Hi Hans,
> It's 6dB per bit. So 45dB would be 7.5 bits. Not 15.
You're right, of course, about the 6dB per bit.
But I think Audacity may be confusing things a bit (seems to me that Audacity is off by a factor of 2).
Let's look at it a different way.
The maximum absolute value of the samples in the 24-bit PCM wave file recorded on the QMX is 389.
Therefore the entire wave file has a 10 bit dynamic range (all values fall within [-512,511] so are representable using 10 bit signed integers).
That leaves us with 14 bits to spare.
So there really is a lot of headroom here.
Whether or not we are missing FT8 decodes due to quantization error depends on the RF noise floor as well as quantization noise floor.
But it sure seems possible to me that we could be missing decoding some of the weaker signals.
I'd love to know the dynamic range you and others are seeing on the QMX with default gain of 54.
My Windows audio device gain is set to 100% for the QMX audio device.
I'll play around with the gain value in the QMX configuration screen and report back.
73, Mike KK7ER
