I am not a dsp engineer, so I might be missing some obvious background, but I've been doing my best to educate myself. Let me know if there's more info needed.
I am using an fft cross-correlation algorithm to process 2 channels of incoming microphone audio. The goal is to ascertain the delay between the two audio streams in order to calculate the sound origin in terms of relative distances from each microphone.
I am getting the expected results for my setup: the soundcard and software are running at 48k sample rate, and I have a resolution of 1 sample (0.02 ms) for calculating delays in the streams.
My intended application of this would require a resolution of 0.002 ms or less, and I can't increase the sample rate beyond 48k. So I am trying to get a sub-sample resolution of the cross-correlation using interpolation as described here: How to Interpolate the Peak Location of a DFT or FFT if the Frequency of Interest is Between Bins
I am wondering: Is there a way of predicting what amount of resolution can interpolation (say quadratic interpolation) add to this system?
A bonus question: I'm proposing interpolating the fft results, but would there be benefits to also interpolating/upsampling the incoming audio streams pre-fft?