To supply a test signal for simulating the real signal of M pieces of symbols, in which several symbols are synchronizing symbols and the other symbols are data symbols, in a fixed format by combining a logic means, pseudo random number generator and synchronism generator.

This test signal generator generates the test signal of pseudo random data for simulating a ground alience transmission layer signal corresponding to 8 or 16 residual side wave band (8/16-VSB) for advanced television(ATV) system in the fixed format. A counter 12 supplies the number of symbols by counting the number of clocks and further supplies the number of segments by counting the number of these symbols. When the number of symbols is '1', a logical arithmetic unit 14 lets a pseudo random number generator 18 generate plural pseudo random numbers and at the same time, when the segment to be simulates is a data segment, a synchronism generator 16 generates four synchronizing symbols. Further, the logical arithmetic unit 14 includes the suitable number of all symbols and simulates the data frame of random, Reed- Solomon coding, alternate arranging and trellis coding.