diff --git a/applications/lofar2/doc/prestudy/lift_lightning.txt b/applications/lofar2/doc/prestudy/lift_lightning.txt index b4104d70022d0784fcc01a7b814b0863145f041f..b62fc976a0795e630e0734744b5b16018c23db06 100644 --- a/applications/lofar2/doc/prestudy/lift_lightning.txt +++ b/applications/lofar2/doc/prestudy/lift_lightning.txt @@ -1,7 +1,9 @@ -LIFT 27 June 2022 meeting +1) LIFT 27 June 2022 meeting + +a) Transient buffer: - only raw, no subband data - cosmic ray uses all antennas of one station, lightning ~ 6 antennas but all Dutch stations . 6 dual pol antennas per station with long baselines @@ -9,8 +11,16 @@ LIFT 27 June 2022 meeting - cosmic ray is commensal, lightning is dedicated mode - cosmic ray 2 ms event, lightning 1 s events - individually controlled antenna buffers -- transient detection based on power after 40 - 80 MHz BPF -- read out via LCU (with local storage, later TCP to CEP) or directly to CEP (UDP) +- read out via 10GbE via LCU (with local storage, later TCP to CEP) or directly to CEP (UDP) + . one signal input for 1 s takes 200M * 16b = 0.4 GByte = 3.2 Gbit, so 0.3 s + . 192 signal inputs for 1 s takes 3.2 Gbit * 192 ~= 0.6 Tbit, so 60 s - 2 * 8 GB / (12 * 16b / 8b * 0.2 GHz) = 3.33 s seems enough storage . 3.33 * 16b / 14b = 3.81 s . header overhead 5 % --> 3.81 * 0.95 = 3.61 s + +b) Transient detection: +- notch filter ? +- transient detection based on power after 40 - 80 MHz BPF +- measure power during 10 us to detect pulse, if > threshold then send pulse detection events + per signal input via 1GbE +- e.g. use dead time after a detection to avoid storm of event messages