We use ardupilot in our VTOL aircraft. We have a buyer for UM980. We are receiving some NMEA messages on this receiver. For example GGA, RMC, AGRICA, HWSTATUS, FREQJAMSTATUS, KSXT. Ardupilot configures these messages. The AGRICA message continues to arrive irregularly at some times. While it should come in 200 ms, there are cases where it comes in 500 ms and 800 ms. We cannot find the reason.