Hi,
Thanks a lot for your reply!
This is exactly what I was looking for!
Would you by any chance have an idea in what C level files I could
manipulate the interpolation?
best regards and thank you,
Bjorn
Zitat von "Matthias Wilhelm" <wilh...@informatik.uni-kl.de>:
Hi,
i think this would be hard on the python level, you would need to
notify the python code after each symbol to make adjustments, which
will lead to latency between symbols ...
(As I understand you want to keep the chipping sequences, but change
the sampling rate used for each symbol. You can have the same effect
by changing the interpolation between samples, keeping the rate
constant, and oversampling small bandwidths. )
For this, I would suggest that you add a "per packet schedule" that
specifies the bandwidth of each symbol, and hack the C code to
follow the schedule, changing the interpolation between chips for
each symbol.
Something like send_802_15_4_pkt (packet, "1,2,8,2,4,1"), meaning
1MChips/s for the first symbol, 2MChips/s (the default) for the
second, then 8MChips/s, etc. The benefit is that you can go on
working on the packet level in python.
On the C side, you would need to run the flow graph at 16MSamples
(to get 2 samples per chip @ 8MChips/s, basically fast enough to
support the largest bandwidth you want), and decide for each symbol
the necessary interpolation to generate the specified bandwidth
(e.g., 16 samples/chip @1MChips/s).
Regards,
Matthias
Am 27.07.2011 um 13:31 schrieb bjoe...@ee.ethz.ch:
Hi,
I'm currently using the UCLA ZigBee Phy implementation by Thomas
Schmid and I need to
change the Bandwidth of the used wireless channel on a per symbol basis.
I managed to change it on a per packet basis, which can be done on
the python level
(tunnel.py, usrp_transmit_path.py etc.). Well now, I need to do the
same thing, but on a
per symbol basis, which (up to my knowledge) is not possible from
the python level...
Does anyone have an idea how I could do that? (Changing the Bitrate
of the USRP after
each symbol (e.g. after sending 32 modulated bits (actually chips)))
I would be very happy for any help or suggestions!
Thanks a lot!
best regards,
Bjorn
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