How do you measure phase difference between two wideband signals

Question

I am receiving a signal from two antennas, and I wish to compare phase in order to extract angle. I know that you would usually use a phase comparator. I was wondering whether this would work only with pure single tone signals or with more wideband signals as well. My signals have a bandwidth of about 2KHz (not so wide, but does it make a difference?).

I understand now that I am actually not looking for the phase difference but rather time difference. Wondering whether this could be done in analog.

Thanks

Answer 1

Assuming you receive the same signal via two antennas, you can apply convolution to detect the delay between the two signals:

The peak of the convolution corresponds to the delay between the two signals (on the picture above, both signals are identical so the convolution peak lands on zero). You can transform that delay into a phase shift for a given frequency.

Convolutions are hard to do using analog circuits, so I suggest you reconsider your constraints to see if you can fit a DSP in your design. However, there are special cases where convolution can be realized in analog circuits rather easily. For example, if the signal you're receiving has a fixed profile, and you can figure out an LTE system those impulse response matches your signal profile, then applying convolution is as easy as feeding the signal to that LTE system. This rarely helps in practice though.

Answer 2

It's a hard problem. You can FFT the signals, compute the phase and amplitude of all components, and (except for an arbitrary integer times 2pi) find a weighted average phase for each, and take the difference. There's gonna be more than one component, though, so the 'phase difference' isn't a constant, it's a component-by-component listing.

If you consider only one component, you've filtered the signal under consideration by making that choice, and the bandwidth is different from the original signal.