JPS5975479A - Sound recorder and reproducer - Google Patents

Abstract

PURPOSE:To discriminate the continuity of monitor of an input signal at muting and the propriety of the muting function, by attenuating the input signal at the recording system muting and monitoring it at the reproducing system, in response to the muting switch. CONSTITUTION:In turning on a muting switch S, the recording system is selected to the muting state, a switch 41 is switched to a contact 1b and attenuator circuits 42, 43 are activated. Then, an input signal from a recording system A/D converting circuit 20 is monitored via a switch 41 and circuits 42, 43 of the reproducing system. Thus, the monitor of the reproducing system of the input signal is continued even at the recording system muting and the discrimination of the propriety of the muting function is attained by monitoring the attenuating state at the same time.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a recording and playback system with an improved recording signal monitoring function.
Regarding equipment.

[Technical background of the invention]

2. Description of the Related Art Recently, in the field of audio equipment, a PCM recording/playback device (that is, a digital recording/playback device) using PCM technology has been developed.

Such a PCM recording/playback device operates on the principle that during recording, an audio analog signal is first converted into a digital signal and recorded on a magnetic tape, and during playback, the digital signal reproduced from the magnetic tape is converted into an audio analog signal. This is realized by

Specifically, an audio analog signal is sampled at a predetermined period, and the sampled audio analog signal is subjected to an analog-to-denotal conversion, that is, a quantum It is now being encoded as well as encoded. At the time of recording, this digital signal is subjected to addition of an error correction code, addition of an error detection code, and well-known interleaving processing, and is then superimposed on, for example, an NTSC standard television signal and recorded on a video tape recorder (hereinafter referred to as VTR). It is something. Next, the NTSC standard television signal played back from this video tape recorder is demodulated and the extracted digital data (sampled words, error correction codes, error detection codes, etc.) is subjected to dinterleaving processing. After that, the interleaved sampled word is subjected to error detection and error correction based on the above error detection code and error 9 correction code, and the original analog signal is transformed and encoded. It is converted into a signal (sampled word) equivalent to a digital signal. This sampled word is adapted to be restored to the original audio analog word by a digital-to-analog converter.

In other words, by converting audio analog signals into digital signals, it is possible to overcome the technical limitations associated with conventional analog tape recorders such as cassette tape recorders, such as the physical characteristics of the maximum magnetization level of the magnetic tape used as the recording medium. High-quality recording and playback can be achieved by eliminating adverse effects on acoustic characteristics caused by mechanical accuracy, precision, etc.

Such a digital recording/reproducing apparatus is constructed as shown in FIG. 1, for example.

That is, for example, the two left and right audio analog signals, which are the recorded signals supplied from a microphone or the like, are connected to the terminals INL I INH and the amplifiers 11 and 12, respectively.
A well-known pre-emphasis is carried out through the input terminals of re-emphasis circuits 13.14.Each output signal of these re-emphasis circuits 13.14 has a cut-off frequency set to, for example, 20 kHz. sample and hold circuits 17 and 18, respectively, through corresponding low-pass filters (hereinafter referred to as LPFs) 15 and 16.
The signal is supplied to each input terminal of the mixing circuit 19, sampled and held every 22.6 μs, and then supplied to a pair of input terminals of the mixing circuit 19.

The respective output signals of these sandal hold circuits 17 and 18 are multiplexed by the mixing circuit 1g so that the left and right channels are alternately switched every 11.3 μs, and then sent to an analog-to-despotal conversion circuit (hereinafter referred to as ADC circuit) 20. It is designed to be supplied to the input terminal of The output signal of the mixing circuit 19 is synchronized with the switching of the left and right channels by the ADC circuit 20 (every 11.3 μs), for example, as a 14-bit serial digital signal (generally called a sampling word). It is converted into .

The sampled words that are continuously output from the output terminal of the ADC circuit 20 are subjected to processing such as well-known interleaving processing, addition of error correction codes and error detection codes, etc. by the recording processing circuit 21, and then sent to the video amplifier. 22, for example, is superimposed on the NTSC standard television signal and sent to the output terminal (
0UTv) via a video chi recorder (VT
23 video input terminal (referred to as R), and
In addition, the control input terminal of the recording processing circuit 21 is grounded via a digital muting switch (So), and the switch is turned on. A digital output (hereinafter referred to as digital zero) corresponding to the drop level (-ωdB) of the analog signal is sent to the VT via the video amplifier 22.
By supplying the signal to R23, it is possible to perform digital recording muting, which digitally mutes the recording signal.

