Hi,

I have a use case similar to the one mentioned in this series of posts: 
http://lists.gnu.org/archive/html/discuss-gnuradio/2013-04/msg00421.html

I am using B200-mini with gnuradio flowgraph containing tx and rx parts. 
Transmit part contains a udp source block connected to a physical layer 
block(that processes channel encoded bits) and that is connected to a uhd sink 
block. Receive part has similar structure with uhd source, phy block and Socket 
Pdu block.

The transmit part should send data continuously to B200-mini. So there should 
be signal broadcasted all the time.(Think of it like a base station broadcast 
signal) To achieve this, the upper layer of gnuradio flowgraph sends packets 
periodically to gnuradio.

The receive part has very low latency when i measure with a known signal( from 
a test instrument). 

When using both transmit and receive parts, I measure the time passed between 
the moment a packet enters the udp source block on transmit side and the moment 
the same packet sent out from the receive part of the flowgraph to upper layer. 
The time passed changes between 150 to 300 ms for each run of the flowgraph. 
These numbers are for GR_FIXED_BUFFER_SIZE decreased to 2048. With default 
value of 32k, the time passed is around 2-3 seconds.

I have three questions:

1) What to do to fix the latency so that it does not change each time the 
flowgraph is run?
2) Can I decrease latency below the measured values?
3) Can B200-mini send ack packets for send calls, when there is no sob/eob 
flags are used?

If anyone previously dealt with a similar use case can offer alternative 
methods, it would be great!

Thanks in advance,

Murat
                                          
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