摘要:
A speech coding transmission system is disclosed in which a coder of a differential coding system quantizes a difference between a predictive value from an adaptive predictor and an input speech signal by an adaptive quantizer in accordance with the level of the latter and to send out the resulting coded signal to transmission medium, and a decoder outputs a reproduced speech signal on the basis of a residual signal obtained by inversely quantizing a received coded signal with an inverse adaptive quantizer and a predictive value from an adaptive predictor. Both or either one of the coder and the decoder includes a comparator-attenuator which attenuates the amplitude of the input signal or reproduced speech signal to a value smaller than a predetermined threshold value and applies to the amplitude-attenuated speech signal to the adaptive predictor.
摘要:
A voice coding communication system in case of applying an adaptive differential PCM system in which a discontinuous transmitter is provided at the transmitting side to reduce its power consumption, transmission is suspended during a silent duration, and a pseudo-noise is generated at the receiving side and is used as the reproduced output during the silent duration. Discomfort is avoided in hearing the reproduced voice which is caused by the difference between the level of the pseudo-noise and the level of a background noise at the transmitting side.
摘要:
A speech coding circuit is disclosed, which comprises a PCM encoder for converting an analog input into a digital output, and a speech coder with voice activity detector which encodes the digital output from the PCM encoder into speech coding data and detects whether the analog input is voice active or non-active, for each period, and then outputs a speech detection flag indicating whether the analog input is voice active or non-active. A power comparator compares the power of the analog input with a predetermined power threshold value and outputs a level detection flag indicating voice activity or non-activity, depending on whether the power of the analog input is greater or smaller than the power threshold value. A mode switch receives the level detection flag indicating voice activity or non-activity and applies to the PCM encoder and the speech coder a mode control signal which puts them into an activated mode or a sleep mode.
摘要:
Apparatus, and an associated method, for a radio communication system. Asymmetrically positioned downlink data transmitting stations and uplink data receiving stations are positioned defining downlink service areas and uplink service areas. A mobile terminal, when positioned in the downlink service area, is able to receive high speed downlink data. And, when the mobile terminal is stationed within an uplink service area, the mobile terminal is capable of sending data at high data rates to an uplink receiving station.
摘要:
Like a conventional one-way pager system, a two-way pager system is provided in which a message is received by paging from a base station and a message responding to the received message is returned to the base station. In this system, direct communication and peer-to-peer communication between terminals are performed. All the terminals included in the service area of the base station are always synchronized with sync signals paged from the base station. No special infrastructure is therefore required for synchronizing the terminals with the sync signals to perform the peer-to-peer communication. Furthermore, since each of the terminals receives a paging signal during the peer-to-peer communication, it can respond to a paging call.
摘要:
Like a conventional one-way pager system, a two-way pager system is provided in which a message is received by paging from a base station and a message responding to the received message is returned to the base station. In this system, direct communication and peer-to-peer communication between terminals are performed. All the terminals included in the service area of the base station are always synchronized with sync signals paged from the base station. No special infrastructure is therefore required for synchronizing the terminals with the sync signals to perform the peer-to-peer communication. Furthermore, since each of the terminals receives a paging signal during the peer-to-peer communication, it can respond to a paging call.
摘要:
A method for fabricating semiconductor devices wherein polysilicon gates for complementary-type field-effect semiconductor devices are formed of polysilicon to which impurity doped simultaneously to the polysilicon deposition; the both gates having the dual N.sup.+ /P.sup.+ polysilicon gate structure, so that the both N- and P-channel transistors are formed as the surface-channel type ones; and therefore, the off-characteristic, the short channel effect, and the controllability of threshold voltage are progressed. More specifically, N- and P-channel MISFETs are provided on a common semiconductor substrate (1); N-type polysilicon (9) doped with N-type impurity is adopted as the gate electrode for the N-channel MISFET; P-type polysilicon (8) doped with P-type impurity is adopted as the gate electrode for the P-channel MISFET; and a narrow region preventing the mutual diffusion of impurities is provided between portions of respective polysilicon.
摘要:
A spreading process is performed with a spreading code assigned to each user and a spreading code assigned according to an attribute, and the resultant signal is modulated on the transmitter side. On the receiver side, a transmitted signal, modulated in the above manner, is subjected to a despreading process with the attribute-oriented spreading code from a reception spreading code generator, the resultant signal is subjected to despreading process with the user-specific spreading code from the reception spreading code generator, and those signals which have undergone the despreading processes are demodulated by data demodulators to extract desired information together with a desired signal corresponding to a wide band service. It is therefore possible to simplify the management of the individual users and individual services and facilitate the system design.
摘要:
Apparatus, and an associated method, for a radio communication system. Asymmetrically positioned downlink data transmitting stations and uplink data receiving stations are positioned defining downlink service areas and uplink service areas. A mobile terminal, when positioned in the downlink service area, is able to receive high speed downlink data. And, when the mobile terminal is stationed within an uplink service area, the mobile terminal is capable of sending data at high data rates to an uplink receiving station.
摘要:
An information terminal transmits small amount data such as a command to a Web server on the internet to an asymmetric router via an interactive radio network. The asymmetric router transmits the command to the Web server via the internet. The asymmetric router transmits large amount data (for example, HTML formatted browser data) from the Web server to a data superimposing broadcast apparatus. The data superimposing broadcast apparatus determines a scheduled time of broadcasting according to a data amount. The scheduled time is transmitted to the information terminal via the asymmetric router and the interactive radio network. When the scheduled time comes, the large amount data is superimposed on an empty portion of a television signal, and is broadcasted. The information terminal carries out a predetermined processing operation whereby a broadcast receiving circuit is turned on, and the television signal on which the large amount data has been superimposed is received. The received data then can be displayed in a display device and the like. Therefore, even in a portable information terminal, it is possible to provide an interactive communication system which can transmit large amount data at a high speed.