Re: [Discuss-gnuradio] The shortest pulse length

[Lee Patton]

On Mon, 2007-02-26 at 00:55 -0800, seph 004 wrote:

> I have a vector source producing a sine wave, and then I'm using
> gr.head to limit the number of samples sent. 

I'm sure you checked this, but are you trying to capture the first few
samples of sin(x)?  I so, sin(x) = x for small angles, and sin(0)=0.
So, you won't see anything in the first few samples anyway.


> From your explanation, I should be ok with even a low number of
> samples. When I tested my setup, I couldn't catch anything on the
> scope. There is probably some problem in how I made the app.
> 
> I saw something mentioned elsewhere in the discussion archives that
> the usrp dumps the first few samples it receives from the host before
> transmitting. Is this still something to take note of?

I don't know whether or not the USRP dumps the first few samples.  I
don't think I've ever experienced it though.  I can say that there is an
unpredictable delay from the generation of the first sample in software
until the time it actually reaches the output port.  

I haven't tried to do what you're doing -- i.e., capture the first few
output samples on a scope.  How is the scope triggered?  (What I did was
create a loopback whereby I transmit and receive by reading the
bleedover on the daugherboard.)

-Lee