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From: Jan Panteltje <alien@comet.invalid>
Newsgroups: sci.electronics.design
Subject: Re: OT: sound speed depends on frequency on mars
Date: Sat, 31 Aug 2024 07:31:52 GMT
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On a sunny day (Fri, 30 Aug 2024 07:34:05 -0700) it happened john larkin
<jlarkin_highland_tech> wrote in <vgl3dj9uq2t9bmo6miqr8faaiuoi1d24c2@4ax.com>:

>On Fri, 30 Aug 2024 11:13:05 GMT, Jan Panteltje <alien@comet.invalid>
>wrote:
>
>>NASA's Mars rover Perseverance has found that sound travels much more slowly on the Red Planet than it does on Earth
>>and behaves in some unexpected ways that could have strange consequences for communication on the planet.
>> https://www.space.com/nasa-mars-rover-perseverance-speed-of-sound#main
>>  At frequencies above 240 Hertz, "the collision-activated vibrational modes of carbon dioxide molecules do not have enough
>>  time to relax, or return to their original state,"
>>  the researchers said, which results in sound waves at higher frequencies traveling more than 32 feet per second (10 m/s)
>>  faster than the low-frequency ones. 
>>  That means that if you were standing on Mars, listening to distant music, you would hear higher-pitched sounds before you
>>  would hear the lower-pitched ones. 
>>
>>paper:
>> https://www.hou.usra.edu/meetings/lpsc2022/pdf/1357.pdf
>>
>>So...
>>Music from far away may sound funny?
>>
>>For Mars we will need compensation headphones with distance measurement and variable delays....
>>;-)
>>
>>Better use radio.. and earplugs/ headphones...
>>
>>
>>
>
>Funny, I just delivered a lecture on transmission lines and noted that
>microstrips have dispersion from  the unbalanced dielectric constants
>and skin effect. Rising edges get sloppy at the and of a long trace.
>
>I wonder if anyone has added surface-mount Heaviside loading coils to
>a PCB trace.
>
>https://en.wikipedia.org/wiki/Loading_coil
>
>There used to be millions of 88 mH toroids on the surplus market,
>telephone loading coils.
>
>The Mars thing is no big deal. You'd be dead too soon to worry about
>acoustics. Imagine Burning Man (literally!) on Mars.

It may matter for sonar based systems, distance measurements etc..
I have some small sonar based modules in use from ebay, something like these:
 https://www.ebay.nl/itm/185960647108