Abstract: The present invention relates to a radio communication system that provides a transmission technique capable of suppressing degradation of communication quality even in an area other than an interference area of two base station radio waves. Further, the transmission technique and the communication system include implementation of a Differential Space-Time Block Coding (DSTBC) method relating to transmission diversity in radio communication utilizing, for example, base stations with transmission antennas that transmit respective sequence signals of the DSTBC.

Abstract: A radio communication system that provides a transmission technique capable of suppressing degradation of communication quality even in an area other than an interference area of two base station radio waves.

Abstract: An engine valve forging system includes a molding forging die having a circular hole stem molding portion continued to a tip end of a head type molding portion, to mold an engine valve by extrusion-forging a material from the head type molding portion to the stem molding portion by an upper die, and a stem guide forging die which is coaxially disposed to communicate with a tip end of the stem molding portion, and has a guide portion for a stem portion of an engine valve extruded from the stem molding portion, and a plurality of stem curve restraining portions having a shape gradually tapering toward a central shaft line from a rear end portion to a tip end portion are formed continuously along the central shaft line of the guide portion in the guide portion, to be capable of manufacturing high-precision engine valves with less stem curve.

Abstract: Provided is a transmitter for transmitting signals by means of the STBC method or the DSTBC method, wherein communication is carried out effectively. The transmitter for transmitting signals by means of the STBC method or the DSTBC method has the following configuration. A frame in which synchronization words are arranged at specified positions is used. An encoding means in the transmitter encodes the entire frame to be transmitted including the synchronization words, by means of the STBC method or the DSTBC method. It is also possible to implement a communication system and a communication method for communicating signals by means of the STBC method or the DSTBC method.

Abstract: An engine valve forging system includes a molding forging die having a circular hole stem molding portion continued to a tip end of a head type molding portion, to mold an engine valve by extrusion-forging a material from the head type molding portion to the stem molding portion by an upper die, and a stem guide forging die which is coaxially disposed to communicate with a tip end of the stem molding portion, and has a guide portion for a stem portion of an engine valve extruded from the stem molding portion, and a plurality of stem curve restraining portions having a shape gradually tapering toward a central shaft line from a rear end portion to a tip end portion are formed continuously along the central shaft line of the guide portion in the guide portion, to be capable of manufacturing high-precision engine valves with less stem curve.

Abstract: In a transmitter which transmits a signal by a DSTBC scheme, communication is efficiently performed by the DSTBC scheme. In the transmitter which transmits the signal by the DSTBC scheme, a frame in which a sync word is disposed in a predetermined position subsequent to the head is used. Initial value controller (31 to 35) sets initial values of differential encoding (differential encoding unit 15) when a DSTBC encoder which processes a transmission target processes the frame on the basis of values from the head of the frame to a position before the sync word so that a signal point corresponding to the position immediately before the sync word in the DSTBC encoder which processes the transmission target becomes a specific point.

Abstract: In a transmitter, communication is efficiently performed by a DSTBC scheme. In a transmitter which transmits a signal using the DSTBC scheme, the content of a transmission process is set so that a state where a symbol is not present is realized at the origin of signal arrangement in a DSTBC encoder. As an example, the setting is performed so that an input to the DSTBC encoder is calculated using a predetermined operation in which a state where a symbol is not present is realized at the origin of signal arrangement in the DSTBC encoder. As another example, the setting is performed so that initial values in which a state where a symbol is not present is realized at the origin of signal arrangement in the DSTBC encoder are used in differential encoding of the DSTBC encoder.

Abstract: Provided is a transmitter for transmitting signals by means of the STBC method or the DSTBC method, wherein communication is carried out effectively. The transmitter for transmitting signals by means of the STBC method or the DSTBC method has the following configuration. A frame in which synchronization words are arranged at specified positions is used. An encoding means in the transmitter encodes the entire frame to be transmitted including the synchronization words, by means of the STBC method or the DSTBC method. It is also possible to implement a communication system and a communication method for communicating signals by means of the STBC method or the DSTBC method.

Abstract: In a transmitter which transmits a signal by a DSTBC scheme, communication is efficiently performed by the DSTBC scheme. In the transmitter which transmits the signal by the DSTBC scheme, a frame in which a sync word is disposed in a predetermined position subsequent to the head is used. Initial value control means 31 to 35 set initial values of differential encoding (differential encoding unit 15) when a DSTBC encoder which processes a transmission target processes the frame on the basis of values from the head of the frame to a position before the sync word so that a signal point corresponding to the position immediately before the sync word in the DSTBC encoder which processes the transmission target becomes a specific point.

Abstract: In a transmitter, communication is efficiently performed by a DSTBC scheme. In a transmitter which transmits a signal using the DSTBC scheme, the content of a transmission process is set so that a state where a symbol is not present is realized at the origin of signal arrangement in a DSTBC encoder. As an example, the setting is performed so that an input to the DSTBC encoder is calculated using a predetermined operation in which a state where a symbol is not present is realized at the origin of signal arrangement in the DSTBC encoder. As another example, the setting is performed so that initial values in which a state where a symbol is not present is realized at the origin of signal arrangement in the DSTBC encoder are used in differential encoding of the DSTBC encoder.