Two Sound Level Meters

We now have support for two more sound level meters in libsigrok. Both can do live streaming, and do standalone logging for later retrieval.

First is the CEM DT-8852, a large handheld unit. It has all the usual features you'd expect in a sound level meter, and claims IEC 61672-1 Class 2 compliance. Particularly interesting is the fact that it can stream its dB measurements to the host at 20Hz; this sort of device generally streams at 1 or 2Hz.

The firmware is somewhat... temperamental. It was a particular challenge getting the driver to control settings on the device. The vendor software typically takes between 0.1 and 10 seconds before changing a setting actually takes effect on the hardware. The sigrok driver does considerably better: it's reliably under 1.5 seconds, and usually much faster. It all works very well now: the sigrok driver has workarounds for all known bugs.

The second new SLM driver is for the Kecheng KC-330B. It has a "USB stick" form factor, and so is intended mostly for standalone logging. It doesn't work very well: logging can only be started manually, by pressing the button, and even then it's not so sure to actually work. The sigrok driver only supports streaming from this device for that reason: the data logging functionality on the device is just too unreliable.