Beidou satellite navigation system (BDS) contains subtle nominal deformations. The traditional research focuses on deformation of single satellite and cannot quantitatively calculate the ranging biases due to nominal deformations. This paper analyzes BDS B1I signal nominal deformations based on time waveform

channel characteristics and ranging biases. The data are from big antenna receiving system combined with software receivers. Firstly

the cumulative averaging method and standard chip correlation technique are used to extract the details of signal deformations

and the digital distortion value of each satellite is calculated. Then

channel characteristics of all satellite signals are analyzed based on least square method. Lastly B1I signal natural ranging biases and the maximum ranging biases are analyzed quantitatively by S-curve bias. The nominal deformations of B1I signal are comparatively studied from multiple dimensions and the results presented could provide a new thought for signal-in-space assessment and receiver design.