Re: [Discuss-gnuradio] Irregular sampling of input stream

[David Knox]

Not much of a response to my initial question, so I'll try to be more
specific with my questions.

What is the best way to send a gated/non-continuous gnuradio signal stream
between signal processing blocks?  My main signal path is a 'standard'
digital radio demodulation process, where data travels through a cascaded
chain of processing blocks, being converted from samples to symbols and then
to bytes.  However, I want to supplement this path with an auxilliary on/off
gated stream of 'raw' USRP samples from the earliest block, which handles
samples, to one of the later ones in the chain, which handles bytes.  My
current approach is to create an extra output in the sample-processing C++
block and then hook it up (in Python) to the newly-created input of the
downstream C++ byte-processing block.  

* Q1: Are there any scheduling/synchronization/real-time issues in gnuradio
with stopping and starting a gnuradio stream (using feedback signalling
between blocks or otherwise) like this?  
  - In my application, I need to ensure that the series of 'raw' samples is
the complete continuous set of samples that occured before a particular bit
was detected in the main demodulation path.
* Q2: Should I avoid such signalling feedback and just throw away the
samples at the downstream bit-processing block (e.g. by selectively routing
to a sink or to a local data structure in the downstream processing block)
or is this too expensive for CPU processing time?  
* Q3: Are there existing routines for timestamping samples/symbols/bits
accurately enough so that they can be accurately cross-referenced with each
other?

Answers/ suggestions/ warnings/ advice/ approaches/
pointers_to_similar_examples would all be appreciated.  / David
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