generated in divided step widths. When the value of l is "1", it is 616fH1
becomes 9625MI-rz. Therefore, when the value of l is "1", the 2fHP signal supplied from the logic circuit 27 to the programmable counter 28 is output from the divider 13 (consisting of a number of channels) to the output of the divider 12 by 7. Since the period for counting the symmetrical square wave 308<16 is one horizontal scanning period, this is the pulse train output from the logic circuit 27 when the value of the frequency divider 13 becomes "0" and "153J".

The programmable counter 28 receives 2" from the logic circuit 27.
The HP signal is subjected to open frequency division, and each bit output thereof is supplied to the logic circuit 29. The logic circuit 29 generates various pulses (for example, vertical drive signals, etc.) in the vertical scanning period based on the same principle as the logic circuit 27 (17). Each output pulse of logic circuits 27 and 29 is supplied to logic circuit 30, which generates a composite synchronization signal, a composite blanking signal, a burst flag signal, etc. between logic circuit 20 and senryu. Note that a ROM may be used for the logic circuits 27, 29, and 30.

Next time you use it for the NTSO method, i*! To explain the operation, in this case, the frequency generator 2 is switched to generate a frequency of 4f8CN as described above, and on the other hand, the Wd ratio of the programmable counter 22 is changed by the control signal from the input terminal 23. The internal circuits of the logic h1 paths 27 and 29 are switched in order to generate pulses with timing compatible with the NTSC system.As a result, the programmable counter 22
σ) The output signal surface wave number is the frequency shown on the left side of equation (6), and the output signal frequency of the programmable counter 26 is the frequency shown on the right side of equation (6). From VOO25, 4f8
9, 616X6゛Xf)IN, which is phase homologous to 9, is extracted. This first thing. According to NTSC method ())
In this case, as in Pi-L method 4, the solidifiers 12 and 13 are
(Horizontal *2) b'shield 11 river i7 616X/!9J
- Inferior) 1 Pig 11 mi li Hatake ≦ each + topals KN
t') can be generated by the logic circuit 27. 11 +7
) When IK is closed to [-11, it is 616 j'HNi
-t9. It becomes b923 Ml-1z.

Below, we will proceed to the same operation as when using the PAL system.
A 2-color subcarrier 1-wave frequency 'SCN of each A and [.

Next, the color of S EOA M method 21) fiXll mv
i=one color subcarrier e frequency 272f
To explain the operation when obtaining HpG, in this case the output of the frequency generator 21 is as described above, r\4X272
On the other hand, the frequency division ratio of the programmable counter 22 is set to 7 by the input terminal 23, and the programmable counter 260).
Frequency division ratio is -7777-, block counter 28
The frequency division ratios of the two are respectively switched to 5. As a result, the output signal frequency of the programmable counter 22 is the frequency 8x(x, "
l(,,1L: and programmable counter 2
The output signal frequency of 6 is the frequency 8x r x fl (,, l-f,
;Su, VOO25?'->HaI' X 4 X 27
2fI11- to phase 1111. 616 X exf
Up is '5/l' ■im is taken out. Therefore, this J′ is r=1cl+),,! l: Kiha”-
Frequency functional 2'72 f,, Cn calculated from frequency divider 2
Bow or output bribe, 1 child 3〆＼ output is good.

This laughing example is also the first. 2nd implementation B: As in the old case, the TC ratio is easy because it is composed of only the TSI circuit, excluding the VCO time circuit. Tatsushi, frequency source,
If the Crystal Bohiko etc. in the bioreactor 21 are converted to iC, the outside (・1
It is a good argument that it is important to be careful. Note that the present invention is not limited to the numerical values of the frequency in each implementation l+1, but since it is good as long as each of the above formulas can be satisfied, the frequency generator 1
, 21 output layer θ is an example, and when operating in the N'r80 method, it is fine (however, k is 35000xd
and is a factor of 44XjX/(20)).

As mentioned above, the synchronization signal generation device according to the present invention uses FAT
, 4 of the color subcarrier frequency of the color television signal
a first frequency generator that generates a frequency twice as high as 616 times the horizontal synchronization frequency of the color television signal;
a second frequency generator that generates a frequency of 1 times (where l is any positive integer and k is a factor of 35000 A second frequency divider that divides the frequency into 35,000Xl and each output signal of the first and second division dividers are phase-compared, and a phase error signal corresponding to the phase difference is outputted to the first or second frequency generator. and a phase comparator that varies its output frequency so as to eliminate phase errors, and a first and second frequency generator generates a frequency ratio between the color subcarrier frequency and the horizontal synchronization frequency, respectively. Since a signal with a frequency that satisfies the relationship is extracted, almost all synchronization signals that have a predetermined frequency ratio relationship with the color subcarrier frequency are generated by digital circuits (2
1) Since only the frequency generator that can generate Kokichi and whose frequency is variably controlled by the output of the phase comparator circuit is an analog circuit,
By externally attaching some filter time constant circuits, etc., the entire circuit can be integrated into one IC. Therefore, when integrated into an IC, it can be made smaller and more reliable than conventional synchronization signal generators. , furthermore, the first frequency generator is I
j AL A first frequency that is 4 times the color subcarrier frequency of an L color television signal or m2 that is 4 times the color subcarrier frequency of an NTSO color television signal;
o) Generate a frequency, and when generating the first frequency, 616×1 of the horizontal synchronization frequency of the PAL color television signal.
When generating the second frequency, the horizontal synchronization frequency of the NTSO color television signal is 616X.
A! Second cycle 1 which generates twice the frequency.