On the other hand, the MT8C standard television signal reproduced from the magnetic tape is supplied to the synchronization signal separation circuit 24 via the input terminal (INv), demodulated, and interleaved by the recording processing circuit 21. The signals are converted into signals equivalent to the sampling word, the error correction code, and the error detection code and are supplied to the input terminal of the reproduction processing circuit 25, and only the synchronization signal (not shown) is separated and supplied to, for example, a clock signal generation circuit (not shown). A clock (g) synchronized with the synchronization signal is supplied to the reproduction processing circuit 25.

The sampled word, error correction code, and error detection code outputted from the synchronization signal separation circuit 24 are processed by a reproduction processing circuit 25 based on dinterleague processing, which is the opposite of the interleaving processing, and an error detection code and an error correction code. In this case, the sampled word is incorrectly searched and incorrect (Y) fJ is correct. This error-corrected sampling word is supplied to the input terminal of a digital-to-analog conversion circuit (hereinafter referred to as a DAC circuit) 26 that performs digital-to-analog conversion in synchronization with the clock signal.

At the same time, the reproduction processing circuit 25 supplies the clock signal and a signal for generating various control signals to an unillustrated portion.

The sampling word supplied from the reproduction processing circuit 25 is
The DAC circuit 26 converts the signal into a signal equivalent to the multiplexed analog signal derived from the mixing circuit 19 in synchronization with a predetermined control signal, and supplies the signal to the input terminal of the separation circuit 27. It has become. Above DAC circuit 2
The multiplexed analog signal output from 6 is separated into two systems of analog signals corresponding to the analog signals of both the left and right channels by a separation circuit 27 that operates according to a predetermined control (g). There is.

The analog signals separated into the two systems are correspondingly outputted from a pair of output terminals of the separation circuit 27, and a pair of low-pass filters (LPF) 28.29 and 28.29, each having a cutoff frequency set to 20 kHz, are output from a pair of output terminals of the separation circuit 27. A pair of playback output terminals 0UTL, 0UTR and a monitor terminal (
Mr, ) and (MR) are supplied, respectively.

As a result, the sampled word recorded on the magnetic tape of the VTR 23 is transmitted to both the left and right channels of the audio output.
The signal is then restored to the original signal.

The device shown in FIG. 1, except for the VTRs 2 and 9, is generally referred to as a PCM 7' processor.

[Problems with background technology]

By the way, the apparatus shown in FIG. 1 has an EE (Electrical
ic to EAelectric) state, audio signals serving as monitor signals can be obtained from the monitor terminals (ML) and (MR), making it possible to monitor the recording signal.

However, in the device shown in FIG. 1, when the digital recording muting state is entered, the output of the recording processing circuit 21 becomes digital zero, and the outputs of the monitor terminals (ML) and (MR) cannot be obtained, and the output of the input terminal (INL) becomes zero. ) and (INR) could not be monitored. For this reason, it is extremely inconvenient when, for example, the apparatus shown in FIG. 1 is used to perform an air check on FM broadcasts.

On the other hand, when the recording signal is monitored at the input terminals (INL) and (INR), there is no change in the monitor sound even when the switch (S) is turned on, and the device shown in Figure 1 actually does not change. This poses a problem in that it becomes unclear whether or not the digital recording muting state is in effect.

[Summary of the invention]

The present invention provides a recording/playback device in which a recording system having a muting section and a playback system capable of monitoring the output of the recording system are each independently configured. first means for supplying the signal supplied to the input side of the muting section to the reproduction system in response to the operation of a switch;
The apparatus is characterized in that it comprises a monitor (second means for attenuating g to a predetermined level) output from the reproduction system.

[Purpose of the invention]

The present invention has been made in view of the above points, and is capable of continuously monitoring a recording signal even when the recording signal is muted in a recording/playback device equipped with an independent recording system and a playback system. It is an object of the present invention to provide an extremely good recording and reproducing device in which it is possible to recognize from a monitor signal whether or not a muting function is actually operating.

[Embodiments of the invention]

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 2 shows the configuration of a digital recording and reproducing apparatus which is a recording and reproducing apparatus according to the present invention. However, in FIG. 2, the same parts as in FIG. 1 are given the same reference numerals and their explanations will be omitted.

