ASTRON/JIVE Daily Image

© ASTRON

The LIFT project is about using LOFAR2 to measure radio signals that originate from lightning discharges. During a thunderstorm, all the Uniboard2s in all Dutch LOFAR2 stations will continuously record data from all antennas into DDR4 memory on the UniBoard2s. These memory modules on the UniBoard2 are able to store an amount of 4 seconds of antenna data. When a lighting flash occurs, the recording can be stopped by "freezing" the DDR4 memory content. A user can then select a part (equivalent to a timeslice) of the DDR4 memory content that contains the signal emitted by the lightning flash. The UniBoard2 firmware will then dump that selected part of the antenna data via the network, to be stored or processed by the user.

After several months of effort, we have this chain of events now working for the first time on a real Uniboard2. The photo on the left shows the DDR4 memory chips as they are mounted at the bottom of all UniBoard2s in LOFAR2. The screenshot shown at the right shows the first recording and subsequent dumping of 14 packets of antenna data. The monitor points, shown as well, report that the dumped data has the correct checksum (CRC) and correct timestamp (RSN). We used the test rack in the digital lab for this test.

This test shows that the core functionality of the transient buffer function on UniBoard2 works. This test used one FPGA on a UniBoard2, only. The next implementation step is to dump data from all FPGAs in a LOFAR2 subrack.