A time-frequency analysis of EMP data taken on the Vulcan Petawatt is presented. The time-frequency analysis applies a scanning time-window across the data within which the frequencies are resolved with a Fourier transform. As the frequencies of the measured EMP signal range from megahertz to gigahertz applying different scanning window lengths maximises the temporal information obtained, the considerations that need to be taken into account is discussed. Measurements of EMP signal have been taken at different locations simultaneously along the same line of sight within the Vulcan Petawatt interaction chamber. The initial analysis of this data will be presented looking at how the signal changes when it propagates across the chamber.