normalised FFT implementation

[Mahesh0459]

Hi everybody, I started learning labview since 4 months & i started labview FPGA also. I wnated to know how can i normalise FFT results to 0 db in labview fpga. In matlab we will take maximum value and apply devide to make to 1 and apply log to make into 0. But how can i do the same thing on Labview  FPGA. I am using 7975 hardware. I am able to find FFT but its moving . If i give a 1Mhz signal to FFT the moving from 500khz to 3 Mhz also. I need to get constant output. Everything should be on FPGA not on Host. On Host we have FFT to spectrum convertion. I dont want to use that also. Just i have to read fifo on host thats it. I know for a N point FFT we need to take only +ve's that is N/2 samples.