Patent ID: 7145958

Claim:
A transmission diversity type transmitter in which the same modulation waves are transmitted from transmission units at the same time by delaying a base band signal with delay circuits, and modulation timing is made coincident among the modulation waves at a reception point to achieve a diversity gain, the transmitter comprising: a detector for detecting an RF signal of each transmission unit and outputting a detection signal, a comparator for comparing detection signals output from two detectors of two transmission units in said plural transmission units and outputting a comparison signal, and a delay amount control circuit for controlling the delay circuits of said two transmission units on the basis of the comparison signal output from said comparator so that the modulation timing is coincident at transmission output terminals of said two transmission units, wherein the base band signal is subjected to ON/OFF control, the rising timing and falling timing of the detection output when the ON/OFF control is carried out are compared with each other by said comparator, and said delay circuits are controlled by said delay amount control circuit so that the difference between the rising timing and the falling timing is within a permissible time range.