PURPOSE:To prevent the reduction of an audio signal band accompanied with the reduction of the number of samples by supplying a clock signal having a frequency corresponding to the transmission rate of reproducing data to a reproducing circuit to change properly the passing band of an LPF. CONSTITUTION:A disc 1 is rotated by control data which is recorded on the ditgital disc 1 together with audio and video digital data and indicates the linear speed of the disc 1 at a reproducing time. Simultaneously with this rotation, the clock signal having a frequency corresponding to the transmission rate of reproducing data is supplied to a reproducing circuit 4, and reproduced audio data of the circuit 4 is subjected to D/A conversion to adapt the passing band of an LPF12, to which this reproduced analog signal is supplied, to the band of the reproduced analog audio signal. As the result, the problem of the reduction of the transmission band due to lack of the number of samples of audio data for reproducing is resolved.

Reproducing device of digital disc

PURPOSE:To unify the recording waveform and the recording format on a recording medium by changing the feed speed of the recording medium in proportion to a transmission rate when recording a PCM digital signal obtained by defining a common multiple of the two different quantized number of bits as the PCM data bit number of a frame. CONSTITUTION:A sample of 16 bits is divided into symbols of upper and lower 8 bits each while the sample data of 16 bits and 12 bits of the different quantized number of bits are divided into symbols. While 12 bits of a sample are divided into high-order 8 bits and low-order 4 bits and added with low-order 4 bits of another sample to form a symbol. Thus the number of symbols is set at 24 for each track by said division of symbols. Therefore the sample number of each track forms a data of 12 samples with quantization of 16 bits, and a data of 16 samples with quantization of 12 bits, respectively. A feed speed control circuit 103 for recording medium 7 changes the feed speed of the medium 7 in proportion to the transmission rate of a PCM digital signal.

Fixed head type digital signal recording and reproducing device

PURPOSE:To select sampling frequency and the number of quantitizing bits, by constituting so that the sampling frequency of an A/D converter and the number of quantitizing bits can be set optionally in accordance with the purpose respectively, by swtiching the clock frequency. CONSTITUTION:In case when a switch 29 is connected to T1, a master clock from a master clock generating part 27 is inputted to a various clock generating part 30. In this case, a clock signal outputted to each part, from the various clock generating part 30 is constituted so as to attain 50.4kHz as sampling frequency and 307.2kHz as data frequency of a recording signal. Subsequently, when the switch 29 is connected to T2, the master clock inputted to the various clock generating part 30 attains a signal whose frequency is divided into two. As a result, various clock signals outputted from the various clock generating part 30 all attain signals whose frequency is divided into two.

Pulse code modulation recording and reproducing device

PURPOSE:To use a digital matrix circuit for various synthesis signal in common, by obtaining plural kinds of synthesized chrominance signals at a digital matrix circuit and attaining multi-function of the digital matrix circuit. CONSTITUTION:A blue ER signal is applied to a signal input terminal 11, a blue EB is applied to a signal input terminal 12, a green EG signal is applied to a signal input terminal 13 and the operation of switch circuits 131-133 is designated with an external control signal CTL of logical ''0''. Then, a ctrominance E1 signal of the NTSC system is obtained at a signal output terminal 15. The EG signal is applied to the terminal 11, the EB signal is applied to the terminal 12 and the signal ER is applied to the terminal 13 and the operation of the switch circuits 131-133 is designated with the CTL being logical ''1'', allowing to obtain a color EQ signal of the NTSC system at the terminal 15. Thus, the E1 or EQ signal of the NTSC system is designated and outputted with the CTL selectively. Thus, the digital matrix circuit 10 is circuit-integrated for a common component for the E1 and EQ signals.

Digital matrix circuit

PURPOSE: To select the optimum sampling speed corresponding to the characteristic of an analog signal to record by separately decoding the scheduled message part of an audio data and reproducing it with the freely selectable part of video data. CONSTITUTION: One block of video coding data or audio coding data is made to respond to a command signal from a command line 16 and a control circuit 28 reads it from RAM 50. After that, the block is made to respond to another command signal of the line 16 to retrieve a selected message pointer to process this, to obtain the address of the first 8-bit of a related message unit and the sampling speed of this data unit. After that, a part corresponding to the entire selected audio message unit among audio data is retrieved from RAM 50 to be sent to an adaptive type delta demodulator 64, to be demodulated here to data of an audio message unit to be output from a line 68.

Optical disk and regenerating device thereof

PURPOSE:To enable to select the recording time and audio quality freely, by changing the sampling frequency according to the amount of information recordable at the change-over of tape speed. CONSTITUTION:The tape running speed variable circuit is constituted with the master clock generating circuit 31, frequency dividing circuit 30, servo circuit 29, and capstan motor 28. The master clock suitably frequency-divided at the circuit 30 is fed to the sample hold circuits 5, 6 and time axis conversion circuit 11. When the bit rate of recording signal is kept as it is and the running speed is made slow, the recording wave length lambda is smaller. Then, the bit rate is lowered to obtain excellent output. Accordingly, when the tape speed is halved, the clock is halved at the clock recording. When the master clock is selected with the switch SW1, the interlocked SW2 is also operated and the cut-off frequency of LPF is switched. Thus, since the tape speed, sampling frequency, and recording clock can be changed by only changing the master clock, the recording time and sound quality can be selected.

Shimizu Tetsuo

Papers

Recording and reproducing unit of pcm system