Hi Tom,
Thanks for your help. I’ve adapted the sample rate of the result coming
out of the low-pass filter now. However, if I decimate much further, my
signal becomes a bit too weak I think.
New chart:
http://imgur.com/mbt288s,etHbYLT#0
New result:
http://imgur.com/mbt288s,etHbYLT#1
Is this a better approach?
The initial error still persists though.
Regards
From: [email protected]
To: [email protected]
Date: Thu, 20 Aug 2015 09:09:42 +0200
CC: [email protected]
Subject: Re: [Discuss-gnuradio] GnuRadio: Clock Recovery MM: imu out of
bounds
Hi Tom,
Thanks for your answer. That’s indeed something that I need to think
about more. However, as I understand it, the samples per symbol rate is
equal to (samp_rate / data_rate). My sample rate is 500k, and my data
rate (i think) is only around 100 or 200. See this figure of my
(cleaned) signal:
http://imgur.com/8pNqCop
You see that it takes approximately 10 ms to transmit one symbol. This
means 100 symbols per second. As I have 500k samples per second, this
means 5k samples per symbol, right?
However, I have tried setting the samples per symbol to 4, just to try,
and the ‘out of bounds’ error still persists.
Regards,
Michael
From: [email protected]
Date: Wed, 19 Aug 2015 09:41:19 -0400
Subject: Re: [Discuss-gnuradio] GnuRadio: Clock Recovery MM: imu out of
bounds
To: [email protected]
CC: [email protected]
On Wed, Aug 19, 2015 at 2:51 AM, Michael B [email protected] wrote:
I have created a flowgraph, based on an example of Michael O.,
which takes in a signal, and should output bits.I need to use the clock
recovery MM block, which I do not fully understand yet. However, after
reading some blogposts, I am quite sure that I can leave most of the
settings default, except for the Omega one. Here’s my flowgraph:
http://imgur.com/pHRXnZu
When running this flowgraph, it gives me the following error:
thread[thread-per-block[5]:<block clock_recovery_mm_ff (9)>]:
mmse_fir_interpolator_ff: imu out of bounds.
While searching, I stumbled upon this piece of code in the source of
GnuRadio:
int imu = (int)rint(mu * NSTEPS);
if((imu < 0) || (imu > NSTEPS)) {
throw std::runtime_error(“mmse_fir_interpolator_ff: imu out of
bounds.\n”);
}
So, I suspect it is not due to my Omega setting (which might be wrong, I
have to play with that setting), but that it is due to my Mu setting,
which is just the default (0.5). However, I understand that Mu needs to
be between 0 and 1, so I do not really understand what the problem is.
Anyone who does?Environment details:GNU Radio Companion 3.7.7.1Running a
GNU Radio live DVD in a virtual machine (VirtualBox 4.2.12) on Windows
7.Using Volk machine: ssse3_64
Michael,
I don’t have an answer, but I can say where you’re doing something
wrong. You’re samples/symbol (samp_per_sym) is definitely /not/ 2.5k.
That’s a massively oversampled signal and can’t be right. You need to
think what’s the sampling rate of the system? What’s the symbol rate of
my signal? That will tell you the samples/symbol you need. It should
small, like 2 or 4.
Tom