How to make microphone array with 192 kHz sampling
Posted: Fri Aug 31, 2018 4:59 pm
I am looking for a way to make a mic array, but I need the high sampling rate of 192 kHz.
Initially, I don't mind the configuration of the microphone array,
but at a later stage, I might want to change the number of mics (e.g. to 16 or 32) or the spacing between them.
-- Scenario 1--
The xCORE Array Microphone [USB] [https://www.xmos.com/support/boards?product=20258]
seems like a good start, but:
- It is limited to sampling frequency of 48 kHz.
- If I need to change number of channels, I'll need to move to another platform
Problem to solve:
- Get the device to sample at 192 kHz.
What I checked:
I looked in the documentation of the lib_mic_array library [https://www.xmos.com/download/private/l ... rc1%29.pdf]
and found that the final output at 48 kHz is a result of several decimations.
p. 10 of the user guide says that "Each delay line sample is clocked at the PDM clock rate divided by 8, that is, 384kHz for a 3.072MHz PDM clock"
Then the decimators are applied until the sampling frequency is reduced to the one of: 8, 12, 16, 24 or 48kHz
Question 1:
- Is it possible to somehow hack into the thing and get the 192 kHz of sampling.
-- Scenario 2--
The xCORE-200 Multichannel Audio Platform [https://www.xmos.com/support/boards?product=18334]
seems to solve the problem with the sampling frequency
as it provides 8 channels analog input coming out as PCM 384kHz at 16, 24 or 32 bits.
But if i need to increase the number of channels, I would need to use a couple of boards and find a way to synchronize the acquisition.
Question 2:
- Is it possible to synchronize the acquisition from several xCORE-200 Multichannel Audio Platform boards? How?
Thanks for any pointers
Initially, I don't mind the configuration of the microphone array,
but at a later stage, I might want to change the number of mics (e.g. to 16 or 32) or the spacing between them.
-- Scenario 1--
The xCORE Array Microphone [USB] [https://www.xmos.com/support/boards?product=20258]
seems like a good start, but:
- It is limited to sampling frequency of 48 kHz.
- If I need to change number of channels, I'll need to move to another platform
Problem to solve:
- Get the device to sample at 192 kHz.
What I checked:
I looked in the documentation of the lib_mic_array library [https://www.xmos.com/download/private/l ... rc1%29.pdf]
and found that the final output at 48 kHz is a result of several decimations.
p. 10 of the user guide says that "Each delay line sample is clocked at the PDM clock rate divided by 8, that is, 384kHz for a 3.072MHz PDM clock"
Then the decimators are applied until the sampling frequency is reduced to the one of: 8, 12, 16, 24 or 48kHz
Question 1:
- Is it possible to somehow hack into the thing and get the 192 kHz of sampling.
-- Scenario 2--
The xCORE-200 Multichannel Audio Platform [https://www.xmos.com/support/boards?product=18334]
seems to solve the problem with the sampling frequency
as it provides 8 channels analog input coming out as PCM 384kHz at 16, 24 or 32 bits.
But if i need to increase the number of channels, I would need to use a couple of boards and find a way to synchronize the acquisition.
Question 2:
- Is it possible to synchronize the acquisition from several xCORE-200 Multichannel Audio Platform boards? How?
Thanks for any pointers