Analysing 2500 frequencies using FFT with an input vector of 2048 samples?
The first 1024 output bins of the FFT represent frequencies from 0 Hz to Fs / 2 = 2.5 kHz. So each bin is 2500 / 1024 = 2.44 Hz wide. In other words you have a resolution of 2.44 Hz in the frequency domain.