hongp:
Can you explain how you get 92.5 million samples is necessary to have six digits of resolution at 9259hz sampling rate? and how you figure out the size if 185 mB?
It's the formula I showed earlier. The resolution of the FFT is sampleRate/sampleCount. To get resolution of 0.0001 Hz (1/10,000th Hz) you need sampleCount to be 10,000 times the sampleRate.
If each sample is a 2-byte integer you need 2*sampleCount bytes to store them.