JPS6117530Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a recording and playback processing circuit in which there is no change in the relative phase of a reference signal and a phase-modulated signal.

Conventionally, two signals were recorded simultaneously on magnetic tape,
Alternatively, as a means for reproducing from a magnetic tape, two-channel recording and a method of young children are used. However, in the high audio frequency band,
During the recording and playback process, the instantaneous relative phase changes between signals are significant. For example, if a reference signal and a phase-modulated signal are recorded and then the signal obtained by playback is phase-detected, the detected output signal In this case, the instantaneous phase change is detected as a noise component, and it is difficult to distinguish it from the desired signal.

When two signals in a high audio frequency band are recorded on a magnetic tape with two channels and played back, the difference in phase characteristics related to the frequency characteristics between the two channels is the cause of the change in the instantaneous relative phase between the two signals.The speed of the magnetic tape unevenness, uneven expansion and contraction of magnetic tape,
Possible causes include differences in head position.

The present invention eliminates the drawbacks of the two-channel recording and playback process by signal processing and combining two signals, recording them in a single channel, and separating and processing the reproduced composite signal. It provides a processing circuit.

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 are signal processing circuit diagrams during recording according to an embodiment of the present invention.

In Figure 1, a 10KHz reference signal is converted into a 5KHz second reference signal with half the frequency in frequency conversion circuit 1, and the amplitude is combined with the 10KHz phase modulated signal in synthesizer 2 to create a composite signal. . At this time, the frequency conversion is not limited to 1/2, but may be a frequency different from the frequency of the phase modulated signal (the combined output cannot be obtained with the same frequency).

FIG. 2 shows an example in which a phase shift element that causes a phase difference between input and output is included in the process of frequency conversion and synthesis of the reference signal in the embodiment shown in FIG. By installing the phase shift circuit 3 having phase characteristics equivalent to the phase characteristics of the reference signal path in the signal path, it is possible to eliminate relative phase changes in the composite signal.

FIG. 3 shows a signal processing circuit for recording and reproducing a composite signal on a magnetic tape according to the embodiment of FIG. 1 or 2.

In FIG. 3, the composite signal is sent to the second
The second reference signal is separated into a reference signal and a phase modulated signal, and the frequency of the second reference signal is doubled in the frequency conversion circuit 5. This is the 10K explained in the example of Fig. 1 above.
A 10KHz reference signal is obtained by converting the Hz reference signal to 5KHz, which is 1/2, and performing the reverse conversion. On the other hand, the phase modulated signal is obtained in a separated state by the separation circuit 4.

FIG. 4 shows an embodiment in which the separation circuit 4 and frequency conversion circuit 5 in FIG. 3 include a phase shift element with respect to the reference signal, and the phase modulated signal path has a phase characteristic equivalent to the phase characteristic of the reference signal path. By providing the phase shift circuit 6 with a phase shift circuit 6, even if a frequency change occurs due to unevenness in the speed of the magnetic tape when reproducing from a magnetic tape, the reference signal and the phase modulated signal can be shifted without causing any relative phase change between the reference signal and the phase modulated signal. I can get a signal.

In addition, in the above explanation, 10KHz is used as an example.
Although the reference signal and the phase modulated signal are cited, the frequency is not limited to these, nor is the frequency conversion limited to 1/2 and 2 times.

As explained above, the present invention makes it possible to simultaneously record and store the reference signal and phase modulated signal for phase detection on a magnetic tape, play it back as necessary, and perform secondary signal analysis, etc. easily possible.

[Brief explanation of the drawing]

1 and 2 show signal processing circuits during recording according to the present invention, and FIGS. 3 and 4 show signal processing circuits during playback according to the present invention. 1, 5... Frequency conversion circuit, 2... Composite signal,
3, 6...phase shift circuit, 4...separation circuit.

Claims (1)

[Scope of utility model registration request] a circuit for converting a reference signal into a second reference signal having a frequency different from that of the reference signal; and a circuit for synthesizing the phase modulated signal and the second reference signal;
a circuit for recording this composite output on one channel of a magnetic tape; a circuit for separating a phase modulated signal reproduced from the magnetic tape and a second reference signal;
a circuit for converting the second reference signal to the original frequency before conversion to obtain the reference signal, and determining the relative phase relationship between the reference signal and the phase modulated signal by adjusting the phase due to the recording system and the playback system. A signal processing circuit characterized by holding data regardless of fluctuations.