Re: [Discuss-gnuradio] Power ，Bandwidth and spectrum switch problems

[Eric Blossom]

On Tue, Jun 29, 2010 at 11:23:36PM -0700, Johnson_lu wrote:
> 
> Hi guys，
> Could anybody can help me for these problems？
> 1、I varied Tx_amplitude from 0.1 to 1 and measured the output with a
> spectrum analyzer. But the changes are very little. The output is almost the
> same when Tx_amplitude is 0.1 and 1.  How can I reduce the transmit power to
> a very little value?
> 
> 2、How do I know bandwidth of transmission and reception channels in
> tunnel.py? 
> 
> 3、I am using an USRP2 with Gnu Radio and XCVR2450 as daughterboard. I want
> to switch frequency among different channels 2.4G~2.5G. However, I find that
> switch only can succeed about 20 times, then fails. 
> The python code is: 
>         self.tb.lock()             
>         ok = self.tb.txpath.set_freq(new_freq) 
>         if not ok: 
>             print "Failed to set Tx frequency" 
>             raise SystemExit 
>         ok = self.tb.rxpath.set_freq(new_freq) 
>         if not ok: 
>             print "Failed to set Rx frequency" 
>             raise SystemExit                     
>         self.tb.unlock() 

FWIW, there's no need to use lock/unlock to change the frequency.
You only need to use those when you are reconfiguring the topology of
the graph.

Try it without those and see if it works.

Eric