Re: [Discuss-gnuradio] always a spike on the FFT at the center frequency

2010-12-07 Thread Matt Ettus
On 12/05/2010 11:22 PM, adib_sairi wrote: Matt Ettus wrote: This is due to truncation in the USRP. If you add 0.5 to the signal, it should go away. Matt Dear Matt, how and where does the truncation is done? is it in the FPGA (DDC) ? At the output of the DDC. Matt ___

Re: [Discuss-gnuradio] always a spike on the FFT at the center frequency

2010-12-05 Thread adib_sairi
Matt Ettus wrote: > > > This is due to truncation in the USRP. If you add 0.5 to the signal, it > should go away. > > Matt > > > Dear Matt, how and where does the truncation is done? is it in the FPGA (DDC) ? regards, Adib - Mohd Adib Sarijari Universiti Teknologi Malaysia www.fk

Re: [Discuss-gnuradio] always a spike on the FFT at the center frequency

2010-12-02 Thread Matt Ettus
On 12/01/2010 01:16 PM, William Cox wrote: Whenever I run the userp_fft.py script (USRP1, Ubuntu 10.04 and 10.10), there's almost always a large spike (10-20 db above the noise floor) at the center frequency. This is the same for all the daughter boards I've tried (WBX, LFRX, and BasicRX). Why is

Re: [Discuss-gnuradio] always a spike on the FFT at the center frequency

2010-12-01 Thread Nick Foster
On Wed, 2010-12-01 at 16:16 -0500, William Cox wrote: > Whenever I run the userp_fft.py script (USRP1, Ubuntu 10.04 and > 10.10), there's almost always a large spike (10-20 db above the noise > floor) at the center frequency. This is the same for all the daughter > boards I've tried (WBX, LFRX, and

[Discuss-gnuradio] always a spike on the FFT at the center frequency

2010-12-01 Thread William Cox
Whenever I run the userp_fft.py script (USRP1, Ubuntu 10.04 and 10.10), there's almost always a large spike (10-20 db above the noise floor) at the center frequency. This is the same for all the daughter boards I've tried (WBX, LFRX, and BasicRX). Why is this? What am I missing? Thanks. -William __