A sound wave moves 85 mm in that time at Mach 1, around 340 m/s. That doesn't mean we need to sample a sound that has no components above 20 Hz, using 4000 samples per second.
The propagation speed can be misleading.
All that matters is whether there are oscillations in the suspension that go up to 1800 Hz, not how fast the car is going forward. If there are, those would have to be harmonics. You'd think would be beyond the frequency response of the suspension. Suspensions are heavy, bulky components and are heavily dampened (which is a kind of low-pass filter).
If the suspension moves anywhere near 17 mm per sample (250 km/h vertically), that car is in serious trouble.
> All that matters is whether there are oscillations in the suspension that go up to 1800 Hz
Surely you care about more than just oscillations, for example how exactly the suspension compresses during breaking. If you've seen slow-mo shots from high-speed race cars riding a curb, it can be quite violent with lots of movement.
In this article[1] about Formula 1, they state they sample vibration data at 200kHz. This is then filtered to a lower rate for logging, but getting say 5kHz out of 200kHz raw sensor data doesn't seem unreasonable to me.
They also mention they collect about 30MB per lap of sensor data from more than 250 sensor, and laps are typically around 1.5-2 minutes long. If one assumes a 2 minute lap and 250 sensors, that's 1kB/s per sensor on average.
> how exactly the suspension compresses during breaking
The entire graph of suspension vs time should be well below the frequency range. It doesn't matter whether we are looking for frequency domain features or time domain features.
(Like someone said upthread, it's probably 4000 events per second as an aggregate from numerous sensors, mutiplexed into one sqlite. Or maybe even a total across the three sqlites.)
I found this page[1] which mentions dynoing shocks at 3 inches per second, as that what one could see in the pits. If you want some spatial-temporal resolution for that then you'll want a fairly decent sample rate, no?
Maybe not quite 4kSps is needed but for vibration and such it'd make sense to me.
3 inches per second is very slow. I think shocks compress quite a bit faster when you hit a speedbump in a parking lot.
The sample rate you need to reconstruct the motion of shocks is entirely determined by Nyquist, just like sampling audio or any other signal.
You need some 2.2x the highest frequency you want to capture, and make sure you filter out anything above that (if it exists).
If there is nothing above 20 Hz in the suspension's movement, or nothing you're interested in, then you need a 44 Hz sample rate. (More if you implement oversampling, but not 10 times more let alone 100.)
The propagation speed can be misleading.
All that matters is whether there are oscillations in the suspension that go up to 1800 Hz, not how fast the car is going forward. If there are, those would have to be harmonics. You'd think would be beyond the frequency response of the suspension. Suspensions are heavy, bulky components and are heavily dampened (which is a kind of low-pass filter).
If the suspension moves anywhere near 17 mm per sample (250 km/h vertically), that car is in serious trouble.