About 'internal AGC'

Leif Asbrink leif at sm5bsz.com
Sat Aug 17 23:10:49 UTC 2013


On Wed, 14 Aug 2013 19:55:03 -0700 (PDT)
m240zz at gmail.com wrote:

>  The thing that confuses me is why is it during the sweeps due the fft look 
> so different in each of the windows  and it seems like the timing of the 
> sweeps are different.  The sweeps happen at the same time for each dongle, 
> right?  The dongles  are all listening in parallel at the same time?  If 
> so, seems like they would look more alike at the same time.  My apologies 
> for the density on this end.

The purpose of the vido was to demonstrate that dongles are different.
The sweeps indeed happen at the same time for all the dongles. The very
point is that they do not look very much alike. It is non-trivial
to know in advance which one will perform best in a real life
situation.

It was the first video. It just shows that dongles are (very) different.
I am uploading some more videos as a response to the feedback I received
so far. (Upload is extremely slow from here...)

It would be trivial, but it would take a lot of time, to use a dongle
to provide a wideband map from 50 to 500 MHz or whatever on a particular
antenna in a particular location. With that knowledge it would be easier to
decide what dongle to choose for a particular situation. It is trivial
to add a selective filter and that can make a big difference for the
dongles.

73

Leif






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