On Tue, Aug 31, 2021 at 02:14 AM, Erik Kaashoek wrote:
Reg,
What Roger tried to says is that the tinySA has NO flexibility in defining the
shape of the filters as the DSP processing is fixed (apart from limited
parameters), there are no resources to do processing before the filters and
there is no way to extract the unprocessed data.
So the only way is to take many measurements and apply some form of post
processing on the measurement data.
If you know how to do that within acceptable time and with acceptable
resources that would be most welcome.
------------------------------------------
For more info on the tinySA go to
I spent a large part of the day reading the 334x datasheet. Here is how you implement sidelobe suppression on the existing HW:
read RSSI as rapidly as possible until either N*dT > 1/RBW or satisfactory suppression is achieved. We are in sampled space. There is no escape.
apply the desired window function sample weights to the samples and accumulate
output corrected sample with sidelobes suppressed.
I should note that there is no requirement that all of the data be real. One may interpolate additional samples with appropriate attention. Simon Spitz became very famous in the seismic community for figuring out the first of now several ways of doing that.
Where in the source is the signal strength being read? So far I've not been able to determine how fast RSSI can be read. Have you measured that?
On a separate subject, the best RBW that the 4432 can achieve is 156.25 Hz or 312.5 Hz (lo & hi). There are 3 basic methods for improving the resolution, Wiener, Fourier and sparse L1 decon. For the tinySA FW, Wiener is the obvious choice for resolution enhancement. Aside from resolutions < 3 kHz, it is only needed to implement RBW options other than those already present. The sampling sidelobes should be dealt with as outlined earlier with a range of window choices (hint: device with more storage). There are many windows because there are many use cases with different objectives.
Have Fun!
Reg
