|Subject:||Re: [Discuss-gnuradio] Losing sample count integrity / Source(s) slipping ?|
|Date:||Sat, 5 Dec 2015 11:48:58 +0100|
|User-agent:||Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0|
first of all: Nice flowgraph! I especially like this part:
to give you a single 1 every 1000 samples; I'd never come up with this!
Also, from looking at this, I'd say you're a digital designer; how far am I off? 
So, to your actual problem: I guess you're right, there's a problem with numerical accuracy.
I made a quick demo flow graph:
which, in theory, should be output constant 1, but instead shows the slow drifting.
I do think this is in the range of what I'd expect of numerical accuracy, but as I don't have the time to test this right now, I'm attaching my test flow graph. The right thing to do would be calculating the angular speed of the output and see how large it is compared to the angular precision of float32 put through cos(.).
 My much more signal-theoretic approach would have been this:
i.e. interpolating a stream of 1s with a filter that isn't actually doing anything, i.e. has "" as taps.
Or, even shorter:
because GRC / python allows us to just specify a vector that we sample.
On 05.12.2015 06:15, Tom McDermott wrote:
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