Re: [Discuss-gnuradio] block for continuous production of samples

[Martin Braun]

On Thu, Feb 25, 2010 at 04:16:20PM +0100, Daniele Bertussi wrote:
> Good morning,
> I need to implement a double 802.15.4-802.11b transmitter that transmits 
> packets in asynchronous (or aperiodical) mode.
> I realized a simple program where the output of the two trasmitters are added 
> together to generate the output stream.
> Unfortunately,  when one of the two transmitters ends to generate a packet, 
> also the other one stops. It happens ( i think! ) because there are no 
> samples for the adder to combine with and the forecast() method stops the 
> execution.
> By the way, I found online a similar discussion:
> http://www.mail-archive.com/address@hidden/msg08387.html
> In order to have a countinuos output stream even when the two transmitters 
> are inactive, could I implement a gnuradio c++ block with the following 
> characteristics?
> -performs a continuous production of null samples (when there are no input to 
> the block)
> -lets the samples unchanged if there are samples at his input.

I wrote some code a while ago that attempted exactly that (I'll email you the
stuff off-list), but you need to be careful that it does exactly what
you want. At the very least, put in a throttle or you'll end up creating
billions of zeros before the scheduler comes round to insert your
signal.

MB

-- 
Karlsruhe Institute of Technology (KIT)
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