PURPOSE: To contrive miniaturization and light weight of the titled receiver and to easily judge a good reception system, by transmitting a surplus bit as a fixed pattern, and detecting the data of the fixed pattern in reception data at the reception system.

CONSTITUTION: A signal received by a main antenna 11, whose frequency is selected and amplified by a main receiver 12, and is inputted to a main demodulation part 13, then it is demodulated to a data signal, and is inputted to a main frame synchronizing circuit 16, and a synchronous code in a transmission format is detected. Based on the above detected result, the position of the fixed pattern in a transfer frame is indicated to a main error rate deciding apparatus 15, and the bit different from the fixed pattern in a fixed pattern period is decided as an error. Meanwhile, exactly the same operation as that of the main reception system is also performed in a sub-reception system, and the error rate from the main error rate deciding apparatus 15, is compared with the error rate from a sub-error rate deciding apparatus 25, at a comparator 31, and the reception system with low error rate is decided. A data switching apparatus 32 is controlled by the above decided result, and the data of the reception system having a smaller error rate is selected.