2019-04-01 06:12 AM
Hi,
I would like to have some help understanding what the measurements that i can get from the
SoundMesauRments library provided in cube actually are. What does the calculated dB's actually relate to? What is 0dB in the scale?
My setup is a mems mic connected through i2s which are sampled an feed into the SMR library.
Kind Regards
Daniel Moberg
2019-04-05 02:32 AM
Hi @Daniel Moberg ,
Did you checked the UM2031 (Sound meter library software expansion for STM32Cube) to look for answers to your questions?
-Amel
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2019-04-08 01:51 AM
Hi, Yes i have checked the UM2031.
Some more details:
I am using V1.0.5 version of the SMR library, (Version taken from the smr_glo.h)
My target is the STM32F411RET
I have dumped the PCM data from the Microphone and played it on my computer and the mic data seems fine.
When i disable the prefilter using filter none I get more reasonable output. Leading me to suspect the pre-filter.
I have tested all the pre-filters, And they do no seam to react much compared to a handhold db meter.
My setup looks like below:
smr_static_param_t params;
params.sampling_rate = 48000;
err = smr_setParam(¶ms, &m_smr.memory);
smr_dynamic_param_t dynamic_params;
dynamic_params.averaging_time = 1000; // ms
dynamic_params.enable = 1;
//dynamic_params.filter_type = SMR_PREFILTER_NONE;
//dynamic_params.filter_type = SMR_PREFILTER_DCREMOVE;
dynamic_params.filter_type = SMR_PREFILTER_AWEIGHTING;
//dynamic_params.filter_type = SMR_PREFILTER_CWEIGHTING;
err = smr_setConfig(&dynamic_params, &m_smr.memory);
Can you provide some code that can verify the the library?
Kind Regards
Daniel Moberg
2019-04-08 11:13 PM
See answer below. (Posted answer instead of reply)
Kind Regards
Daniel Moberg
2024-08-01 10:11 AM
yes, but why I can find the library ?