Digital techniques for mobile radio chirp sounders
Sana Salous, N. Nikandrou, N.F. Bajj · IEE Proceedings - Communications · 1998
The theory of chirp sounding is briefly reviewed. This is followed by the description of a digital mobile radio chirp sounder which is implemented using direct digital frequency synthesisers (DDFS), field programmable gate arrays and microcontrollers. The gate arrays and the microcontroller provide the user interface via either a keypad or a PC, generate the programming words for the DDFS and two phase-locked-loop (PLL) synthesisers, synchronise the transmitter’s sweep to the receiver’s sweep and implement a beat-frequency-oscillator DDFS. Results demonstrate that the digital chirp sounder provides full programmability of the various chirp waveform parameters, bandwidths up to 90 MHz which are suitable for both indoor and outdoor environments, offline processing to obtain different channel characteristics, and moderate averaging to obtain a dynamic range better than 35 dB.