Thanks for the reply. I tested the parameter tx_amplitude=0.001 and I can get little transmit power I wanted. I can observe the bandwidth from the spectrum analyser. I also changed the bitrate and modulation to get different bandwidth. But I still have some questions about the difference of the transmit bandwidth and the filter bandwidth.
Marcus D. Leech wrote: > > On 06/30/2010 08:05 PM, Eric Blossom wrote: >> 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? >>> > All else being equal that should produce a 10dB change in signal power, > unless *something* in the > chain is already at saturation due to other factors in the Tx chain. > Keep in mind that a 10dB change > on a logarithmic scale isn't very much. > >>> 2、How do I know bandwidth of transmission and reception channels in >>> tunnel.py? >>> > There seem to be *two* versions of tunnel.py in the examples--which one > are you talking about? > Have you put the output of the transmit side on a spectrum analyser? > That would tell you > unambiguously what the bandwidth is, but also careful and > knowledgeable inspection of the > code will tell you what the theoretical bandwidth is. > > > > -- > Marcus Leech > Principal Investigator > Shirleys Bay Radio Astronomy Consortium > http://www.sbrac.org > > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > -- View this message in context: http://old.nabble.com/Power%EF%BC%8CBandwidth-and-spectrum-switch-problems-tp29031239p29045723.html Sent from the GnuRadio mailing list archive at Nabble.com. _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
