JPS6462927A - Mobile body data transmitter-receiver - Google Patents

Abstract

PURPOSE:To attain the communication by frequencies of minimum kinds at a weak electric field, by allowing a master station to call a slave station periodically by a 1st carrier including a specific number, to receive and demodulate a 2nd carrier being an acknowledge from the slave station, sending the signal for prescribed number of times in detecting any error and storing the reply when no error exists. CONSTITUTION:A CPU 10 of a master station 111 sends periodically a data of a specific number of a slave station 2A and an error check bit from a transmitter 11 to plural slave stations 2A (in figure only one station is shown) in a frequency f1 according to the built-in program. The receiver 21 of the slave station 2A receives the carrier f1 and demodulates it and gives the result to a CPU 20 and when it is checked that there is no error and the data specific to itself is detected, the receiver 22 checks that the other slave station does not send the 2nd carrier f2. When the other slave station does not send the carrier f2, the carrier f2 is sent to the master station from the transmitter 23 of its own station. The master station 111 uses the receiver 12 to receive the carrier f2 and when any error is detected, the signal is sent to the same slave station for plural number of times. When no error exists, the demodulated data is stored. Thus, communication with plural slave stations is attained by using two vaves.