Home › Forums › Mooshimeter Support › Logged Data vs Sampled Data
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My understanding of the buffer depth and sampling interval is that if they are set to 32 and 125Hz respectively, the mooshimeter would be gathering 4000 data points per second. Each 32 would be averaged together to 125 data points per second. Lets say I set my logging rate to 1 second, how do I go from the 125 averaged data points (gathered in one second) to the logged data point? Are they averaged? What about setting the logging rate to 10s?
Thanks in advance!
What you see as sampling settings is what is happening in your mooshimeter. So 32smpl/125Hz would be just that, nothing to do with 4000.
With those setting, every one value, for log or user interface, is generated by taking samples at 1/125 s intervals, 32 times in a row and then averaging (or some RMS stuff for AC) those. That would take some time, roughly 32/125 s + ~0.1 s for processing. And then, repeat from the start. If you set logging intervals to “no wait”, those settings would give you roughly 3 values per second.
As you set higher samplerates, you quickly realize that you can’t get past ~10 log-lines per second, as processing still takes same time every round. In some cases, you might want to set samplesize to bigger value, for more stable results. That again would mean it takes more time to get those samples and rate that you get new values would drop. Max samplesize times lowest samplerate takes over 2 seconds for a round. You just need to know what you are trying to measure and what is it that you want to see from your data. If there is time to spare before next logging interval, mooshimeter goes to sleep to save power. In that last example, nowait and 1s interval settings would still both give you only one log line every 2 seconds.
As always, i’m afraid to read the question again, probably wondered quite far from what i should have written :D
To be clear, you’re saying with a sample rate of 125Hz and a buffer depth of 32 the mooshimeter will sample at the following times: 1/125, 2/125.. 32/125. Then compute the average over the first 32 data points and for the remaining 93/125 seconds there is no data gathered as I would have the log setting set 1s as opposed to “no wait”?
Lets say the signal I wanted to measure could vary wildly within a second, for instance every 100ms it changes, then would a sample rate of 125Hz and buffer depth of 128 be able to measure it at each 1/125s interval up to 128/125? How is the extra 3/125 handled when logging every second?
Sampling settings are “stronger” than that logging interval.
So if sampling+processing takes more time, you basically get new log lines at the rate mooshimeter is able to produce them. In that example, there should be no difference between no wait and 1 second settings and both should give you results every ~1.1 seconds.
With mooshimeter, you cant see the whole signal anyway. There are always those processing pauses between sampling. Fast sampling with small sample size might catch your quickly changing signal and lower sample rate with bigger sample size would smooth random spikes out and might make it easier to see slower phenomenons.