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Last modified by robert on 2026/02/27 19:58
From version 105.2
edited by robert
on 2026/02/17 12:43
Change comment: There is no comment for this version
To version 105.5
edited by robert
on 2026/02/17 15:49
Change comment: There is no comment for this version

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444 444   'gain':1.69726e-05,
445 445   'sensitivity': 702651512.6046528}
446 446  
447 -*image TBA but they have been created in the past~-~- we are 100% confident our published responses are correct
447 +[[X axis is samples (.01 s), Y axis is velocity (m/s), 0.5-5 Hz filter>>image:BD3C_Z_huddle.png]]
448 448  
449 -== Horizontal noise & how to avoid ==
449 +[[X axis is samples (.01 s), Y axis is velocity (m/s), 0.5-5 Hz filter>>image:BD3C_N_huddle.png]]
450 450  
451 -The 5 Hz nodes are susceptible to horizontal noise due to the placement of geophones in the units, **but this can be mitigated by completely burying the units flush with the ground.** In the below example, the node was set on the floor of our basement set on its plastic carrying case support. As such the amount of horizontal noise noticeably increases above ~~ 10Hz.
451 +(% class="wikigeneratedid" %)
452 +Below the corner frequency 0.2 Hz (i.e. 5 seconds) the response still does a good job, but may need to be dialed in a bit. We are looking into this.
452 452  
453 -[[Power spectrum huddle test vs a CMG-6TD (S1) and TC120/Centaur combo. The N and E channels have excess noise above 10Hz due to "sticking up" out of the ground.>>image:IGU16_spectrum.png]]
454 +(% class="wikigeneratedid" %)
455 +
454 454  
457 +[[BD3C 0.1 to 5 Hz bandpass>>image:BD3C_Z_huddle.0.1.png]]
458 +
459 +[[BD3C 0.1 to 5 Hz bandpass>>image:BD3C_N_huddle.0.1.png]]
460 +
461 +== IGU-16 Horizontal noise & how to avoid ==
462 +
463 +The** 5 Hz nodes** are susceptible to horizontal noise due to the placement of geophones in the units, **but this can be mitigated by completely burying the units flush with the ground.** In the below example, the node was set on the floor of our basement set on its plastic carrying case support. As such the amount of horizontal noise noticeably increases above ~~ 10Hz.
464 +
465 +[[IGU-16HR-3C Power spectrum huddle test vs a CMG-6TD (S1) and TC120/Centaur combo. The N and E channels have excess noise above 10Hz due to "sticking up" out of the ground.>>image:IGU16_spectrum.png]]
466 +
467 +(% class="wikigeneratedid" %)
468 +The BD3C-5 nodes do not have this issue:
469 +
470 +[[BD3C-5 test, as above. There is no additional noise on the horizontal channels.>>image:BD3C_psd.png]]
471 +
455 455  = **Cleaning** =
456 456  
457 457  When assembled, the nodes are water resistant but not submersible. They can handle a good spray and wipe-down. A stiff plastic brush is helpful to reach areas between the metal spikes on the bottom.
BD3C_N_huddle.0.1.png
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