Hello All,
I'm trying for discontinuous transmission of random packets to
exhibit *two state markov model(ON and OFF cycles).*The states for markov
model are generated by predefined transition matrix. I utilized the *
benchmark_tx.py* *example* in digital section ,which has discontinuous
transmission for every 5 packets.
Currently, I made little modifications to the code so that for ON state
random packets are transmitted and for the OFF state, time.sleep function is
performed. The program runs fine for* small burst of packets (1,2 or 4
packets for ON cycle)* but, if I transmit *big burst of packets(10,15 or 20
packets for ON cycle)* then OFF cycle is completely dead which causes in
continuous transmission.
Questions:
1. * I assume the flow-graph is still active even during the OFF
cycle(data is still processing through the GNU blocks)??*
* 2. Is time.sleep() function is an appropriate way to use for OFF
cycles in my model ?? If not can anyone suggest me better way to break the
transmission using GNU blocks ??*
* 3. Is there anyway to control the transmission at python level by
using single or multiple flowgraph model or suggestion to implement any new
block ??? *
* Multiple flowgraph Approach* :
* I tried to provide a two flowgraph model for ON and OFF cycles;I
switch between the two depending on the markov state. *
*
*
*ON cycle flow -graph:*
* packet modulator --------> modulator ----------> ampl -----------> usrp
sink*
*
*
*OFF cycle flow-graph *
* packet modulator --------> modulator ----------> ampl ----------->null
sink*
* *
4. Does my problem has anything to do with in band timestamp of
packets ???
It would be great if someone guide if I'm wrong in understanding GNU Radio
architecture.Thanks in advance.
*Model : USRP 1 + RFX 2400 *
*OS : Ubuntu 9.0.4*
Regards
Venkat Vinod Patcha
Research Assistant
Electrical Engineering
Louisiana State University
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