"One file will give a SNR of up to 40 (if your PC/Soundcard setup is good)  
this file is from an exciter directly.

The other 2 files are good off air recordings and will give SNR of up to 27 dB."

dm_1_if12.wav
dw_2002-10-03_01045_15230_B_64_pl3.wav
dw_2002-10-03_0945_15230_B_64_pl3.wav