A first frequency divider with a switchable division ratio that divides the second frequency into 7 (" is an arbitrary positive integer), and a second frequency generator whose output signal frequency is set to PAL mode operation. m< However, k is a factor of 35000X7, (2
2) Cat, 44xjx? 7i factor) 2 minutes 8u, N '1
"S C method 1fl120+) divided gain and the output signals of the first and 20th) frequency dividers are compared in phase, and the output signal of the first or (J2nd) frequency generator is determined by the phase error signal. I) A,
Both the L method and the J-NTSC power method can switch and generate synchronization signals that have a predetermined frequency ratio relationship with the color subcarrier frequency, and furthermore, the SECAM method color image can be generated from the first frequency generator by simply switching the circuit. - 4x272xr times the horizontal synchronization frequency of the vision signal (r is 77xl)
The division ratio of the first frequency divider is switched to 136, the division ratio of the second frequency divider is switched to q, and the division ratio of the first frequency divider is switched to Alternatively, since the second frequency generator is configured to extract a frequency that is 272 times the horizontal synchronization frequency of the SECAM color television signal through the frequency dividing circuit, it is possible to use the SECAM system without the risk of installing a new circuit such as a phase comparator. One of two color subcarrier frequencies can be generated, and also between the horizontal (23) signal frequencies (161! times 1) AL, NT
S.O.

This is a division number that fully satisfies the A-all synchronous signal standards of each system of 5Efli4, and has features such as being able to be used satisfactorily even in high-end television cameras and the like.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are diagrams of the Bucock company showing respective embodiments of the apparatus of the present invention. Calibrator, 6, 25, pressure control oscillator (VCO), 7°
... Frequency divider, 13...-. Ayo (=ding, wa7.
) Frequency divider 25Xn unit, 22, 26, 28...Blocklambable counter. (24)

Claims (1)

[Claims] 1. A first frequency generator that generates a frequency that is 4 times the color subcarrier frequency of a PAL color television signal, and a frequency that is 616 times the horizontal synchronization frequency of the color television signal. ll E (l is any positive integer,
a second frequency generator that generates a frequency where k is a factor of 350 ('to X g); a first frequency divider that divides the output signal frequency of the first frequency generator into 64489-
The output signal frequency of the second frequency generator is 3. . . A second frequency divider that divides the frequency into 81, and each output signal of the first and second division dividers are compared in phase, and a phase error signal corresponding to the phase difference is outputted to the first or second frequency. A phase comparator is supplied to the generator to variably control its output frequency so as to eliminate phase errors, and the first and second frequency generators output the -F color scheme subcarrier frequency and the horizontal synchronization frequency, respectively. A synchronizing signal generator characterized by extracting a signal having a frequency (1) that satisfies the frequency ratio relationship of the F A I one-way system. 2) Generate a first frequency that is at least 4 times the color subcarrier frequency of an NTSO color television signal or a second frequency that is 4 times the color subcarrier frequency of an NTSO color television signal; and when the first frequency is generated by the first frequency generator, 1-616×e times the horizontal synchronization frequency of the JPAL color television signal (l is any arbitrary value). 616 x 1 of the horizontal synchronizing frequency of the NTSC color television code when the second frequency is generated by the first frequency generator (a positive integer).
a second frequency generator that generates a double frequency; and when the output signal frequency of the first frequency generator is the first frequency, the frequency is divided by -1-, and the output signal frequency of the first frequency generator is Time 4
489 divides this frequency into (j is any positive integer) a first frequency divider whose frequency division ratio is adjustable and the output signal frequency of the second frequency generator when operating in PAL mode. 35,000xl (where k is a factor of 35,000xl and (2) is a factor of 44XjxA), and in NTSO operation, the lyrics are divided into 44Xjxll with a second divider that can cut down the division ratio. , the respective output signals of the first and second frequency dividers are compared in phase, and a phase error signal corresponding to the phase difference between them is supplied to the first or second frequency generator so that the phase error is eliminated. and a phase comparator that variably controls its output frequency, and P from the first and second frequency generators respectively.
A synchronization signal generation device that switches and extracts a signal having a frequency that satisfies a frequency ratio relationship between a color subcarrier frequency and a horizontal synchronization frequency in an AL system or an NTSC system. 3 4 x 272 x r of the horizontal synchronization frequency of the SBOAM color television signal from the first frequency generator
(where r is a factor of 77×l), the frequency division ratio of the first frequency divider is continuously switched, and the frequency division ratio of the second frequency divider is changed to − Switch to T57 and perform SEO from the first or second frequency generator through the frequency divider circuit.
2 of the horizontal synchronization frequency of the AM color television signal
(3) A synchronizing signal generating device according to claim 2, which extracts a frequency that is 72 times higher.