On 30/09/2023 10:33, Devin Kelly wrote:
Marcus,
I think I forgot to attach the second screen cap (see below).
Is it possible to just leave the TX chain on? I'm sending many pulses
rapidly so it doesn't make sense to turn it on and off so much.
Devin
image.png
On Fri, Sep 29, 2023 at 6:43 PM Marcus D. Leech
<patchvonbr...@gmail.com> wrote:
On 29/09/2023 17:14, Devin Kelly wrote:
All,
I’ve noticed some odd behavior when transmitting bursts on a B210
and B205mini. When scheduling my bursts there’s a big “blip”
before my desired signal. I eventually started looking at
tx_bursts.cpp and was able to re-create the “blip”using this command:
./tx_bursts --repeat --rep-delay 0.01 --gain 50 --dilv
Though pretty much every command had the “blip.” I’ve attached
some oscilloscope screen caps below. My desired signal starts
around 977 ns. This is with UHD 4.4 and the “blip” happens on
every burst (the second screep cap shows this but it’s hard to see).
I’ve also noticed that the blip magnitude stays the same and if I
increase the gain where the rest of the signal increases or
decreases.
How do I make this go away?? I’ve tried pre-pending 0s to my
signal and fiddling with pretty much every MultiUSRP setter.
Thanks!
Devin
I can't really see details in the plot you attached, but my guess
is that this is just the turn-on transient of the RF power amplifier
chain. Not sure there's much you can do to get rid of it if
you're sending TX bursts, since the TX hardware has to be turned
on/off between bursts.
For a test, you could put your burst waveform in a file, and use
tx_samples_from_file with the --repeat option, and see what the
behavior is. My guess is you'll get the TX-on transient at the very
start, and the rest will be smooth sailing.
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