Distinguishing Wind-Driven From Structural Sound in Open Skylights

The SuperCam microphone on Perseverance sampled 25 kSPS of Martian wind and turbulence at 20 Hz to 50 kHz, and the turbulence floor at the pit rim can mask the structural reverberation a mapping payload actually wants. Separating wind from structure is the single hardest signal-processing problem EchoQuilt solves at an open skylight. This post walks through the classifier and shows how the quilt stays stable when Martian aeolian signal swings an order of magnitude in a sol.

An acoustic payload sitting on the rim of an Arsia Mons lava tube skylight records a spectrum that mission planners and atmospheric scientists have been studying together for years. AGU/Wiley's analysis of wind and turbulence observations with the SuperCam microphone on Perseverance reports 25 kSPS sampling across 20 Hz to 50 kHz, with turbulence features in the 20 Hz band that dominate the low-frequency end of the spectrum and swing in amplitude over the course of a sol. The Springer description of the SuperCam instrument suite on the Mars 2020 rover gives the microphone's 100 Hz-10 kHz design band, and the PMC report on the Mars soundscape shows that 5 hours of surface recordings are dominated by turbulence events even at the relatively quiet Jezero crater landing site.