The SPS at high intensities exhibits transverse singlebunch
instabilities with signatures consistent with an
Ecloud driven instability.[1] We present recent MD data
from the SPS, details of the instrument technique and spectral
analysis methods which help reveal complex vertical
motion that develops within a subset of the injected bunch
trains. The beam motion is detected via wideband exponential
taper striplines and delta-sigma hybrids. The raw sum and difference data is sampled at 50 GHz with 1.8 GHz bandwidth. Sliding window FFT techniques and RMS motion techniques show the development of large vertical tune shifts on portions of the bunch of nearly 0.025 from the base tune of 0.185. Results are presented via spectrograms and bunch slice trajectories to illustrate development of the unstable beam and time scale of development along the injected bunch train. The study shows that the growing unstable motion occupies a very broad frequency band of 1.2 GHz. These measurements are compared to numerical simulation results, and the system parameter implications
for an Ecloud feedback system are outlined.