The present invention provides a transmission signal generating method for a display device to compensate channel effect. The transmission signal generating method includes using a plurality of signal amplitudes and a first signal direction to generate a plurality of positive levels, using the plurality of signal amplitudes and a second signal direction to generate a plurality of negative levels, and using a plurality of signaling lines for transmission of the pluralities of negative and positive levels. A first positive level and a first negative level both have a minimum signal amplitude of the plurality of signal amplitudes. The amplitude difference of the first positive and negative levels is greater than an amplitude difference of any two neighboring levels of the plurality of negative levels and also the plurality of positive levels.