That is, the output terminal of the reproduction processing circuit 26 is connected to one input terminal (Ia) of the switching circuit 41. The output terminal of the ADC circuit 21 is connected to the other input terminal (rb) of the switching circuit 4. The switching circuit 4 is, for example, a well-known data selector (multiplexer), etc., and its output terminal is connected to the input terminal of the DAC circuit 26, and its control input terminal is connected to the control input terminal of the recording processing circuit 21 and the switch ( S) It is connected to the connection midpoint of one end. As a result, the switching circuit 41 switches to the switch (S).
The reproduction processing circuit 25 is supplied to the DAC circuit 26 when the switch (S) is off, and the AD
The output signal of the C circuit 20 is supplied to the DAC circuit 26.

On the other hand, each output terminal of the de-emphasis circuits 30 and 31 is connected to an output terminal (0UTL) and a monitor terminal (ML ) and the connection midpoints of the output terminal (0UTR) and monitor terminal (MR), respectively. Each of the attenuator circuits 42 and 43 has its control input terminal connected to the connection midpoint between the control input terminal of the recording processing circuit 21 and one end of the switch (S). and,
Each of the attenuator circuits 42 and 43 monitors the output signals of the de-emphasis circuits 30 and 31 through an output terminal (OUT), a monitor terminal (ML), and an output terminal (0UTR) when the switch (S) is in the OFF state. When the switch (S) is on, the output signals of the de-emphasis circuits 30 and 31 are respectively supplied to the output terminal (0UTL) and the monitor terminal (0UTL).
ML), output terminal (0UTR) and monitor terminal (MR
).

That is, in the apparatus configured as described above, when the recording state is set, if the switch (S) is off, the first
Similar to the device shown in the figure, the recording processing circuit 21 performs normal operation, and the output signal of the reproduction processing circuit 25 is supplied to the DAC circuit, and the de-emphasis circuit 42 and the
Each output signal of 3 is correspondingly supplied as a monitor signal to the monitor terminals (ML) and (MR), and the input terminal (INL
) and (INR) can be monitored.

On the other hand, when the switch (S) is turned on, the recording processing circuit 23 outputs a digital zero, and this signal is recorded on the VTR 23 via the video amplifier 22.

Further, in this state, the output signal of the ADC circuit 20 is supplied to the DAC circuit 26 via the switching circuit 41 and is converted into an analog signal. This signal is separated into two analog signals by the separation circuit 27, and each is sent to the LP.
F 28 and 29 correspondingly are supplied to de-emphasis circuits 30 and 31. The output signals of the de-emphasis circuits 30 and 31 are attenuated by corresponding predetermined levels by attenuator circuits 42 and 43, respectively, and sent to the respective monitor terminals (ML) and (MR) and output terminals (0UTL) and (0UTR). This is what is output.

As a result, the apparatus shown in FIG. 2 is advantageous in that it is possible to monitor the recording signal even if digital recording muting of the recording signal is performed in the recording state.

Furthermore, the recording signal level monitored when digital signal muting is performed is lower than when digital recording muting is not performed, so it is easy to recognize that digital recording muting is being performed. Very good condition.

Note that the present invention is not limited to the above-mentioned embodiments, and can be applied to, for example, a digital recording/reproducing apparatus that performs mini-neating of recorded signals in an analog manner. The present invention can also be applied to recording/playback devices in which the recording system and playback system are independent, such as the analog cheap recorder.

It goes without saying that various other modifications and applications are possible without departing from the gist of the invention.

〔Effect of the invention〕

As described in detail above, according to the present invention, in a recording apparatus equipped with an independent recording system and a playback system, it is possible to continue monitoring the recording signal even when the recording signal is muted, and 1. It is possible to provide an extremely good recording and reproducing device in which it is possible to recognize from a monitor signal whether or not the muting function is actually operating.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a conventional recording/playback device.
FIG. 2 is a block diagram showing an embodiment of the recording/playback device according to the present invention. 11.12...Amplifier, 13.14...Pre-emphasis circuit, 15.16...LPF, 17.18...
S/H circuit, 19...Mixing circuit, 20...ADC circuit, 21...Recording processing circuit, 22...Video amplifier, 23...VTR, 24...Synchronizing signal separation circuit, 2
5... Reproduction processing circuit, 26... DAC circuit, 27.
...Separation circuit, 28.29...LPF, 30.31.
...De-emphasis circuit, 41...Switching circuit, 42゜43...Attenuator circuit, S...Switch, INL +INR...Input terminal, 0UTL,
0UTR...output terminal, ML, MR...monitor terminal.

Claims (1)

[Claims] In a recording/playback device that includes a recording system having a muting section and a playback system capable of monitoring the output of the recording system, each of which is configured independently, the present invention provides a method for operating a muting switch that drives the muting section in a recording state. and a second means for attenuating a monitor signal output by the reproduction system to a predetermined level. A recording/playback device characterized by: