Re: [Discuss-gnuradio] Using one USRP

[Swapna Raj]

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 <address@hidden>

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

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