| 摘要 |
PROBLEM TO BE SOLVED: To realize multi-party speech with a comparatively simple circuit configuration and use of only one slot by providing a means switching a reception/transmission timing with respect to call reception from a radio telephone set or the like. SOLUTION: A synchronization section 6 is provided with a transmission reception timing changeover means selecting a reception/transmission timing with respect to call reception from a plurality of other radio telephone sets taking part in a speech, a speech section 5 is provided with a voice decoding means that distinguish received calls from a plurality of the other radio telephone sets and decodes them to each radio telephone set and with a reception synthesis means adding and synthesizing the outputs of the means, and a control section 7 is provided with a coding rate revision means revising a coding sampling frequency for a transmission signal inversely proportional to the number of the radio telephone sets. Then a TDMA/TDD control section 4 extracts its own slot signal from a digital signal subject to π/4 shift QPSK demodulation, the speech section 5 conducts ADPC demodulation and PCM demodulation to demodulate a voice signal and the result is outputted from a speaker 11 being a receiver. |
