Re: [Discuss-gnuradio] Frequency error in USRP.
On 4/10/07, Brian Padalino <[EMAIL PROTECTED]> wrote: What type of modulation are you using and what is your application? GMSK modulation for Relay channels. Currently I am trying to relay the voice on two hop system. Brian Tarun ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Frequency error in USRP.
On 4/10/07, Tarun Tiwari <[EMAIL PROTECTED]> wrote: Can you please enlighten me, how to deal with this problem, as this is pretty obvious in a practical system. What type of modulation are you using and what is your application? Brian ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Frequency error in USRP.
Hi Brian, Thank you for reply. On 4/10/07, Brian Padalino <[EMAIL PROTECTED]> wrote: The 64MHz oscillator on the board has a maximum 50PPM error. This gives an error of up to 3200Hz. To get to 2.4GHz, that's 37.5x the 64MHz local oscillator. 3200Hz * 37.5 = 120kHz. 2.4e9 - 120e3 = 2.399880e9 So, in my case its OK and in the range right... i.e. 2.4 GHz - 2.39989 GHz = 110 kHz So it is pretty possible that your oscillators are just that far off? Can you please enlighten me, how to deal with this problem, as this is pretty obvious in a practical system. Brian Tarun ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Frequency error in USRP.
Hi Chris, Thank you for your reply. On 4/10/07, Chris Stankevitz <[EMAIL PROTECTED]> wrote: In my application (GPS), I don't even know the desired frequency due to the doppler effect on the fast moving satellites. I use an acquisition routine to locate the frequency which uses FFTs in my custom block. Your acquisition routine need any pilot for clock recovery or what? Are you using FFT to look for highest signal power? And, if your code is under GPL, can you please help me out with providing that to me and this group? Chris Tarun ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Frequency error in USRP.
On 4/10/07, Tarun Tiwari <[EMAIL PROTECTED]> wrote: Hi Matt, Eric, and my dear friends, I received third set of USRP for my research work, but the third USRP is not able to lock/demodulate the desired frequency. When i transmit a signal on 2.4GHz from one of the old USRPs I need to lock the new USRP at 2.39989 GHz else it does not demodulate the signal. The 64MHz oscillator on the board has a maximum 50PPM error. This gives an error of up to 3200Hz. To get to 2.4GHz, that's 37.5x the 64MHz local oscillator. 3200Hz * 37.5 = 120kHz. 2.4e9 - 120e3 = 2.399880e9 So it is pretty possible that your oscillators are just that far off? Brian ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Frequency error in USRP.
Tarun Tiwari wrote: the local oscillators may not be perfect They definitely will note be perfect. But, the question is how do I recover the signal if my receiver clock does not synchronize to the desired frequency? In my application (GPS), I don't even know the desired frequency due to the doppler effect on the fast moving satellites. I use an acquisition routine to locate the frequency which uses FFTs in my custom block. Chris ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Frequency error in USRP.
Hi Matt, Eric, and my dear friends, I received third set of USRP for my research work, but the third USRP is not able to lock/demodulate the desired frequency. When i transmit a signal on 2.4GHz from one of the old USRPs I need to lock the new USRP at 2.39989 GHz else it does not demodulate the signal. Although the verbose mode displays that there is no frequency error in the system, but if I am not able to demodulate on 2.4GHz then where's the problem. I do understand that the local oscillators may not be perfect, because two devices can not have same precision all the time. But, the question is how do I recover the signal if my receiver clock does not synchronize to the desired frequency? If you can illuminate something on it, it would be great help. Thanks in advance. Tarun University of Texas-Dallas ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio