Re: [Discuss-gnuradio] how to manage time!

[Marcus Müller]

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

Hi Mostafa,

you will have to have all your sample streams at the same nominal
sampling rate (which again has nothing to do with the item rate you
described). You do that by resampling.

How you combine these streams is obviously totally part of what your
application has to define.

Greetings,
Marcus

On 09.05.2014 08:14, Mostafa Alizadeh wrote:
> Hi Marcus,
> 
> I actually want to implement a transmitter. So in this transmitter 
> different data streams come from different sources with different
> rates (or sample rates). Then all of these streams gather together
> in a block, may I call it "Collector" then it sends the gathered
> data stream to the USRP sink. The *Collector* block should gather
> the data stream in some specific manner to put the streams in a
> particular frame!
> 
> The only thing I don't know here is how could I generate these 
> different-rate data?
> 
> At the receiver we don't have any problem like this one, I think,
> because we can set the sample rate for USRP then after detection of
> the data streams in the *frame* we actually could find the 
> transmitted-dirfferent-rate streams with different rate. :)
> 
> Any idea please?
> 
> best,
> 
> 
> On Fri, May 9, 2014 at 12:23 AM, Marcus Müller
> <address@hidden>wrote:
> 
>> hi Mostafa,
>> 
>> a fixed item rate just happens coincidentally when using actual
>> hardware. In digital signal processing you really usually don't
>> care, as long as latency constraints are met. typically, you
>> can't even do that at all, because GNU Radio blocks tend to
>> process samples en block.
>> 
>> maybe tell us a little bit why you want to have a physical item
>> rate, things would clear up a bit:-)
>> 
>> greetings, Marcus
>> 
>> 
>> On May 8, 2014 9:37:32 PM CEST, Mostafa Alizadeh
>> <address@hidden> wrote:
>>> 
>>> Hi Marcus, I did know about the Throttle block and which
>>> doesn't do anything with data just control its passing. My
>>> question is how to generate a bit stream(I say bit and we could
>>> simply call it item), say random, with specific sample rate
>>> just as audio source do! I had a glimpse at the source code of
>>> *portaudio_source.cc *in gnuradio files but I didn't find out
>>> it easy to understand. :(
>>> 
>>> any idea?
>>> 
>>> best,
>>> 
>>> 
>>> 
>>> On Thu, May 8, 2014 at 10:03 PM, Marcus Müller
>>> <address@hidden>wrote:
>>> 
>>>> Hi Mostafa,
>>>> 
>>>> I'm not really sure I understand your question: there is
>>>> different "times" in DSP: 1. the times relative to the
>>>> "information theoretical world", which increases with
>>>> 1/f_sample per sample 2. the time relative to the computing
>>>> machine, which just runs along while the computer is busy
>>>> computing
>>>> 
>>>> Throttle is *explicitely* just a throttle block. For a
>>>> *purely simulating* flowgraph, you can use it to *limit CPU
>>>> usage*. it has no other purpose. It is a very very rough
>>>> mapping of the first time to the second one. It really has no
>>>> data effect. I emphasisize this, because that mistake is made
>>>> so often: it does not change the samples at all. it just
>>>> limits the speed they are processed with.
>>>> 
>>>> I think your question is "I want to have a sample stream that
>>>> contains 1000 bits of information for each second worth of
>>>> samples". So you have to calculate how many samples you have
>>>> per bit at your specified sampling rate and use that.
>>>> 
>>>> Since you write "I saw the trottle block but I don't know
>>>> what it does", I think you can learn interesting things by
>>>> working through the Tutorials on 
>>>> http://gnuradio.org/redmine/projects/gnuradio/wiki/Tutorials
>>>> from top to bottom. This will clear up a lot of things!
>>>> 
>>>> Greetings, Marcus
>>>> 
>>>> On 08.05.2014 19:24, Mostafa Alizadeh wrote:
>>>>> Hello everybody, I want to have a block of, for example,
>>>>> bit generator, which generates
>>>> 1000
>>>>> bps. How could I manage the time in a thread (or
>>>>> equivalently in a
>>>> block)??
>>>>> *Or saying in general, how could I manage timing for
>>>>> passing data
>>>> between
>>>>> blocks!?*
>>>>> 
>>>>> I saw the "Throttle" block of gnuradio in c++ but I didn't
>>>>> how it
>>>> works!!
>>>>> 
>>>>> best,
>>>>> 
>>>>> 
>>>>> 
>>>>> _______________________________________________ 
>>>>> Discuss-gnuradio mailing list address@hidden 
>>>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>>>>> 
>>>> 
>>>> _______________________________________________ 
>>>> Discuss-gnuradio mailing list address@hidden 
>>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>>>> 
>>> 
>>> 
>> -- Sent from my Android device with K-9 Mail. Please excuse my
>> brevity.
>> 
> 
> 
> 
> _______________________________________________ Discuss-gnuradio
> mailing list address@hidden 
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> 
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1
Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/

iQEcBAEBAgAGBQJTbICZAAoJEBQ6EdjyzlHty44IAIPwu9yqultka/oTr5zQq/IY
BlI+b9EE7KXUaxzsjLst1puw0ckiQ5RoDY/fXr9eA+DV9HBGgCFtwCobkn4MTLm0
aKU7DEpJfVpGDhFSmTA9Q/7EJupprccvK9AR4MC8zKx/WyS8avQk+9kJaeeDw7CZ
R94CH/whUDrfyeLLMyzc2cXQMEdHEBj5dqfi9ybNw2EgtsxXM/urBBgK/hTbucvA
sWFcJTD3h3aOKold/Kjn8ksGDmjrfIs5Ym/We62h+sUS+DKDHX3/AnEHA2p7pFGc
9CgxPfTUs6LYKYxogzyoQnx1DtaNVrDq6gI//YceT8WLV4ADTY4xK5U+B8ABjpo=
=2SWS
-----END PGP SIGNATURE-----