It looks like I needed to change the decimation rate. Since cfile uses 16, I
tried 16 on the side of the demodulator (instead of 200, which is the
default), and it worked. Is this how it should be? One thing that does
happen is that it KILLS my computer's processing, which I assume the
throttle should help? I did this
self.connect (self.u, gr.throttle(gr.sizeof_gr_complex, 64000000),
chan_filt, self.guts, self.volume_control, audio_sink)
But while it works, it still is a bit sluggish, and a bit off. Any advice?
Sorry for the spam, it's always nice to have realizations...
2009/8/7 Jonathan Coveney <jcove...@gmail.com>
> Oops, it's attached now
>
> 2009/8/7 Jonathan Coveney <jcove...@gmail.com>
>
> So, the program will run, but instead of hearing anything, I just get oX
>> over and over again.
>> http://gnuradio.org/trac/wiki/UsrpFAQ/Gen#OUuainoutput
>> It doesn't look like a normal error, and doing a search, I haven't seen it
>> before.
>>
>> ./filesource_fmmod.py
>> >>> gr_fir_ccf: using SSE
>> >>> gr_fir_fff: using SSE
>> oXoXoXoXoXoXoXoXoXoXoXoXoXoX ad infinitum
>>
>> Anyone know what's up? I'll keep taking a look (and try adding a throttle,
>> for example). One possibility is that I had to manually set adc_rate, so I
>> set it to 64000000 (since it should grab a value of 64MS/s from the usrp, at
>> least according to the comment..and smaller values don't seem to work, so I
>> don't know)
>>
>> I've attached the changes I made... to make it easy to traverse, I simply
>> commented out existing code with a ##
>>
>> The code is usrp_wfm_rcv_nogui.py, modified to try and get a file source.
>> If you have any idea what that error means, or maybe where the code goes
>> wrong, your input would be appreciated (incidentally, what does the third
>> value in gr.file_source modify? the boolean)
>>
>> And a final question, when reading from a source obviously you don't have
>> to tune...but your samples were made over a given bandwidth, no? In my case,
>> I'm using the TVRX, so about 6MHz. if I want to do FM demodulation, do I
>> have to do it over the baseband? Or can I still "tune"? Is it just a matter
>> of shifting the baseband mathematically/
>>
>> Thanks
>>
>> PS if I can get this all working easily, would it be instructive to
>> include a basic nogui example that runs based on a file? It seems decidedly
>> nontrivial.
>>
>>
>> 2009/8/7 Johnathan Corgan <jcor...@corganenterprises.com>
>>
>> On Fri, Aug 7, 2009 at 12:49, Jonathan Coveney<jcove...@gmail.com> wrote:
>>>
>>> > I can't find one. The _cfile.py files will save samples to a file of my
>>> > specification, but I am trying to test using said samples, and not
>>> > succeeding. If it does not exist, I tried this:
>>> >
>>> > #self.u = usrp.source_c() # usrp is data
>>> source
>>> > self.u = gr.file_source(gr.sizeof_gr_complex, "data.dat",
>>> False)
>>> >
>>> > but there are a lot of things that I'm not sure how to manipulate, such
>>> as
>>> > the various rates that are usually drawn off the USRP, but in this case
>>> > don't necessarily apply because the samples are coming from a file?
>>> Maybe
>>> > they should just be set artificially to sort of trick the computer into
>>> > thinking that the samples ARe coming from a USRP?
>>>
>>> You're on the right track--continue to use gr.file_source. You'll
>>> need to comment out all the lines that try to set frequency, gain,
>>> etc. You can put them in a Python 'if' block and either run all the
>>> commands for the USRP, or just create the file source.
>>>
>>> The data is pulled from the file as fast as the computer can read the
>>> disk. If you want to play it back at a certain rate in wall clock
>>> time, you can insert a gr.throttle(itemsize, sample_rate) block in the
>>> pipeline.
>>>
>>> Johnathan
>>>
>>
>>
>
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