摘要:
A digital signal magnetic recording/reproducing apparatus modulates a digital signal with a carrier and performs recording/reproducing of the modulated signal. The carrier frequency is made equal to the clock frequency multiplied by a factor (N/M), where N and M are integers. The carrier and clock are reproduced using only one phase locked loop. When the carrier-modulated signal is recorded/reproduced using a magnetic recording medium, the phase of the modulated signal is shifted relative to the phase of the carrier. Shifting the clock phase before using the clock for decoding the demodulated signal prevents a degradation of error rate. By periodically inserting a clock phase reference signal in the recording signal, accuracy of adjustment of clock phase is improved.
摘要:
A digital signal magnetic recording/reproducing apparatus converts a digital signal into multi-value digital signals and performs recording/reproducing of a multi-value quadrature amplitude-modulated signal. By using the multi-value quadrature amplitude modulation, it is possible to remove the DC component in the recording signal and improve the utilization efficiency of the recording frequency band. Further, using a system to memorize the frequency characteristic of the magnetic recording/reproducing unit and effect Viterbi decoding regarding the intersymbol interference caused by the frequency as a convolutional coding, it is possible to detect the level without necessitating frequency equalization. Accordingly, there arises no deterioration of the S/N ratio by frequency equalization. Furthermore, by providing an encoder for error control coding by increasing the number of multi-values and a corresponding decoder, the error rate can be improved against the deterioration of the S/N ratio. Further, by bias recording the multi-value quadrature amplitude modulated signal, non-linearity of the electromagnetic conversion system is relaxed, and deterioration of the S/N ratio by distortion is improved.
摘要:
A digital signal magnetic recording/reproducing apparatus converts a digital signal into a multi-value digital signal, followed by recording/reproducing the quadrature biphase modulated multi-value quadrature amplitude modulated signal. By using a multi-value quadrature amplitude modulation, a direct current component in the recorded signal can be eliminated, and the utilization efficiency of the recording frequency band of the digital signal magnetic recording/reproducing apparatus can be improved. Also, with respect to the amplitude non-linear characteristic which occurs in the magnetic recording/reproducing process, by providing a compensating circuit during the mapping before recording or after reproducing and demodulating, the deterioration of the S/N ratio of the reproduced and demodulated signal can be reduced to decrease the errors in the decoded data. Furthermore by bias-recording the multi-value quadrature amplitude modulation signal, the non-linearity of the electromagnetic conversion system is alleviated to decrease the deterioration of the S/N ratio due to distortion, thereby making the application of the modulation scheme more reliable.
摘要:
A digital signal magnetic recording and playback apparatus which is applicable to digital video signals, utilizes quadrature amplitude modulation to produce a recording signal from a digital input signal with a carrier frequency being employed which is less than or equal to than the frequency of a recording system clock signal that is synchronized with the successive data values of the digital input signal. Carrier bursts are periodically inserted into the recording signal with a fixed period, through data inserted by a burst data insertion circuit and the carrier and clock signal are arranged to periodically coincide in phase, with the aforementioned period. The carrier frequency is made equal to the clock frequency multiplied by a factor (n/m), where n and m are integers and n
摘要:
A digital signal magnetic recording/reproducing apparatus converts a digital signal into a multi-value quadrature amplitude modulated signal, and records and reproduces the multi-value quadrature amplitude modulated signal. By using the multi-value quadrture amplitude modulation, any DC component in the recording signal is removed and utilization efficiency of the recording frequency band can be improved. By bias recording of the multi-value quadrature amplitude modulated signal, non-linearity of the electromagnetic of conversion system is reduced, and deterioration of SN ratio due to distortion is improved.
摘要:
An FM signal demodulator has a phase shifter including transversal filters for producing from a FM video signal two FM video signals which are different in phase by 90.degree. from each other, and a demodulator for detecting phase information of the FM video signal, wherein the carrier frequency is at least quadrupled prior to demodulation so as to suppress components of the FM video signal not to be included in the demodulated video signal.
摘要:
By transforming a duobinary signal, a value of -1 cannot appear again after a value of zero following -1 as shown in a string of -1.fwdarw.0.fwdarw.-1 and a value of 1 cannot appear again after a value of zero following 1 as shown in a string of 1.fwdarw.0.fwdarw.1. Narrow-band transmission is made possible by the fact that the direct current (DC) component of a duobinary signal can be eliminated and reproducible original information can be recorded by discriminating its even level as a one (1) and its odd level as zero (0). Since the DC component can be eliminated, electromagnetic conversion systems are subjected to less distortion, leading to a reduction in the probability of coding errors.
摘要:
A video signal reproduction apparatus for reproducing a composite color video signal from a recording medium. A signal reproduced from the recording medium is divided into a frequency-modulated (FM) signal and a low-band-converted signal by filters. The FM signal is demodulated by a demodulater into a luminance signal. A first conversion circuit produces from the low-band-converted signal a chrominance signal without a phase jitter component. A second conversion circuit produces from the low-band-converted signal a high-band component of luminance signal with a same phase jitter component as that of the luminance signal obtained from the demodulator. The luminance signal from the demodulator, the high-band component of luminance signal and the chrominance signal are mixed to obtain the composite color video signal.
摘要:
At least three heads are mounted on a rotary drum. Between the first and third heads which are located in close proximity to each other and have different azimuth angles, a minute height difference is formed in the rotation shaft direction of the rotary drum. Signals of a plurality of data rates are recorded and reproduced by using the first and second heads or the first and third heads. Two heads having the same azimuth angle are disposed on the rotary drum so as to be opposed each other at a central angle of 180°. In search speed reproduction, search data are reproduced by the two heads. Tracks are divided in the unit of plural tracks so as to form track sets. Search data areas of each track set are disposed at a position of each track which is separated from the edge of a tape by a predetermined distance. In search speed reproduction, the phases of the tracks and the heads are controlled, and all effective data of the search data areas are reproduced by plural scans of the heads.
摘要:
A fuel cell body has an anode having an anode-side separator with projections and depressions formed on its surface, a cathode, and a membrane electrode assembly disposed between the anode and the cathode, and the fuel cell body is disposed in a container for storing liquid fuel so that at least the anode side is immersed therein. Fuel passageways through which the liquid fuel flows are formed by regions surrounded by the projections and depressions on the surface of the separator and the membrane electrode assembly. By this, the downsized, simplified and lower power consuming structure of auxiliary equipment such as a fuel feed system is achieved.