1 / 31

Status of the BRAMS project & plans for the future

Status of the BRAMS project & plans for the future. Hervé Lamy & BRAMS team Royal Belgian Institute for Space Aeronomy. METRO annual meeting 2016 Brussels – 29 November 2016. Meteor forward scatter. BRAMS network. 2 new stations in 2016 : Haacht and Sivry-Rance. f = 49.97 MHz P=150 Watts

annmiller
Télécharger la présentation

Status of the BRAMS project & plans for the future

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Status of the BRAMS project & plans for the future Hervé Lamy & BRAMS team Royal Belgian Institute for Space Aeronomy METRO annual meeting 2016 Brussels – 29 November 2016

  2. Meteorforwardscatter

  3. BRAMS network 2 new stations in 2016 : Haacht and Sivry-Rance f = 49.97 MHz P=150 Watts Circularly polarized 32 stations 2 stopped 2 inactive

  4. Typicalreceiving station AGC off RG213 Spectrum Lab

  5. Typicalreceiving station

  6. BRAMS data BEOTTI – 01/02/16 – 12H40 Raw WAV data 5 minutes Fs = 5512 Hz Spectrogram : 0 to Fs/2 =2756 Hz nFFT=16384 ; overlap=90%

  7. BRAMS data Filtered raw data between for frequencies > 1200 Hz and < 1000 Hz f  0.33 Hz t  3 sec

  8. BRAMS data BEUCCL – 04/01/16 – 04H55 Quadrantids – More noisy station

  9. BRAMS data

  10. Future plans for hardware • 2-3 more stations per year (see strategy during talk on trajectories) • Use SDR-like receiver (e.g. Dongle) instead of ICOM-R75 + external sound card. Also use single-board computer (e.g. Raspberry-Pi) instead of local PCs. Internship of a student from EPHEC in early 2017. Goal is to increase reliability, control, decrease cost & keep stability & sensitivity. • Answer an important question about using Yagi antenna vertical vs inclined

  11. Antenna vertical vs tilted BEMAAS BEOVER BEGENK

  12. 9 meteors Local effects only? Or also influence of the direction of the antenna? 14 meteors 6 meteors

  13. What is at stake? 2 questions : 1) are we detecting the same meteors? 2) can we accurately determine the radiation pattern of an inclined antenna?

  14. Tests in BEUCCL Sensitivity too low for tilted antenna due to use of a set of connectors and/or oxydation

  15. Automatic detection of meteor echoes in BRAMS data

  16. Method using the time signal See Roelandts (2014)

  17. Method using the time signal Band-pass filtered signal to remove noise / possible parasitic signals

  18. Method using the time signal Ratio of energy content in a short window (101 points  101/5512  0.018 sec) and in a large window (30001 points  30001/5512  5.44 sec) Indicator signal • 3 parameters : • Short windowlength • Large windowlength • Threshold

  19. Test of the method : manualcounts Fichier csv with coordinates of all the rectangles

  20. Comparisonmanual – automaticcounts • Detection: everythingdetected by TR/automaticmethod • Manual: everythingmanuallycounted (lines of the CSV files) • TRUE POSITIVE: TR methoddetectssomethingwhichfallsinto a rectangle • FALSE POSITIVE: TR methoddetectssomethingelsethan a meteorecho • FALSE NEGATIVE: TR method misses a meteorthatwasmanuallycounted

  21. Variation of the threshold BEUCCL : 0H00 – 0H55

  22. Variation of the threshold BEUCCL : hour by hour Goal : check if threshold varies during the day

  23. Variation of the threshold BEUCCL – Whole day

  24. Choice of the threshold • Varies from station to station • Does not seem to vary significantly during one day • Difficult to define a simple criterion to select it, so mostly chosen empirically so far.

  25. Interferences • Visual inspection of the FP reveals that 30-40 % of them are due to broad-band interference • Some may be weak and barely visible • Easy to remove a posteriori by filtering the signal inside the 200 Hz range where meteor / airplane echoes occur. Remaining peaks are interferences

  26. Interferences

  27. Origin of some FP ?

  28. Simulations of IS Gaussian noise with mean=0.1 and std=0.1

  29. Simulations of IS Noise + beacon

  30. Simulations of IS

  31. Future plans • Finalise the tests with TR’s method : comparison with manually counted data from several stations, data from the Quadrantids (HL + RMZ) & Perseids (RMZ). • Continue simulations of IS with 2 goals : 1) automatically select a range of threshold to search for the optimal value, 2) try to understand some of the false detections • Set up this automatic method and apply it to archived data from January/February 2017 in order to produce raw counts per day & per station • Continue to investigate other methods

More Related