Confusion about zcsequence_t and zcsequence_f,and find_zc_angle.

[Marcocd57]

first question:if we use LTE's point, zcsequence_t is directly frequency seq, in find_zc_seq()，author uses zcsequence_t corralte with symbol_f in frequency,so i think author look zcsequence_t as frequency seq in there,but in estimate_channel() function author uses zcsequence_f as frequency expected_signal , why ? next question: in find_zc_angle(): i think author'aim is to find the initial constant phase offset, why use the angle value of zero freq point :angle(symbol_f[NCARRIERS//2]) as the estimation of angle? perhaps DJI dosenot send ZC zeropoint, so set this value to a constant real value,so the receiver can use this point's angle value as phase estimation directly?

[mrlnc]

We've been using time-domain and frequency-domain calculations in several stages and then sticked to what worked best for us. For find_zc_angle we feed the first symbol (index 0, not angle 0) into the function.

If you're diving deeper into the code, I recommend setting debug = True for a GUI with plots. Also, there is a separate Matlab codebase that might be helpful: https://github.com/proto17/dji_droneid

[Marcocd57]

thank you！