AVM SYSTEM

PURPOSE:To prevent the increase in the occupied time of a radio wave due to re-transmission processing by reducing trouble required for time matching of a built-in timer of an AVM slave station equipment in the AVM system so as to eliminate the repetition of useless re-transmission processing. CONSTITUTION:An AVM slave station equipment 26 is provided with a timer calibration function 31 requesting calibration time data for an AVM master station equipment 38 to match a time of a built-in timer 8 at application of power, a retrial stop function 34 monitoring an ACK signal to limit useless re-transmission processing and a retrial return function 35 restarting the re- transmission stopped by the said retrial stop function 34 when an ACK signal is received by the succeeding transmission and a retrial interval adjustment function 36 using a random number so as to set a retrial interval.