This paper presents a high speed configurable FPGA-based wideband channel sounder with signal bandwidths up to 200 MHz and results of a study of dynamic urban picocell channel. The use of FPGA allows the sounder to be adaptable for measurements in different scenarios. Adaptable options include changes to the waveform, bandwidth, channel sampling rate and real-time averaging to improve signal-to-noise ratio in weak signal conditions. The implemented architecture has led to a 70% reduction in size and weight compared to sounders in use elsewhere making it ideal for mobile channel measurements. The study of an urban picocell channel has shown that dynamic variation due to automotive traffic introduces average signal strength fades of up to 5 dB but causes frequency selective fading with depths of up to 40 dB. Existing channel models assume antenna heights of more than 6 m and path lengths of more than 30 m. Therefore there is a need for shorter path models and this paper proposes a linear picocell channel model for static and dynamic urban environment.