Re: [Discuss-gnuradio] Using one USRP
Hi Ali, I have done the similar as a part in my thesis as well. But I used two USRPs to serve as receiver and transmitter. When u try to listen on a daughter board using same USRP and transmit simultaneously ( which I tried ) you do not receive the transmitted signal. I did not dwell much on this because I had two USRPs to serve as two users. I know that both tramsitter and receiver programs can be run using two daughter boards. *But the receiver in this case seems to receive only signals send from other USRPs. But signals Transmitted from a diiferent antenna/daughter board on same USRP was not received*. I used this isolation for my benefit to run a scanner simultaneously to detect signal from while transmission is going on. I do not know if this isolation can be removed by changing some parameters. I do not have access to my boards now will try it next week and let you know.But I would recommend you to search the archive there are some related discussions. Thank you Swapna 2009/3/20 ali siddiqi chain...@gmail.com Hi I am trying to implement a cognitive radio system for dynamic spectrum access. I am trying to implement it in GNU radio. But the problem is that i have only one USRP at the moment with Basic RX and TX daughterboards. The setup consists of Station A transmitting to Station B. In order to be able to use the licensed spectrum, the transmitter must know which channels are free in the vicinity. Thus it has to do a parallel detection of spectrum as well---receiver mode. The Transmitter first senses the spectrum for some time say 10ms and then transmits on the free frequency for say 90 ms before sensing the spectrum again and so on. Thus the following questions arise: 1. Can the Station B be implemented on the same USRP when the Station A is only transmitting[not sensing(recieving)]? 2. What effects would this have on the Data Rates and any problem with the USB interface? Is there any built in example within gnuradio with which i can test the simultaneous transmission and reception from the BasicTX to the BasicRX respectively on the same usrp? Regards, Ali ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Measuring SNR
Hi, I am trying to implement a particular channel coding technique as part of my work(Master's Thesis). I need to test this technique in a fading channel. But since I have no control over the channel I cannot quantify channel condition.I need SNR to analyze the performance of the coding technique.The only solution i thought was to inject noise at source and ensure that transmission.But this is more like a simulation. I would like to know if there are better ways to do this. My second question is more related to Python programming. I need to run a series of scripts one after the other in my work.Though these scripts work fine independently. I get an error when I use os.popen(). In most cases I do not want the control to return back to the calling script.Could any one suggest what is the best way to do this, or atleast a reference? Thanks Swapna ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Measuring SNR
Eric, Thank You. os.system() worked. I can now switch between different scripts while in transmitting mode. To all, While receiving data (using a modification of benchmark_rx.py) I need to receive at a different frequency depending on some control information . I get an error message while attempting to do this using os.system().It says * cannot connect to usb interface, cannot connect to usrp1*. I tried the following and it doesn't work 1.I tried using flowgraph.disconnect and flowgraph.close() before calling the second script. 2.I tried calling os.system() after exiting rx_callback and main() but it still can't connect to the source. 3.I also tried changing frequency instead of calling a separate script inside rx_callback() How can I ensure that the receive path is completely disconnected and usrp_source is available? thanks , Swapna ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Measuring SNR
I am sorry if my previous mail was confusing. I am trying to switch toa different Rx freq depending on a control information. Even though I exit from rx_callback and try to call a new script for Rx using os.system I get an error message saying USB _claim_interface :failed interface 2 Device or resource busy can't open rx_interface can't open usrp1. I closed /disconnected the flowgraph before attempting to open a new script. How can I ensure that the rx_path is clear? Thank you Swapna On Thu, Feb 12, 2009 at 9:19 PM, Swapna Raj swapna.ra...@gmail.com wrote: Eric, Thank You. os.system() worked. I can now switch between different scripts while in transmitting mode. To all, While receiving data (using a modification of benchmark_rx.py) I need to receive at a different frequency depending on some control information . I get an error message while attempting to do this using os.system().It says * cannot connect to usb interface, cannot connect to usrp1*. I tried the following and it doesn't work 1.I tried using flowgraph.disconnect and flowgraph.close() before calling the second script. 2.I tried calling os.system() after exiting rx_callback and main() but it still can't connect to the source. 3.I also tried changing frequency instead of calling a separate script inside rx_callback() How can I ensure that the receive path is completely disconnected and usrp_source is available? thanks , Swapna ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] benchmark_rx.py
Hello all, i'm trying to send and receive data using benchmark_tx.py and benchmark_rx.py When i run benchmark_rx.py the rx_callback is not being executed. None og the print statements in the rx_callback is getting being printed. I get the warning failed to enable realtime scheduling. I'm already running both tx and rx in verbose(-v) . ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] M Blocks Help
Hello all, where can I find documentation on mblocks. how can i get some example codes to learn to exploit a few features of mblocks. I'm trying to send control messages between USRPs carrying some desired information like frequency. Where can i learn about features of M blocks and tested examples.. Thank you SR ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] ADSL Modem
Hello, Has anyone ever implemented ADSL using GNU Radio. It should be possible rite? I would like to know about the hardware requirements. Could someone kindly enlighten me about the hardware requirements. Thank You Swapna ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Data from FFT sink
Hi all, I'm using RFX2400 in my research to build a cognitive radio based system. i'm performing a Spectrum scan and displaying the spectrum using fftsink2.But i need to display as well as get the data for further analysis. I went through the fftsink2 code but it did not help. I wanted to know if there is anyway to obtain the values after FFT is performed so as to compare with a threshold or communicate it to a peer. Thank You Swapna Raj ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Help for a beginner
Hi all, I'm new to GNU radio Software and USRP. We have recently purchased a USRP Board with RFX900 and RFX2400 Daughter Boards for our Lab. I work in a Telecommunications in PVAMU. I've a decent expertise in C++ and object oriented Programming. I tried figuring out how the whole system works by going through various example source codes. But I'm yet to get a feel of exactly what happens from the point a signal is received by the antenna till the final signal processing block. Can anyone send me a source code of an example using the above mentioned daughter boards.(RFX900 and RFX2400) I shall appreciate any other suggestion that will enhance my knowledge about how GNU radio works , how it interfaces with the USRP and the flow of control between various block. Thank You Swapna ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
