Testing System of Integer Frequency Offset Compensation Based on DRM

Under Doppler shift, multipath effect and noise interference, frequency offset seriously affects the effect of receiving digital radio mondiale (DRM). For the purpose of obtaining good reception performance, frequency offset compensation is essential. According to the transmission frame structure of DRM system, this algorithm availably uses the pilot symbols of fixed positions, makes the difference between them, and combines them into pilot difference set orderly. The integer frequency offset is estimated by inductive reasoning on the pilot difference set. This method makes the estimation of integer frequency offset more efficient and accurate. In order to verify the reliability of the integer frequency offset compensation algorithm, a transmitting system combined with USRP N210 motherboard and 30MHz RF board is proposed, as well as a receiving system which uses a radio with DRM mode to analyze the audio. The audio quality received by the test system is good, and the experimental effect is considerable.