Valve Problem

I am trying to control my flow graph using a valve block. I have “Probe
Avg Mag^2” and “Number Sink” blocks after the “valve”. I want to control
this valve with a “Variable Chooser” block. I put the ID od variable
chooser block in the “open” field of the valve so that if the variable
chooser value is changed to True it will change the value of “open” in
valve but when do this the flow graph seems to stop working (stucked)
and nothing happens looks like there is a lot of processing going on in
behind. If I put the same value in the valve directly that ocurs in
variable chhoser before i run the flow graph, the valve seems to work by
opening the connection and Number Sink shows no value but when i control
the value of the valve during the program execution the program seems to
stop. Do i need to throttle or something else? The same problem occurs
whether I use FFT sink or Number Sink or any other.

Umair N.
MSc Communication Engineering
Chalmers University ot Technology, Sweden.

When in the open state, the valve is internally 2 blocks. A null sink,
and a null source + head(0) The valve will “eat” all incoming samples
without back-pressure. If you have no throttling, the means 100% CPU
utilization. I would put a throttle before the valve block.