Hi,
Thanks for the file! I am beginning to think that I have something wrong
with my Pluto since that does not work, either. I just get noise out. I
am going to try it on another pc later. I am running Ubuntu 17.04 under
VMWare since I don't really have any dedicated Linux machines. But, it
should work. I was able to get an RTL to "sort of" work a while ago,
although the audio quality was very poor with a lot of noise and breakup.
Regards,
Ed
On 12/18/2017 3:07 PM, Kyeong Su Shin wrote:
Dear Ed Troy:
Update: I was able to reproduce (..or maybe create a similar) problem
on an another computer; the problem was mainly due to buffer underrun
(may have to do with the data rate of the PlutoSDR source) . The
two-clock problem may also exist (but is not tested). There should be
a better fix, but as a quick & dirty fix, I just added a few delay
blocks to the flowgraph and it worked on that computer as well.
The flowgraph is attached. (Again, it is not a proper fix. Maybe you
want to look at better implementations, such as gqrx, or find more
appropriate ways to adjust the buffer..)
Regards,
Kyeong Su Shin
On Mon, Dec 18, 2017 at 1:41 AM, Kyeong Su Shin <kss...@uw.edu
<mailto:kss...@uw.edu>> wrote:
Dear Ed Troy:
(Also, it is not a simple flowgraph, but I heard that there is a
test build of GQRX for PlutoSDR (gr-iio based). You should be able
to use that to demodulate WBFM signals, if that is all you want..)
Regards,
Kyeong Su Shin
On Mon, Dec 18, 2017 at 1:34 AM, Kyeong Su Shin <kss...@uw.edu
<mailto:kss...@uw.edu>> wrote:
Dear Ed Troy:
Actually, I did re-test this with a PlutoSDR (I do have one
unit at home, although I do not usually carry this with me)
and your flowgraph worked on my PC + PlutoSDR once I reduced
the sampling rate from 5MS/s to 2.5MS/s (and adjusted the
decim ratio accordingly). Could you try different FM stations,
different antennas, or different GNU Radio installations
(maybe try running this on different computers)?
One other thing that I would check is the sampling rate that
the audio card supports. I know 96kS/s is usually an
acceptable value (and did work on my PC), but maybe you should
try 48kS/s instead.
I am also concerned about the two-clock problem between the PC
and the radio, but I still expect to get some audible sounds
even in the worst case scenario...
Regards,
Kyeong Su Shin
On Sun, Dec 17, 2017 at 9:08 AM, Ed Troy
<et...@aeroconsult.com <mailto:et...@aeroconsult.com>> wrote:
Hi Kyeong,
First, sorry about the double transmission of my message.
I did not attach [discuss-gnuradio] to the first one and
when I did not see it, I figured it got lost and so resent
with the correct subject line.
I have checked my board and it does seem to work down to
90 MHz. I need to run more detailed tests with a signal
generator to get exact sensitivity numbers, but it should
be good enough.
I tried making the changes to sample rate and other things
that you suggested, but it still does not demodulate FM
broadcast signals. I have to admit that the RTL-SDR
devices never did a very good job, either, but I
attributed that to relatively poor sensitivity, although I
have some pretty good ones, as far as they go. I also
tried to lower the gain, but that did not seem to work,
either.
If anyone has had success getting the Pluto to work with
FM broadcast signals, perhaps they could publish the grc file?
Regards,
Ed
On 12/15/2017 8:33 PM, Kyeong Su Shin wrote:
Dear Ed Troy:
I don't have the PlutoSDR with me right now, so I cannot
test it now, but a few things to check:
-Make sure that your Pluto can go down to 90MHz alright;
it is only rated to operate on 325MHz - 3.8GHz, and not
guaranteed to behave well on such frequencies (even when
you did made the changes).
-Try lower sampling rate; like 2MS/s. PlutoSDR is known
to drop samples at relatively high sampling rates (and
yes, I do mean that 5MS/s is too high).
-Try lowering gain; FM signals can easily overload the
frontend of such devices.
If I replace that PlutoSDR source block with an Osmocom
source block, change the carrier frequency to my local
station, and attach a different radio, it works. (Can't
test on a PlutoSDR now, as I do not have one with me now).
Regards,
Kyeong Su Shin
On Fri, Dec 15, 2017 at 4:12 PM, Ed Troy
<et...@aeroconsult.com <mailto:et...@aeroconsult.com>> wrote:
Hi,
I have been trying to get my Pluto to work with WBFM,
but I am not having any luck. I am attaching a grc
file that I am pretty sure should work, but it does
not. It just generates sporadic noise. I did the
changes recommended to get the Pluto to work over a
wider frequency range, and the results indicated that
the changes worked. And, I have tried using the Pluto
at higher frequencies to detect a WBFM signal, and it
still does not work properly. So, I know it has to be
something with my grc file.
What am I doing wrong?
Ed
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