Re: [Discuss-gnuradio] Tx Burst for Chirp signals

[Yeo Jin Kuang Alvin (IA)]

Hi, 

Thanks Marcus! Corrected it and thanks for the info!

1)      I would like to transmit burst signals of the chirp generated  from the 
flowgraph attached. I tried using the “stream to Tagged stream” way, but when I 
ran the GNU Radio Companion, it’s being  transmitted continuously. Nothing 
seems to be happening. Am I doing  something wrong and is there a better way 
for burst transmission?

Does anyone know this?

Thanks in advanced!

-----Original Message-----
From: Müller, Marcus (CEL) [mailto:address@hidden 
Sent: Thursday, 10 May 2018 5:06 PM
To: Yeo Jin Kuang Alvin (IA); address@hidden
Subject: Re: [Discuss-gnuradio] Tx Burst for Chirp signals

Hi!

your receiver low pass filter is incorrectly parameterized, probably
(sampling rate isn't 32 MS/s). And so is the rest of your flow graph –
your USRP is using a sampling rate of 2 MS/s, but you act as if it's
running at 32 MS/s. Start with 2 MS/s and make it work with that – then
later scale up (the processing load of 32 MS/s is harder than you
probably think).
Remember that GNU Radio is pure DSP, so all the axis labels on your
visualizations are just that – labels, interpreting relative
frequencies (i.e. frequencies divided by the sampling rate) by
multiplying them with the value you entered in bandwidth. The "physical
meaning" of your signal is defined by the sampling rate of your
physical device.
Thus, you want to use the same sampling rate everywhere in your flow
graph. These things mean! something.

Best regards,
Marcus

On Thu, 2018-05-10 at 08:31 +0000, Yeo Jin Kuang Alvin (IA) wrote:
> Hi everyone,
>  
> There are two questions that I would like to ask.
>  
> 1)      I would like to transmit burst signals of the chirp generated
> from the flowgraph attached. I tried using the “stream to Tagged
> stream” way, but when I ran the GNU Radio Companion, it’s being
> transmitted continuously. Nothing seems to be happening. Am I doing
> something wrong and is there a better way for burst transmission?
>  
> 2)      I noticed something with the sampling rates of the blocks.
> When I use the same sampling rate for all the blocks, I get underflow
> “UUU”. However, when I changed all the block’s sampling rate to 32MHz
> and leave the USRP Sink and Source to 2MHz, no underflow is seen but
> there is still overflow (seen in the attached screenshot).
>  
> What is the difference between the USRP’s sampling rate compared to
> the other block’s sampling rate?
>  
> Thank you in advanced!
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio