How to obtain the phase of received signals with transmitted signal using PYNQ-MTS?

Hi, I am using PYNQ-MTS to transmit and receive signals in sync.
To achieve my application, it is required to receive four channels in sync and need to obtain the phase of received signals with the transmitted signal. Reading the manual, there are I/Q mixer on RFDC blocks, and I think it is possible to convert the data to IQ signals. However, I could not find the way to do this with the MTS module. Is this possible with PYNQ-MTS? If possible, how can I achieve this?
Thank you for your kind advice.

(EDIT)
“mtsOverlay” class has internal_capture(), which captures only three channels despite the board has four. Why does this function not scan all four channels?