5 ms·
> given that you need 16 decently high quality microphones... But... you don't. :) The challenge I find is getting the data into the computer. That's what a
by loxias 5y ago
> given that you need 16 decently high quality microphones...
But... you don't. :) The challenge I find is getting the data into the computer. That's what always costs the most. I've done it with 8x $1 mics and a used $100 sound card.
- cozzyd 5y agoCan't you buy a bunch of i2s microphones and use a cheap FPGA dev board with a USB interface?' I may just order a bunch of i2s microphones...
- loxias 5y agoCan one? Probably. Can I? Never done so before. Can you? :) I know enough EE to do simple things, about the amount you'd expect someone who's worked as a firmware engineer to know. The fact that you're saying "Can't you ... cheap..."? make me think this must be a viable path though. My hands shake too much for anything but the simplest soldering; is there a cheap FPGA board you'd recommend? And getting all the data into the computer... it could easily be ~70Mbps. (16 mics, 192/24) Making a custom USB class could be a mess, I wonder how hard it would be to just dump ethernet.
- cozzyd 5y agoCan I do right now... no but probably could figure it out :). I don't have any specific recommendations for a dev board, though a selection of some cheap dev boards is here: https://www.joelw.id.au/FPGA/CheapFPGADevelopmentBoards https://www.joelw.id.au/FPGA/CheapFPGADevelopmentBoards If you search around on Alibaba you can find some cheap dev boards that appear to have ethernet already (instead of you having to provide an ethernet PHY, which I think takes up something like 18 IOs?). Beware that even though most dev boards have a USB interface for programming it probably doesn't function as a USB for comms (i.e. you'd probably need to provide another USB PHY). Each I2S device probably requires 3 GPIOs. Someone who knows a lot more about this can probably make a much better recommendation. If you do the beamforming on the FPGA then you probably only need to output a lot less data that might be easily done over a simple UART. In the end, designing your own board with the right-size FPGA is probably the right solution, but that's only cheap per-unit in quantity and requires someone who more than sort of knows what they're doing. Though for someone who knows what they're doing it'd be a relatively quick project...
- causi 5y agoWhy in the world would you need to sample at rates that high? The quality of the audio is next to irrelevant, you just need amplitude and position.
- cozzyd 5y agoRight, it's not like the microphone probably has much of a response above 20 kHz and you can upsample while beamforming anyway .
- walrus01 5y agowhat $100 sound card has eight analog (TRS?) inputs?
- loxias 5y agoM-Audio Fast Track Ultra 8R. It's old. :) 8 in/8 out, class compliant, and has integrated preamps.
- rasz 5y agoCY7C68013A FX2LP can synchronously sample and transfer over USB 2.0 16 bits at up to 20MHZ. You can set it up with external IFCLK (5MHz minimum) and just pump data from 16 MEMS microphones to the PC all day long. $5 dev boards on ebay with free shipping. https://www.cypress.com/file/138911/download https://www.cypress.com/file/138911/download https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.732.853&rep=rep1&type=pdf https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.73...