Re: [Discuss-gnuradio] Passing a message from one block to other

[John Andrews]

Thanks Tom, I will definitely take a look at it and keep you informed.

Thanks,

John

On Thu, Jan 13, 2011 at 5:12 PM, Tom Rondeau <address@hidden> wrote:

On Wed, Jan 12, 2011 at 2:43 PM, John Andrews <address@hidden> wrote:
> Hi,
> Suppose I have two gnuradio blocks called gr_ACQUISITION and gr_TRACKING
> where, gr_TRACKING is dependent upon some result derived from gr_ACQ block.
> Is it possible to pass certain messages to gr_TRACK in order to change its
> state while the flowgraph is running? One way to do is to have an output
> line in gr_ACQUISITION that carries this info to the block gr_TRACKING but
> this doesn't seem like an attractive option to me.
>
> Thanks,
> John.

We have recently introduced the concept of stream tags into GNU Radio
that might be what you want. They are not currently well-documented,
but you can find some information in my presentations from this years
SDR conference (specifically Tues and Weds):
http://gnuradio.org/redmine/wiki/gnuradio/SDR2010

You can also see a simple example in the code source (you'll have to
be on the next branch in git right now):
gnuradio-examples/python/tags

I will hopefully soon find time to write more examples and document it
better. But hopefully, the examples will be enough to show you how to
add a tag to an output stream from one block and receive it in another
block.

If you manage to get it working, I'd be very interested to hear about
your experiences. What you are looking to do sounds like it could be a
perfect case study for the use of the tags that others could well
benefit from.

Tom