Re: [Discuss-gnuradio] Delay determination between Tx and Rx signal for limesdr mini with help of gnu radio.

[CEL]

Dear Atiqur,

my concerns are less of the GRC variant, but of the DSP variant:

* If your GRC doesn't complain about you using Throttle together with
the hardware blocks, that's a bug in the hardware blocks. Anyway, NEVER
use Throttle with hardware blocks. You incur the two-clock problem, and
will run into overflows/underruns. You can't see that with a GNU Radio-
internal visualization. More info under [1].

* Your sampling rate is laughably low for SDR applications, which is
why I presume that the LimeSDR doesn't support sampling rates that are
so low.

* No matter what you say, an equalizer and a timing/phase recovery is
something to be done on the *receive* side, not on the transmit side. 

Best regards,
Marcus

[1] 
https://wiki.gnuradio.org/index.php/FAQ#When_do_I_use_a_throttle_block.3F
On Mon, 2019-07-15 at 17:40 +0200, Md. Atiqur Rahman wrote:
> Dear  Marcus, 
> Thank you for your quick reply.
> 
> Actually, I am very much new in GRC. The GRC is running without giving me any 
> error though. If I use 32KS/s, it stopped working by saying python stop 
> working. Therefore, I am giving 64KS/s.
> 
> I am following the grc-tutorial, hence that modulation scheme contains 
> equalizer and timing recovery on the transmit side. Shouldn't I use it? 
> please correct me if I am wrong. 
> 
> Sincerely,
> Atiqur
> 
> On Mon, Jul 15, 2019 at 5:05 PM Müller, Marcus (CEL) <address@hidden> wrote:
> > Oh, and why are you doing an equalizer and a timing recovery on the
> > *transmit* side!?
> > 
> > On Mon, 2019-07-15 at 15:04 +0000, Müller, Marcus (CEL) wrote:
> > > Also, without knowing, I'm almost certain that 64kS/s is not a possible
> > > sampling rate for the device. You really might want to read the console
> > > output very closely!
> > > On Mon, 2019-07-15 at 14:56 +0000, Müller, Marcus (CEL) wrote:
> > > > So, first of all: 
> > > > 
> > > > never use "Throttle" in a flow graph with hardware. 
> > > > In fact, GRC will *scream* at you that you shouldn't be doing that! 
> > > > 
> > > > Then: I can't claim to have any knowledge of the limeSDR driver, but
> > > > unless that driver specifically allows you to start the TX and RX
> > > > streaming at the exact same instance: That delay is not a deterministic
> > > > value.
> > > > 
> > > > Best regards,
> > > > Marcus
> > > > 
> > > > On Mon, 2019-07-15 at 16:46 +0200, Md. Atiqur Rahman wrote:
> > > > > Hello Guys, I am having trouble to find the proper delay point 
> > > > > between Rx and Tx signal while running the qpsk modulation scheme on 
> > > > > gnu radio to my Limesdr mini board. While I am running the program 
> > > > > through limesdr, I realize that it has a greater delay between (as 
> > > > > expected). However, until now I am unable to find the proper amount 
> > > > > of delay. I am changing the range of the delay from gui range(int 
> > > > > type) to find the delay which will give me the synchronized Rx and Tx 
> > > > > so that I could ensure that there is no missing data at the receiver 
> > > > > side. 
> > > > > 
> > > > > I attach the file here in this email. Hope anybody would like to 
> > > > > help. Thanks in advance.
> > > > > 
> > > > > Sincerely,
> > > > >  Atiqur 
> > > > > 
> > > > > _______________________________________________
> > > > > Discuss-gnuradio mailing list
> > > > > address@hidden
> > > > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > > > 
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> 
>

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