How to achieve change values of parameters at runtime

GNU Radio
1

hi all,
could anyone please let me know how to change the value of a parameter
already initialized to a different value at runtime?

I guess usage of lock() and unlock() will work. But not sure how to go
about this?

2

Thanks Eric… I will be more specific about the problem… here it
is…

I am trying to combine the spectrum sense and ODFM Tx code together
using multi flow graph concept. I idea is to sense the spectrum for
occupancy and if free, use that frequency for OFDM transmission. So
far I have achieved the connection between spectrum sense flow graph
and the OFDM Tx flow graph. I am taking both the spectrum sense
parameters and OFDM Tx parameters together at the time of
initialization.
The code is working fine performing the spectrum sense and ofdm
transmission. But the frequency at which the OFDM transmission is
happening is not at the frequency sensed to be free. Instead it is
happening at the initialized frequency (–tx-freq parameter). I want
this parameter to be changed at runtime. I have given following piece
of code for the same:

class my_top_block(gr.top_block)

tx = my_top_block()

3

On Thu, Jun 11, 2009 at 01:44:24PM +0530, Sheshanandan KN wrote:

hi all,
could anyone please let me know how to change the value of a parameter
already initialized to a different value at runtime?

I guess usage of lock() and unlock() will work. But not sure how to go
about this?

You’re not being very specific, which makes it hard for anybody to be
of assistance to you.

Please see http://gnuradio.org/trac/wiki/ReportingErrors and try again.

Eric

4

Sheshanandan KN wrote:

parameters and OFDM Tx parameters together at the time of
self.sp_sense = spectrum_sense()
if power < threshold:
print ‘spectrum is free’
tx.ofdm_tx._tx_freq = m.center_freq

Then I perform ofdm transmission. But the last statement here has no
effect in the execution. Please let me know what is the mistake with
this kind of change of parameter value. I am looking to have this kind
of runtime change in value of parameter.

tx.ofdm_tx._tx_freq is just a variable holding the frequency, but does
not set it.

You have to re-tune the usrp (tb.set_freq(new_freq)).

Tom

5

Hi all,
Please ignore the previous mail. It is not complete. It was sent
accidently.

Thanks Eric… I will be more specific about the problem… here it
is…

I am trying to combine the spectrum sense and ODFM Tx code together
using multi flow graph concept. I idea is to sense the spectrum for
occupancy and if free, use that frequency for OFDM transmission. So
far I have achieved the connection between spectrum sense flow graph
and the OFDM Tx flow graph. I am taking both the spectrum sense
parameters and OFDM Tx parameters together at the time of
initialization.
The code is working fine performing the spectrum sense and ofdm
transmission. But the frequency at which the OFDM transmission is
happening is not at the frequency sensed to be free. Instead it is
happening at the initialized frequency (–tx-freq parameter). I want
this parameter to be changed at runtime. I have given following piece
of code for the same:

class my_top_block(gr.top_block)

   self.sp_sense = spectrum_sense()
   self.ofdm_tx = ofdm_transmit()

   self.connect(ofdm_tx)
   self.connect(sp_sense)

tx = my_top_block()

Now, in the main program, I do something like this:

if power < threshold:
print ‘spectrum is free’
tx.ofdm_tx._tx_freq = m.center_freq

Then I perform ofdm transmission. But the last statement here has no
effect in the execution. Please let me know what is the mistake with
this kind of change of parameter value. I am looking to have this kind
of runtime change in value of parameter.

Shesh

On Sun, Jun 14, 2009 at 12:19 PM, Sheshanandan