Bruce Griffiths wrote:
If one has a high end sound card then it could be used to implement the
bandpass filter and replace the zero crossing detector.
It may be necessary to insert a pilot tone to calibrate the sound card
sampling clock frequency.
A noise floor of about 1E-13/Tau should be achievable.
This simplifies the DMTD system by replacing the zero crossing detector
with a low gain linear preamp.
If one analyses the resultant data off line then one can also try out
different techniques such as a Costas receiver rather than a simple
bandpass filter plus zero crossing detector.
However 1000 seconds of data for 2 channels of 24 bit samples at 192KSPS
will result in a file with a size of at least 1.15GB.
First step would be to implement a real-time first-line receiver
processing. Should not be too hard. Costas-loop isn't too complex to
implement, but for full repeatability using the same signals for
different set of parameters... but then again, it is fairly
straight-forward to implement.
Using either a separate channel or FDM a reference 1 kHz (from say
TADD-2 divider) should work for reference tone. A good board can be
word-clock locked without too much hazzle.
Not too happy about the quality of the real-time spectrum apps I have seen.
Cheers,
Magnus
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