JPH0434228B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a video tape recorder (hereinafter referred to as a VTR).
), or a part thereof, to record and play back PCM signals compliant with standard television signals.
In a PCM recording and playback device, automatic recording and playback automatically detects and determines whether the VTR is recording or playing under standard conditions in which input and output signals are connected to the VTR, allowing easy operation without any operational errors. This invention relates to a determination device.

Configuration of conventional example and its problems FIG. 1 shows the vertical section of a PCM signal, and FIG. 2 shows the horizontal section. In general, a VTR outputs the signal from the tape to the video output during playback, and outputs the video input signal as is to the video output when stopping or recording. Therefore, in the standard state, these input/output signals are connected to the PCM recording/playback device, so it is difficult to determine whether the data signal input to the PCM recording/playback device is the same as the data signal it is sending out or is different. Conventionally, the comparison was made bit by bit, which required a highly accurate determination device. However, when designing on a bit-by-bit basis with timing as an issue, it is necessary to create complex timing using an external circuit when using an LSI without a judgment function, resulting in a very complex configuration. It is something that becomes.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an automatic recording/playback determination device that has a simple configuration and does not require high precision for this detection determination.

Structure of the Invention The recording/playback automatic determination device of the present invention comprises a first vertical synchronization separating means for separating a vertical synchronizing signal in a PCM signal conforming to a standard television signal, and a frequency dividing means for dividing the output of a voltage controlled oscillator. means, a first phase comparison means for comparing the phases of both outputs of the frequency dividing means and the vertical synchronization separation means and outputting a phase difference pulse having a length corresponding to the phase; and this first phase comparison means. first low-pass filter means for high-cutting the output to control the oscillation frequency of the voltage-controlled oscillator; and receiving the output signal of the voltage-controlled oscillator as an input.
PCM signal generation means for generating a PCM signal;
a second vertical synchronization signal separation means for separating the vertical synchronization signal in the PCM signal output from the PCM signal generation means;
a second phase comparing means for comparing the phases of both signals output from the first and second vertical synchronizing signal separating means and outputting a phase difference pulse having a length corresponding to the phase difference;
A second low-pass filter means for high-cutting the output of the phase comparison means is provided, and the output signal of the second low-pass filter means is used as a recording/reproduction determination output.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 3 to 6. FIG. 3 shows a block diagram of the invention. 1 is sent from the video output of the VTR.
The first vertical synchronization separation circuit separates vertical synchronization from the PCM signal, which slices the PCM signal at a certain level and integrates it to obtain a vertical synchronization signal. 2 is a frequency divider that divides the output of a voltage controlled oscillator (described later) to generate a field signal; 3 is a first phase comparator that divides the output signal of the first vertical synchronization separation circuit 1 and the frequency divider 2; A phase difference pulse is generated whose length changes according to the phase difference by comparing the phase with the output signal. 4 is a first low-pass filter (hereinafter referred to as the first LPF) that integrates the phase difference pulse output from the first phase comparator 3 and converts it into direct current; 5 is the first low-pass filter;
Voltage controlled oscillator (hereinafter referred to as VCO) whose oscillation frequency is controlled according to the DC output from LPF4
The output signal is the input signal of the frequency divider 2 as described above. Therefore, 1 to 5 constitute a phase locked loop (hereinafter referred to as PLL).
6 is a PCM signal generator that generates a PCM signal by inputting the output signal of VCO 5; 7 is a second vertical synchronization separation circuit that separates vertical synchronization of the output of PCM signal generator 6; 8 is a first and second vertical synchronization separation circuit; Vertical synchronization separation circuit 1,
A second phase comparator that compares the phase of the vertical synchronization signal of both outputs of 7 and generates a phase difference pulse with a length corresponding to the phase difference; 9 is a second phase comparator; 9 is a second phase A second low-pass filter (hereinafter referred to as the second LPF) converts the output of the comparator 8 into direct current.
This output becomes the recording/reproduction determination output.

