Bedrock SM30, Руководство по эксплуатации

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62 Bedrock SMxx operating manual © Bedrock Audio BV, 2019
63
10.4. USB audio device mode
When starting this module, a special mode of the device is activated, in which it performs
no other tasks than simply streaming audio to a PC while applying the SMxx’s level calibra-
tion. This is done in the form of a single-channel stream, at a fixed bandwidth of 48 kHz
and a bit depth of 32 bits. All current versions of MS Windows should recognize the SMxx
while operating in this mode as a “USB audio device” and may also indicate that it is an
“omnidirectional microphone.” Once the device is detected by Windows, make sure that
the software that you intend to use is also configured for the device. A small Windows test
application is included on the USB flash drive that came bundled with your Bedrock SMxx.
The SM50 display while in USB audio mode
Once the device is connected via USB (and the PC has recognized it as an audio device), an
indication showing “USB connected” will appear. Once data starts streaming, an animated
picture and the message “data link active” will indicate that data is being transferred. This
will happen once an application initiates streaming audio from the Bedrock SMxx.
The audio signal is scaled so that full scale corresponds to 150 dB (e.g, a signal with a level
of 94 dB will correspond to a level of -56dB relative to full scale). Windows drivers and ap-
plications may digitally adjust the level by applying software-based volume settings. If left
unadjusted, the volume of the signal when directly played back on the PC may be quite low.
This is done on purpose, so that high levels of up to 150 dB can be accommodated. Given
the fact that 32-bit audio has a dynamic range of 192 dB, this does not affect the integrity of
even the lowest-level signals. The entire dynamic range of the Bedrock SMxx is available
digitally. If the audio is too soft, simply adjust the volume control on the PC.
If you want to explicitly calibrate your windows software to work with the Bedrock SMxx,
press the “cal” button to generate a synthetic 1000Hz sine at 94.0 dB. If you calibrate your
software to this level, then all audio measured by the SMxx will be registered at the correct
levels in your software as well. Press “mic” to return to normal operation.