[USRP-users] N210 WBX annoying spurs while switching

Ian Buckley ianb at ionconcepts.com
Thu Oct 23 01:19:08 EDT 2014


It's more than just padding your signal with zero's…you need to ramp the amplitude of your signal to/from zero over a period of time in a fashion that minimizes the spectral artifacts otherwise created.

On Oct 22, 2014, at 10:08 PM, bob wole via USRP-users <usrp-users at lists.ettus.com> wrote:

> So you are suggesting that I should zero pad samples at start and end of my burst to avoid this ? 
> 
> On Wed, Oct 22, 2014 at 9:16 PM, Matt Ettus <matt at ettus.com> wrote:
> 
> When you start and stop transmission without smoothly ramping the signal to zero at the beginning and end, you will create wideband spurs.  Just think about it as amplitude modulation.  Even if you are transmitting a pure sine wave, if you turn it on and off quickly, it will create out of band spurs.  Hams call this keyclicks.
> 
> Matt
> 
> 
> On Wed, Oct 22, 2014 at 1:25 AM, bob wole via USRP-users <usrp-users at lists.ettus.com> wrote:
> I noticed that there are a lot of significant spurs generated in the output of WBX, on different frequencies randomly, when I use tx_time, tx_sob_tx_eob tags. I do not see these spurs if I transmit continuously. These spurs appears only when I start and stop transmission using stream tags. 
> How can I get rid of these spurs and what is the cause?
> 
> -
> Bob
> 
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