Abstract: In one aspect, a machine tool having a frame assembly, a first head having a first rotatable workpiece holder, and a second head having a second rotatable workpiece holder. The frame assembly includes a first door movable in a first direction between a first closed position and a first open position and a second door movable in a second direction transverse to the first direction between a second closed position and a second open position. The frame assembly has an access opening sized to permit access to the first and second heads with the first door in the first open position and the second door in the second closed position. The frame assembly has a larger access opening to increase ease of user accessibility to the first and second heads with the first door in the first open position and the second door in the second open position.

Abstract: An apparatus for receiving digital data includes a memory unit for temporarily storing therein a plurality of data streams, each of which includes data and clock obtained by demodulating plural redundant signals received in each receiver in response to a signal generated based on each clock; a writing control unit for controlling a writing of the plurality of the data streams into the memory unit; a data reading control unit for reading the data streams stored temporarily in the memory unit in a synchronized manner; and a selection unit for selecting one of the read data streams to output the selected data stream. The writing control unit detects a synchronization packet included in the plurality of data streams to control the writing of the plurality of data streams into the memory unit based on the synchronization packet.

Abstract: A received, same signal is distributed to two channels, the received signals on the two channels are demodulated to produce a plurality of data streams on each of the two channels, and the plurality of data streams of one channel is selected to produce from the pluralities of data streams on the two channels.

Abstract: A distortion compensating circuit for a power amplifier attains raised compensating accuracy with shorter convergence time by accurately and quickly generating a distortion compensation signal for pre-distortion. An error signal representing the difference between the input and output signals of the power amplifier is generated. From the error signal and the input signal, the coefficients of the third-order intermodulation distortion, fifth-order intermodulation distortion and seventh-order intermodulation distortion are calculated. According to these coefficients, a distortion compensating signal which is characteristically opposite in phase and gain to the intermodulation distortions is generated.

Abstract: An apparatus for receiving digital data includes a memory unit for temporarily storing therein a plurality of data streams, each of which includes data and clock obtained by demodulating plural redundant signals received in each receiver in response to a signal generated based on each clock; a writing control unit for controlling a writing of the plurality of the data streams into the memory unit; a data reading control unit for reading the data streams stored temporarily in the memory unit in a synchronized manner; and a selection unit for selecting one of the read data streams to output the selected data stream. The writing control unit detects a synchronization packet included in the plurality of data streams to control the writing of the plurality of data streams into the memory unit based on the synchronization packet.

Abstract: A data transmission system and method utilizing orthogonal frequency division multiplexing, wherein in a receiver apparatus of the data transmission system, synchronization is obtained by the following steps. A correlation value of a reception signal which was orthogonal frequency division multiplexed and a predetermined sync symbol pattern or a signal obtained by delaying one effective symbol period is arithmetically calculated a predetermined times in a predetermined arithmetic calculation window. The correlation values obtained after a predetermined number of arithmetic calculations from an intermediate of a total number of the arithmetic calculations are reduced so as to not exceed a predetermined value. The maximum value is detected from the correlation values and a reference signal for demodulating the reception signal is formed based on information of a time based position of a signal at the time when the maximum value is obtained.

Abstract: A distortion compensating circuit for a power amplifier attains raised compensating accuracy with shorter convergence time by accurately and quickly generating a distortion compensation signal for pre-distortion. An error signal representing the difference between the input and output signals of the power amplifier is generated. From the error signal and the input signal, the coefficients of the third-order intermodulation distortion, fifth-order intermodulation distortion and seventh-order intermodulation distortion are calculated. According to these coefficients, a distortion compensating signal which is characteristically opposite in phase and gain to the intermodulation distortions is generated.

Abstract: A data transmission system for transmitting data from a transmitter to a receiver located away therefrom. The transmitter includes circuitry for transmitting together a main signal having a carrier modulated with main data to be transmitted and as well as a sub-signal to be used in frequency conversion and generated by modulating a carrier of a predetermined frequency out of a frequency band of the main signal. The receiver includes circuitry for receiving a receive signal from the transmitter and extracting the sub-signal therefrom and also includes circuitry for generating a signal to be used as a reference at the time of converting the receive signal to a signal having a predetermined frequency on the basis of the extracted sub-signal.

Abstract: A received, same signal is distributed to two channels, the received signals on the two channels are demodulated to produce a plurality of data streams on each of the two channels, and the plurality of data streams of one channel is selected to produce from the pluralities of data streams on the two channels.

