Design and evaluation of a self-referencing UHF ultrawideband channel sounder

Channel sounding is the process of measuring the channel impulse response (CIR) of a propagation channel by applying a stimulus at one site and evaluating the response at another. Such measurements play art important role in the development of wireless communications systems, which are sensitive to the number, strength, and delay associated with the various multipaths present in the channel. This paper describes an ultrawideband channel sounder which is based on the swept-frequency approach, but which is "self-referencing" in the sense that there is no need to mix portion of transmit signal with the received signal. Instead, a cluster of four CW signals spread over a 1 MHz span is used as the stimulus, and the received signal is digitized at an intermediate frequency (IF). The known characteristics of the stimulus waveform are their exploited to recover a phase reference that remains coherent even as the center frequency of the stimulus is changed.