Abstract: A radio relay communication system wherein a signal transmitted from active one of a plurality of radio units is received and recorded. When the transmission operation of the particular radio unit stops, the recorded signal is reproduced and transmitted by a relay unit, and another radio unit receives the signal from the relay unit. A relay start signal is transmitted from the first radio unit. and is received by the relay unit. In response to the relay start signal, the relay unit generates a sync signal of predetermined period. The first radio unit, in accordance with the reception of the sync signal, transmits an input signal as compressed to less than one half along the time axis. The relay unit alternates between the period of receiving the compressed signal and the period of transmission in synchronism with the sync signal.

Abstract: In radio communication system in which single frequency simultaneous transmission and reception is performed, a speech audio signal is divided by a predetermined time interval. A transmission time and a reception time are allotted in the predetermined time. A time-compressed signal is transmitted during the transmission time, and a time-compressed signal transmitted from other transceiver is received during the reception time and it is decompressed to the original length. The transmission time and the reception time are alternately repeated to transmit and receive the audio signals substantially simultaneously by a single frequency, and the audio signal is reproduced from the received signal. When communication with a telephone set is to be established, a DTMF signal is used as a dialing signal to call the telephone set from the transceiver. The DTMF signal is time-compressed and then transmitted along with the speech signal.

Abstract: A transceiver having a transmitting unit and a receiving unit for performing substantially simultaneous communication with another transceiver in both directions by using a single frequency carrier. The transceiver includes a unit for generating a synchronizing signal for alternately switching between a transmission time period and a reception time period of the transceiver at a predetermined period, a signal processing unit for converting an input signal into a compressed signal by compressing a time axis of the input signal by a predetermined ratio, and affixing the synchronizing signal to the compressed signal, a unit for supplying the compressed signal with the synchronizing signal to the transmitting unit during the transmission time period, and a unit for reproducing an original signal from a signal transmitted from the other transceiver and received by the receiving unit during the reception time period, by expanding a time axis of the signal by a predetermined ratio.

Abstract: A radio apparatus having a unit for receiving a first signal from a first transceiver compressed in time by a predetermined rate, a unit for reproducing a first original signal from the first signal, a unit for receiving a second signal from a second transceiver compressed by the predetermined rate during the reception period of the first transceiver, a unit for reproducing a second original signal from the second signal, and a unit for adding the first and second original signals and outputting the added signal.

Abstract: A duplex voice communication radio transmitter-receiver according to the present invention is provided with a low-pass filter arranged before a time compressing device in a transmitter section for cutting off a higher frequency portion of the band of a voice signal thus to decreasing the maximum modulation frequency of the same to less than a half so that it can be operated with the use of an assigned, single frequency transmission radio wave of which frequency band is legally limited, improved in the utilization of frequencies, minimized in the delay of communication signals, and enhanced in the articulation and intelligibility of a reproduced voice sound.

Abstract: A voice transmission method and apparatus in a duplex radio system are disclosed in which a voice signal to be transmitted in a constant period of time is subjected to 1/N time compression, N being a numeral not smaller than 2.0. The time-compressed voice signal is supplied to a transmitter as a modulating signal and a transmitting operation is performed by the transmitter in synchronism with a period of time when the modulating signal is inputted to the transmitter. A receiving operation of receiving a time-compressed and modulated signal transmitted from the transmitter to demodulate it is performed by a receiver in a period of time other than the period of time when the transmitting operation is performed. A demodulated signal is subjected to N-ple time expansion to obtain a reproduced receive voice signal, and both the transmitting operation and the receiving operation are repeated at the constant period of time.