Add Planning topics Transient detection.

applications/lofar2/doc/prestudy/station2_sdp_transient_detection.txt

+
+Cosmic rays at LOFAR, proefschrift A. Corstanje, sep 2019:
+Cosmic rays arrive on Earth from all directions. These high-energy particles (10**9 to 10**20 eV)
+are atomic nuclei.This is the field of astroparticle physics. At > 10**14 eV the particles is
+too rare to measure directly. Instead they can be mesured indirectly, because they cause a secondary
+air shower of particles when they interact with nuclei in molecules in the atmosphere. The
+air showers produce radio signals, that arrive on the ground as short pulses in the range of 30 -80
+MHz. LOFAR detected first cosmic ray in June 2011 and has detected 2717 pulses up to end 2018. The
+radio pulse is short (10 - 100 ns). The timing of the pulse can be better than the sample period
+and depends on the SNR.
+
 1) Transient detection (TDet) Design
 
 - no self triggering yet for MVP
@@ -71,7 +82,7 @@ CR, LI pulse duration in comlex envelope is ~50 - 100ns
 . CR ~ 1 pulse per min
 
 LI binning in time, to limit maximum message rate
-. bin time fixed in time of 10 - 100 us
+. bin time fixed in time of 10 - 100 us --> 10000 - 1000 bins/s
 . only report strongest event during bin
 . typically each bin will show an event during a flash
 
@@ -85,3 +96,75 @@ Message
 . timestamp of crossing threshold (or of maximum after crossing threshold until uncrossing threshold?)
 . max level of pulse is not needed
 
+
+5) Planning topics Transient detection
+
+- Comparison with LOFAR1 [1, 5]
+  . IIR filter with programmable coefficients to implement:
+    - HPF (> 30MHz), BPF
+      . An IIR ellip BPF needs about order 10 to achieve-40 dB at 30 and 80 MHz, so 5 biquads
+    - or notches (one at 15 MHz short wave band, one at 88 MHz FM band)
+      . filtering of FM band increases SNR, short wave band filtering increases stability of SNR
+      . in LOFAR1 we implemented a three stage filter in which the parameters b0, b1, b2, a1, a2 can
+        be set. By choosing different values for the parameters one can implement a high-pass,
+        low-pass or notch filter.
+      . With one biquad per notch the attenuation at f0 is strong, but the notch bandwidth is small
+        (~3 MHz at -20dB, ~10 MHz at -10dB)
+  . peak detect if abs > mu + k * sigma --> simplifies to --> abs > k2 mu for Gaussian signal
+  . binning for LI, because 10000 triggers / flash, so only trigger strongest per bin (= time slot)
+- Comparison cosmic ray and lightning [1, 2]
+  . Check that LI binning is transparant to CR
+  . Format of detection message
+- Requirements, MVP
+  . number of signal inputs per FPGA (max 12 single pol)
+  . one polarization per antenne ?
+  . CR signals are small and often vary significantly over the distance of a single station.
+    Number antennas of the order of 20 are required distributed across the station [1]
+- Detection algorithm analysis in Python:
+  . Operate on raw data or on subbands ? --> ik denk raw want CR pulse duurt < 20 ns
+  . BPF for RFI suppression: 30 - 80 MHz bandpass, possibly with notch filters
+  . complex envelope, abs amplitude calculation, running average, threshold detection
+  . Verification (parameter tuning) with existing TBB data from LOFAR1
+- L4 SDPFW Decision: TDet
+- L5 SDPFW Design: TDet
+  . Architecture
+    - Block diagram
+    - Signal levels and quantization
+  . Monitor and control
+  . Implementation
+    - Efficient mapping on DSP multipliers
+    - New components
+  . Verification in simulation
+  . Verification on hardware
+- L2 ICD SC-SDP OPC-UA interface
+  . CP and MP
+  . Dynamic behavior
+- L1 ICD STAT-CEP interface
+  . Detection message ICD:
+    - format (destination, application info) and control (enable per signal input, rate)
+    - forced message every 30 s to show alive
+
+
+6) TBuf planning for comparison [7]:
+- R_booked = 1.7: Booked time in days = R_booked * N_story_points
+- R_lead = 2.1: Lead time in days = R_lead * N_story_points
+- SDP Design: N_story_points = 29 story points --> N_booked_days = 49
+- SDP Realisation: N_story_points = 93 story points --> N_booked_days = 158
+- SDP hours: (49 + 158) * 8 = 1656 hours
+
+References:
+ [1] https://support.astron.nl/confluence/display/L2M/2023-04-18+Meeting+notes+Preparation+CR+group+meeting?preview=/117413179/117413191/Cosmic_Rays_Firmware_Implementation_Document%20comments%20BH.pdf
+ [2] https://support.astron.nl/confluence/display/L2M/2023-04-13+Meeting+notes+update+session+with+Cosmic+Ray+group?preview=/117411807/117411963/20230413%20Comparison%20LIFT%20vs%20CR%20use%20cases.pdf
+ [3] https://www.sgo.fi/KAIRA/LOFAR-ASTRON-MAN-064_v12.pdf --> in Documents/LOFAR2/References/LOFAR1_station/
+
+ [4] Doorduin. TBB Transient Detector User Manual. Technical Report LOFAR-ASTRON-DDD-056,
+     ASTRON, Dwingeloo (The Netherlands), November 2009.
+ [5] A. Horneffer and S. Laf`ebre. The LOFAR VHECR Trigger. Technical Report LOFAR-ASTRON-
+     SDD-055, ASTRON, Dwingeloo (The Netherlands), March 2007 --> in https://support.astron.nl/confluence/display/L2M/Temporary+storage+of+documents+and+papers
+
+ [6] Air_shower_measurements_with_LOFAR_2009.pdf
+
+ [7] https://support.astron.nl/confluence/display/SBe/SDP+Transient+buffer+planning+experience+and+estimate
+
+VHECR = Very High Energy Cosmic Rays
+