Thanks-
I just downloaded, compiled and installed this latest revision. When I
test multi_scope.py in the mutli-antenna examples directory with this
release I get the same issue. Please note, I have the LF_RX
daughterboards, so I change the daughterboard ID from BASIC to LF in the
python code. I also eliminate the second factor of 4 decimation in the
host (sw_decim = 4) by setting it to 1. I then run with the following
command:
multi-antenna]$ ./multi_scope.py -f0 -d250 -g0
while acquiring a 10 kHz 0.3 V p-p signal. The max value shown in the
waveform on the gui is just over 25,000, which is way too much compared to
the standard usrp_fft.py, which by the way is no longer in the examples
directory; I used one from a previous release. If I increase the input
voltage level to 0.4 V p-p, I get a jagged waveform with sharp
discontinuities.
So, my problem remains. Any ideas?
thanks,
eric
On Tue, 9 Oct 2007, Eric Blossom wrote:
On Tue, Oct 09, 2007 at 03:02:33PM -0400, [EMAIL PROTECTED] wrote:
Thanks so much for clarifying that! I see now that config.vh controls how
the code is configured.
FYI, I've committed new rbfs to the trunk. They were built with
Quartus II Web Edition, version 7.1 SP1
Regarding the loss of the half-band filters in the multi-antenna fpga
configuration; what is the recommendation to avoid aliasing? Say for the
case of a 2 MHz carrier AM waveform with modulation out to 100 kHz. What
kind of filtering would I need to avoid aliasing?
thanks again,
eric
With the halfbands, it's flat to about 70% of the passband.
decim = 320 gives 200kS/s complex baseband, a bit more than you'll
need.
Without the halfbands, I'd use about 4x the bandwidth of interest,
then filter and decimate in the host for the final channel selection.
In your case, I'd use decim = 160 giving 400kS/s.
Eric
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