The Graves radar uses a multibeam antenna system that is switched every 0.8 seconds. When a meteor is detected and prints a large trace, is easy to see the beam switching after the meteor.
As the Graves radar system uses the transmitter and receiver in different geographic locations, is easy to think that they are synchronized the the UTC.
To check if it is true Miguel EA4EOZ and me are doing stereo recordings stereo of the Graves radar in one channel and a 1PPS signal from a GPS receiver in the other channel. And efectively they are locked to the UTC 🙂
The coincidences to UTC are in the second 0,4,8,12,16,etc.. of every minute.
Some usefull info can be readed on the PE1ITR website.