JPH01276470A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent the degradation of a signal and the influence of an external noise at the time of modulation and demodulation by frequency-converting a digital signal, which is QPSK-modulated, as it is without being demodulated. CONSTITUTION:A reproducing signal from a reproducing head 15 for PCM is inputted through a pre-amplifier 16 and a BPF17 to a QPSK-demodulating circuit 18 and demodulated to the digital signal. Such a demodulating signal is de-interleaved with using a memory 20 and an error is corrected in a PCM demodulating circuit 19. Then, the signal is sent through a D/A converting circuit 21 to a sound output circuit 22 as a PCM signal and a reproducing tone is obtained.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides QPSK (q
The present invention relates to a magnetic recording and reproducing device that records a modulated digital signal on a recording medium, and is used in, for example, a video tape recorder, an audio tape recorder, and the like.

(Prior art) In a conventional magnetic recording/reproducing device with a built-in BS tuner,
The satellite broadcasting signal is FM demodulated into a baseband signal, and the signal QPSK modulated with this baseband signal is QPS.
The digital signal was extracted by K demodulation. The extracted digital signal is then subjected to processing such as error correction to extract the original digital signal, which is then modulated again using the modulation method of the magnetic recording/reproducing device and recorded on the magnetic tape. Furthermore, when the digital signal is an audio signal, it is D/A converted to an analog audio signal and then recorded on a magnetic tape.

In this way, in order to record a digital signal on a magnetic tape, it is necessary to perform modulation again using the modulation method of the magnetic recording/reproducing device to be recorded.

(Problem to be Solved by the Invention) For this reason, there is a problem that errors increase due to external noise during modulation. Furthermore, when the digital signal is an audio signal, there is a problem in that the sound quality deteriorates due to signal conversion such as D/A conversion and A/D conversion.

(Means for Solving the Problems) The present invention has been made in view of the above-mentioned circumstances, and is a magnetic recording and reproducing device that records QPSK-modulated digital signals transmitted from satellite broadcasting on a recording medium.
It is provided with a frequency conversion means for frequency converting the QPSK modulated digital signal as it is to a low frequency band, and a recording means for recording the digital signal frequency-converted to a low frequency band by the frequency conversion means on the recording medium. .

(Function) Without demodulating the QPSK modulated digital signal,
By converting the signal directly to a low frequency and recording it on a recording medium, signal deterioration during modulation and demodulation and the influence of external noise are prevented.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic block diagram of a reproducing thread of a magnetic recording and reproducing apparatus of the present invention, and this embodiment shows a video tape recorder capable of receiving satellite broadcasting signals and recording PCM audio signals.

In the figure, 1 is a BS antenna for receiving satellite broadcasting;
is a BS converter, 3 is a BS tuner, 4 is an FM demodulation circuit, 5 is a low-pass filter (LPF), 6 is a video signal modulation circuit, 7 is a recording amplifier, 8 is a video head, 9 is a band-pass filter (BPF), 10 is a frequency conversion circuit, 1
1 is a BPF, 12 is a recording amplifier, 13 is a PCM recording head, and 14 is an oscillation circuit.

Next, the operation of the reproducing system of the above-described magnetic recording and reproducing apparatus will be explained with reference to the signal waveform diagram of each part shown in FIG. However, FIG. 3(a) shows the input signal to the frequency conversion circuit 10,
The figure (b) is the output signal of the oscillation circuit 14, the figure (C) is the output signal of the frequency conversion circuit 10, and the figure (d) is the BPF II
The output signals of each are shown.

That is, the BS signal received by the BS antenna 1 is
The S converter 2 performs BS-IF signal conversion. This converted BS-IF multiplied signal is input to the BS tuner 3, where a desired channel is selected and sent to the FM demodulation circuit 4, where it is FM demodulated and becomes a baseband signal.

The video signal component of this baseband signal is separated by a 4.5 MHz LPF 5, modulated by a video signal modulation circuit 6 at the next stage, appropriately amplified by a recording amplifier 7, and then output by a video head 8. It is recorded on a magnetic tape (not shown).

On the other hand, the audio signal component of the baseband signal is 5.
Separated by BPF9 of 73MHz±500KHz [3rd
(see figure (a))] is input to the frequency conversion circuit 10. In addition to this, the frequency conversion circuit 10 also receives an 8.23 MHz oscillation signal from the oscillation circuit 14 [see FIG. 3(b)]. Therefore, the frequency conversion circuit 10 performs frequency conversion between this oscillation signal and the signal from the BPF 9, and converts the signal into a signal of 5.73MHz±500KHz and a signal of 2.5MHz.
A signal of Hz ± 500 KHz is obtained [Figure 3 (C
)], and in the next BPFil, a signal of 2.5 MHz ± 500 KHz is separated and extracted from this frequency-converted signal [see Fig. 3(d)], and the signal is sent to the recording amplifier 12.
After being appropriately amplified, the signal is recorded on a magnetic tape by a PCM recording head 13.

FIG. 2 shows a schematic block diagram of a reproduction system for reproducing signals recorded on a magnetic tape in this manner.

In the figure, 15 is a PCM playback head, 16 is a playback preamplifier, 17 is a BPF, 18 is a QPSK demodulation circuit,
19 is a PCM demodulation circuit, 20 is a memory, 21 is a D/A conversion circuit, and 22 is an audio output circuit.

That is, the signal reproduced from the magnetic tape by the PCM reproduction head 15 is appropriately amplified by the reproduction preamplifier 16, passed through the BPF 17, and inputted to the QPSK demodulation circuit 18, where it is demodulated into a digital signal. This demodulated digital signal is then deinterleaved using the memory 20, and is then deinterleaved using the PCM demodulation circuit 19.
If there is an error, the error is corrected by an error correction code and the PCM
The signal is then converted into an analog signal by the D/A conversion circuit 21, and outputted by the audio output circuit 22 as reproduced audio.

(Effects of the Invention) As explained above, according to the magnetic recording and reproducing device of the present invention, the frequency of the QPSK modulated digital signal is directly converted without demodulating it, so QPSK demodulation is performed as in the conventional device. Since the processes of digital demodulation and re-modulation can be omitted, it is possible to prevent signal deterioration during modulation and demodulation and the influence of external noise, thereby making it possible to record high-quality data on a magnetic tape.

[Brief explanation of the drawing]

Fig. 1 is a schematic block diagram of the recording system of the magnetic recording/reproducing device of the present invention, Fig. 2 is a schematic block diagram of the reproducing system of the same device, and Fig. 3 is a signal waveform diagram of each part of the recording system of the same device. . 1...BS antenna 2...BS converter 3...
・BS tuner 4...FM demodulation circuit 5...LPF
6... Video signal modulation circuit 9, 11. 1
7...BPF lo...Frequency conversion circuit

Claims (1)

[Claims] 1) In a magnetic recording and reproducing device that records a QPSK modulated digital signal transmitted from satellite broadcasting on a recording medium, frequency conversion that directly converts the frequency of the QPSK modulated digital signal to a low frequency band is provided. 1. A magnetic recording and reproducing apparatus comprising: a recording means for recording a digital signal frequency-converted to a low frequency by the frequency converting means on the recording medium.