A bistatic backscattering system architecture and its noncoherent modulation scheme based on Frequency Shift Keying(FSK) are proposed in order to realize the applications requiring large amount of wireless sensor coverage and large communication range. Firstly, the backscattering signal and the channel model for the bistatic backscatter system architecture are analyzed in detail. Then, on this basis, an FSK based noncoherent modulation and techniques to overcome carrier frequency offset introduced by the utilization of bistatic architectures are proposed for power-constrained cases. Finally, the receiver chains based on FSK and the Bit Error Rate(BER) calculation are provided. The experimental results show that the proposed bistatic backscattering architecture and its FSK based modulation and demodulation technologies not only have good BER performance, but also have the potential of large communication range, which is applicable for large-scale and power-constrained sensor networks.