A recoding medium storing a computer program, which, when executed by a processor, cause the processor to perform operations including: determining a pattern of a change in luminance, by modulating the signal to be transmitted; and transmitting the signal, by at least one light emitter changing in luminance according to the determined pattern of the change in luminance. The signal has a plurality of blocks, each block of the plurality of blocks includes (i) address information that indicates a position of a data segment in the signal and (ii) the data segment. In the transmitting, the signal is transmitted repeatedly at different times. The address information is used to identify a same location of the block data segment in the signal transmitted at a first time and in the signal transmitted at a second time, which is different from the first time. The signal has a check signal.