A Tetherless, Absolute-Time Channel Sounder, Processing, and Results for a Complex Environment | NIST

We present a channel sounder that can operate without a tether and still maintain an absolute time reference between the source and receiver. Based on a sliding correlator, with synchronized rubidium clocks to generate phase references for the upand downconverted RF carriers, and a synchronous trigger, the system generates locked signals in the short term (tens of hours). The system has an operational range of 10 MHz to 6 GHz with an instantaneous channel bandwidth of up to 200 MHz. We start with a discussion on processing measurements for oversampled band-limited signals. Spectral truncation is compared with transmit spectrum filtering; DC bias removal and referencing to remove systematic effects are discussed. We conclude with channel sounding results, power delay profile, RMS delay spread, and time of arrival versus position for an electromagnetically complex environment.