"The unknown aircraft's signal was sending out intermittently, on and off, and on and off," the spokesman said. The Thai military lost the unknown aircraft's signal because of the limits of its military radar, he said.
It's a shame someone with technical knowledge cannot immediately ask for clarification.
"Unknown aircraft" = Primary
"sending out" = Secondary
Unknown aircraft + Sending = The primary was tracked constantly(unknown) and the SSR was intermittently transmitting garbage data (it's mode s so even without an assigned code you still know who it is)
Perfect example of poor communication.