Navio2 Ublox M8N GPS Receiver Measurement Lag

We did some survey about Navio2 Ublox M8N GPS Receiver Measurement Lag compared to IMU and most of them says it around 500ms. Is this true?? But when it comes to APM EKF implementation they consider that gps measurement lag is 220ms. Why is that?? To verify the gps measurement lag compare to IMUs we did some experiment.It also proves that the measurement delay is around 500ms for this receiver type. We are try to implement kalman filter for position and velocity estimation for quadcopter. Any advice appreciate. Thank you.

Hi! It depends on the configuration of the receiver. APM sets Ublox to run on 5Hz, thus the period is 200ms. 20ms seems to be caused by the duration of the message transmission from Ublox.