so you think the little 20 or so dollar handheld audio rpm devices have some high dollar descrete audio components amounting to more than a condenser mike and some complimentary components?
what frequencies would you expect to see when trying to find rpm ? from zero to 1000 hz(0-60k) would be my guess id filter everthing else out on the top and bottom end.Even more so for the big blocks coz you wont expect to see 60k with that. Alot of the software ask for a range you expect to see. Im sure thats to filter out eronious frequencies and just look for what you want .
Jeff, to answer your question yes I think the new smart phones which have high definition audio as well as eq and sound tailoring, apps like "RTA's" and such can handle the job well enough. If there is a percentage difference consistency youd just factor it in.
As far as doppler is concerned I would think that the ear or mike would remain in the same position while only the source moved in this scenario but id simply take the measurement when the boat passes right in front. Its true that with the tach not being on the boat it will be subject to some doppler if you put the phone in the boat while running that would take care of doppler yes or no? I also think that all the audio tach devices have a +/- accuracy to some degree that acceptable for what were doing here.
Jeff please elaborate.