Abstract: A communication method in an orthogonal frequency division multiplexing modulation communication system includes a transmission apparatus in which a frequency bandwidth of a signal modulated in accordance with an orthogonal frequency division multiplexing modulation system is changed and the modulated signal is transmitted and a receiving apparatus in which the modulated signal is received and a frequency bandwidth for demodulation of the received signal is changed to follow the change of the frequency bandwidth of the modulated signal.

Abstract: A data transmitting apparatus in which in an antenna switching of the data transmitting apparatus, a sudden change of transmission path characteristics is prevented and a state where an automatic equalizing function on the reception side can follow can be held. The apparatus has a processing circuit for gradually switching antennas of the data transmitting apparatus with respect to the time and for continuously switching one antenna from the rated level to the 0 level and for continuously switching the other antenna from the 0 level to the rated level. The apparatus operates so as to always keep the optimum constellation state in which the automatic equalizing process follows.

Abstract: A data transmission apparatus of an orthogonal frequency multiplex modulation system wherein data is transmitted using a plurality of carriers which are in a mutually orthogonal relationship with one another. The apparatus includes a transmitter which previously inserts a group of predetermined synchronization symbols into an OFDM modulated transmission signal every fixed period and a receiver which demodulates a received OFDM modulated transmission signal to a baseband OFDM signal. In the receiver, an absolute value of an A/D converted digital signal is taken and the signal is bandwidth-limited to a predetermined band width. Then, it is decided whether an amplitude of the signal is larger than or smaller than a predetermined value and a decision result thereof is produced. A null section in the synchronization symbol group is detected on the basis of the decision result and a start point of another synchronization symbol subsequent to the null section is further detected.

Abstract: An orthogonal frequency division multiplex (OFDM) modulator of such a system as to add guard intervals to a temporal waveform generated by modulating an input data train into a large number of (sub)carriers, conducting quadrature modulation, and outputting an OFDM signal.

Abstract: A data transmission apparatus using a digital modulation system wherein a transmitting side inserts a group of predetermined synchronization symbols into a transmission signal at predetermined intervals to be transmitted. A receiving side calculates an electric power value of a received transmission signal. When a no-signal period (null section) in the synchronization symbol group is to be detected and decided from a magnitude of the received signal electric power value, a threshold for reference of decision for detecting the null section is calculated on the basis of an average electric power value for a predetermined period in the received signal electric power value and the threshold calculated in accordance with the received signal level of the transmission signal is used to detect synchronization stably.

Abstract: In a demodulating method of demodulating amplitude-demodulated signals in an amplitude phase shift keying system for conducting an amplitude modulation by setting signal points as information codes on a complex plane representing a signal space of transmission signals onto circumferences of two concentric circles including a first circle having a first diameter and a second circle having a second diameter smaller than the first diameter on the complex plane, there are obtained, in accordance with an amplitude value of an amplitude component of each symbol of a received amplitude-modulated signal, a first threshold value and a second threshold value having a predetermined relationship with the amplitude value.

Abstract: An image signal compression transmission system for transmitting and receiving a compressed image signal, having a transmitter section which entropy codes digitized image data for transmission, a transmission channel through which entropy-coded codes sent from said transmitter section are transmitted, and a receiver section which decodes said entropy-coded codes received from said transmission channel and derives an original digital image signal. In the transmitter section, digital image data is entropy coded. The entropy-coded codes are transmitted to the receiver section through the transmission channel. In the receiver section, the received codes are entropy code decoded at a decoding speed corresponding to a transmission rate on the transmission channel. Coefficient codes derived by the decoding are stored into a memory at the same speed as the decoding speed.

Abstract: A coating composition for solar selective absorption comprising, in solvent, particles of an inorganic black pigment dispersed in a dissolved binder of a thermosetting acrylic resin and particles of a low molecular weight fluorocarbon resin contained in an amount of 5-15 parts by weight per 100 parts by weight of the acrylic resin. The inorganic black particles have a size of 0.01-0.5 microns and are contained in an amount of 45-65 parts by weight per 100 parts by weight of the acrylic resin. An article having a metal substrate and a paint film formed thereon from the composition in a dry thickness of 1.5 microns or more is also described.

Abstract: Method for removal of carbon monoxide from air wherein air to be purified is passed through a catalyst for promotion of oxidation of carbon monoxide consisting of a carrier including powdered activated carbon, an alkali, and a bonding agent and inpregnated with palladium alone or in combination one or more of the elements ruthenium, rhodium, and platinum. The amount of included alkali is made such that there is reduced risk of combustion due to presence of activated carbon, and the bonding agent renders the catalyst more resistant to vibration, while high rates of carbon removal are achieved at comparatively low temperature and high rates of air flow through the catalyst.