Re: [Discuss-gnuradio] tags_demo problem

[Sam mite]

On 05/20/2013 11:41 PM, Sam mite wrote:
> Hi list,
>
> Today I was trying to run one of the examples that come with gr-uhd
> "tags_demo" to schedule my burst transmission . I have USRP N210.  RFX2400.
> linux; GNU C++ version 4.6.3; Boost_104601; UHD_003.005.000-26-gb65a3924
>
> I want burst duration and idle duration of  0.012 and 1 seconds
> respectively.  So, I tried following command
>
> ./tags_demo --burst 0.012 --idle 1
>
> I observed that LED "A" on USRP flashes for very short period of time, and
> that I think is right because of short burst duration 12ms indicating
> transmission, after 1 sec idle duration. Question I want to ask is even if
> I kill the flow graph using Ctrl+C, LED "A" keeps on flashing with same
> behavior for some time and then finally stops. Why is that so?

Most likely, many transmit bursts are queued up on the device. The
example code that produces timed bursts doesnt wait for particular user
control or feedback from rx packets, its just sending out samples w/
burst tags -- which there is some finite amount of buffering upstream to
hold.

Thanks for the reply, problem goes away if I set burst and idle duration to 1 second.
A question. If I want not to transmit the samples/bursts that are coming during  the idle duration, how can I do that? For example, transmit a  single burst at time t1 for burst duration and then wait for time t2. The samples that are coming during wait time should never be transmitted. After idle duration a new burst of upcoming samples should be transmitted and so on. How should I go about it? Any pointers on this?  

>
> Also, LED "E" which was static while flow graph was running, blinks
> intermittently when flow graph has been stopped. But I think thats normal.
>

Thats ok, its just the ref lock light on a partially powered down
synthesizer.

Cheers,
-josh

>
> Regards,
>
> Sam

--

Sam