OFDM technique having the higher PAPR performance has been considered as unsuitable transmission technique for the non-linear satellite channel. To solve this problem, we have already proposed the OFDM-IDAR method, which can mitigate the non-linear distortion and achieve the higher transmission data rate with keeping the better BER performance. In the IDAR method, however the input and output relationships of non-linear amplifier characteristics located at the transmit earth station and satellite are required at the receiver. This paper proposes the estimation method for AM-AM and AM-PM conversions characteristics of non-linear amplifiers by using low PAPR preamble symbols. The various computer simulations are conducted in this paper to verify the effectiveness of proposed method in the non-linear satellite channel.