Skip to content
Snippets Groups Projects

Add plot_iir_filter_analysis() based on LTF-IIR-allgemein.ipynbcode from...

Merged Add plot_iir_filter_analysis() based on LTF-IIR-allgemein.ipynbcode from...
RTSD-242 into master
Merged Eric Kooistra requested to merge RTSD-242 into master
Compare
and
15 files
+ 2923
− 462
Compare changes
  • Side-by-side
  • Inline
Files
15
applications/lofar2/doc/prestudy/station2_sdp_transient_detection.txt
+ 84
− 1
 
 
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
1) Transient detection (TDet) Design
- no self triggering yet for MVP
- no self triggering yet for MVP
@@ -71,7 +82,7 @@ CR, LI pulse duration in comlex envelope is ~50 - 100ns
@@ -71,7 +82,7 @@ CR, LI pulse duration in comlex envelope is ~50 - 100ns
. CR ~ 1 pulse per min
. CR ~ 1 pulse per min
LI binning in time, to limit maximum message rate
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
. only report strongest event during bin
. typically each bin will show an event during a flash
. typically each bin will show an event during a flash
@@ -85,3 +96,75 @@ Message
@@ -85,3 +96,75 @@ Message
. timestamp of crossing threshold (or of maximum after crossing threshold until uncrossing threshold?)
. timestamp of crossing threshold (or of maximum after crossing threshold until uncrossing threshold?)
. max level of pulse is not needed
. 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