Re: [Discuss-gnuradio] python/digital examples and UHD

[Moritz Fischer]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 11/29/2010 03:47 PM, Tom Rondeau wrote:

Thanks for your reply Tom,

>> Have you used the version 2 digital code, yet (benchmark_tx2,
>> benchmark_rx2, usrp_receive_path2, etc.)? One of the things I did was
>> include better resampling so that you can get any bit rate you want.
>> You still have to go through the process of selecting the USRP's
>> sample rate that's closest to your desired rate, and then the
>> resampling takes care of the rest.

Well in fact that's what I was looking at. I called this the
'automagical' frequency selection in my last mail ;-)

It appears to me you do this by trying all the tuples of (bitrate,
samples_per_symbol,...) and select the one fitting 'best'.

So please don't throw stones at me for asking this question, but from my
understanding the required

desired_samplerate = bitrate x samples_per_symbol / bits_per_symbol (1)


>> What I do with the UHD driver is ask for a sample rate. It will then
>> set its sample rate to whatever the closest rate it can do. You can
>> the read back the actual sample rate of the USRP with get_samp_rate().
>> I then use this value to determine the difference between my desired
>> sample rate and the actual sample rate, which I then plug into the
>> arbitrary resampler.

So what you suggest is basically:

1. set_samp_rate(desired_samplerate) as in (1)

2. tmp = get_samp_rate()

3. and then resample in gnuradio according to tmp / desired_samplerate

or did I get something wrong?

Please don't get me wrong because I ask a lot of questions :-)
I don't ask you guys to do any of my work (like a thesis or the likes).
Just in my opinion having the examples working is really important,
because that's where new people start to look at when trying to figure
out how stuff works.
And nothing is more frustrating than not even managing to get the
examples running.

Best regards and happy hacking,

Moritz



-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)

iQIcBAEBAgAGBQJM9L5tAAoJEOjnDXL6I0uZtNwP/1JDIggYhvBRw6bJQmQzUjKU
mDKrYyqIdFbLDv0+aC62gTn0g+OVpa11yP585pZcF9tZ5A9ZwIqSEpo6iEPXH883
q6+A3GmogTAqtaydf7seG3PkdV/HXZcAkBRtd0QgjMykKbIOG2hlDTJZsv8Ru0Iz
/dOa6ERrxHQSrYY1DLW/e5dMrwBp8SMGdIT3RlwpuKvQyZmA9xj8rcqxNyvfHuNf
3KT5AFCQQbKrmGXiwb9z+09rFTHWga4hdLbfkX+L4ANz/j2eUDxomLgSVcx1vOEb
0Qqn1MJu2vBRceIdyiAItl3gnocWZ62EQMnvIcoDY9F7Mi9sBCWVV18CWVwPv2SU
P+4o5wRvpV5b7nVn6U0Yi47w0/Wfz5UsYbiGMc/scrpSa0wHuYv7BXsjlOOANrmd
RAYz0Xvk6aIq4P4RuuqeIx1AWfw0tLcQaO7BAAvanZqf6qf+HqP+oMmCQZgWzlhL
hgDuL/7YdpUN66c8xSXivCfFZpf/FOkoKMhF1N7BQ1EM349BrgbPdL3VO0I/jEs/
f7nsMML7FkhJdOF5IH/1QgEl+fGGMNvEmqBqfm3w/pYtUkwX4KDnc6GrHimYrk72
QnFuv2ZWURnyNsvp7pYnH27Bu7ssyYa6DZP+Iu047Ev7iK0oMuqaQaWxDibSSL4c
vMqE5g//R0SsNBcTtiZe
=x5g+
-----END PGP SIGNATURE-----