FIG. 4 shows the timing of each part during reproduction.
This is the output signal b of the first vertical separation circuit 1 which separates the vertical synchronization of the PCM signal a from the VTR, and this b is phase-compared with the field signal c of the frequency divider 2 output, and based on the output of the VCO 5. field signal c and PCM output signal d to the PCM signal generator 6 output.
is generated, and a signal e is generated at the output of the second vertical synchronization separation circuit 7. The difference signal of the output of the second phase comparator 8 which compares the phases of the vertical synchronization signals b and e in the input and output PCM signals is f, and the second phase comparator 8 keeps the aforementioned PLL in the locked state during playback. Therefore, it continues to output a constant difference output. Therefore, by integrating this signal and converting it into direct current, it is possible to support the regeneration state.

FIG. 5 shows the timing of transition to recording. At this time, even the signal that outputs itself is turned on.
The PLL loop cannot continue to go around the lock state, and the oscillation limit of VCO5 is reached or
The frequency reaches the lower limit, and a corresponding difference signal is output as shown in FIG. At this time, the PCM recording and playback device switches to a crystal oscillator instead of VCO5, and the standard format
Now generates PCM signals. The timing in that case is shown in FIG. Since the difference output of f at this time is also different from that shown in FIG. 4, it can be indicated that it is not in the reproducing state.

Effects of the Invention As explained above, according to the automatic recording/playback determination device of the present invention, the vertical synchronization section shown in FIG. 1 is separated from the input PCM signal, and the PCM signal output from itself Apply a phase-locked loop to the field signal generated at the timing shown in Figure 1, and look at the relative relationship between the vertical sync signal input at that time and the vertical sync signal in the output PCM signal. , since the current mode is determined as recording or playback, the input/output
Recording and playback can be determined by looking at the phase difference of the vertical synchronization signal in the PCM signal, and a series of PLL loops are generally used mainly to generate a master clock by applying phase lock. By utilizing this loop, the present invention can realize a simple circuit configuration by looking at only the phase difference instead of the bit unit.
The recording and reproducing device is automatically controlled and can provide reliable operation without any operational errors.

[Brief explanation of drawings]

Figure 1 is a waveform diagram of the vertical section of the PCM signal, Figure 2 is a waveform diagram of the vertical section of the PCM signal.
The figure is a waveform diagram of the PCM signal horizontal section, Figure 3 is a block diagram of an embodiment of the present invention, Figure 4 is a timing diagram of each part of Figure 3 during playback, and Figure 5 is from playback to recording. Timing diagram of Fig. 3 during transition of , Fig. 6
The figure shows the timing diagram of each part during recording. 1... First vertical synchronization separation circuit, 2... Frequency divider, 3... First phase comparator, 4... First
LPF, 5...VCO, 6...PCM signal generator, 7
...Second vertical synchronization separation circuit, 8...Second phase comparator, 9...Second LPF.

Claims (1)

[Claims] 1. A first vertical synchronization separation means for separating a vertical synchronization signal in a PCM signal conforming to a standard television signal, a frequency division means for dividing the output of a voltage controlled oscillator, and this frequency division means and the vertical synchronization separation means. a first phase comparison means for comparing the phases of both outputs of the means and outputting a phase difference pulse having a length corresponding to the phase; and a first phase comparison means for outputting a phase difference pulse having a length corresponding to the phase; a PCM signal generating means for generating a PCM signal by inputting the output signal of the voltage controlled oscillator; and separating a vertical synchronization signal in the PCM signal output from the PCM signal generating means. a second vertical synchronizing signal separating means that compares the phases of both signals output from the first and second vertical synchronizing signal separating means and outputs a phase difference pulse having a length corresponding to the phase difference; A comparison means and a second low-pass filter means for high-cutting the output of the second phase comparison means are provided.
An automatic recording/playback determination device which uses an output signal of a low-pass filter means as a recording/playback determination output.