On Tue, May 26, 2009 at 8:08 PM, Ujala Qasim <ujala.qa...@gmail.com> wrote:
> I captured the samples using the following C++ interface which is already
> available for USRP:
> // Simple C++ USRP interfacing demonstration program
> //
> //
> // This program was derived and modified from test_usrp_standard_rx.cc
> /* -*- c++ -*- */
> /*
> * Copyright 2003,2006,2007,2008 Free Software Foundation, Inc.
> *
> * This file is part of GNU Radio
> *
> Page 53 of 90
> * GNU Radio is free software; you can redistribute it and/or modify
> * it under the terms of the GNU General Public License as published by
> * the Free Software Foundation; either version 3, or (at your option)
> * any later version.
> *
> * GNU Radio is distributed in the hope that it will be useful,
> * but WITHOUT ANY WARRANTY; without even the implied warranty of
> * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> * GNU General Public License for more details.
> *
> * You should have received a copy of the GNU General Public License
> * along with GNU Radio; see the file COPYING. If not, write to
> * the Free Software Foundation, Inc., 51 Franklin Street,
> * Boston, MA 02110-1301, USA.
> */
> #include "usrp_standard.h"
>
> // Dumy Function to process USRP data
> void process_data(int *buffer)
> {
> }
> #define SAMPELS_PER_READ (512) // Must be a multiple of 128
> int main (int argc, char **argv)
> {
> bool loopback_p = false;
> bool counting_p = false;
> bool width_8_p = false;
> int which_board = 0;
> int decim = 8; // 32 MB/sec
> double center_freq = 0;
> int fusb_block_size = 0;
> int fusb_nblocks = 0;
> int nchannels = 1;
> int gain = 0;
> int mode = 0;
> int noverruns = 0;
> bool overrun;
> int total_reads = 10000;
> int i;
> int buf[SAMPELS_PER_READ];
> int bufsize = SAMPELS_PER_READ*4;
>
> if (loopback_p) mode |= usrp_standard_rx::FPGA_MODE_LOOPBACK;
>
> if (counting_p) mode |= usrp_standard_rx::FPGA_MODE_COUNTING;
>
> usrp_standard_rx_sptr urx = usrp_standard_rx::make (which_board, decim, 1,
> -1, mode, fusb_block_size, fusb_nblocks);
>
> if (urx.px == 0)
> {
> fprintf (stderr, "Error: usrp_standard_rx::make\n");
> exit (1);
> }
>
> if (width_8_p)
> {
> int width = 8;
> int shift = 8;
> bool want_q = true;
> if (!urx->set_format(usrp_standard_rx::make_format(width, shift, want_q)))
> {
> fprintf (stderr, "Error: urx->set_format\n");
> exit (1);
> }
> }
> // Set DDC center frequency
> urx->set_rx_freq (0, center_freq);
> // Set Number of channels
> urx->set_nchannels(1);
> // Set ADC PGA gain
> urx->set_pga(0,gain);
> // Set FPGA Mux
> urx->set_mux(0x32103210); // Board A only
> // Set DDC decimation rate
> urx->set_decim_rate(decim);
> // Set DDC phase
> urx->set_ddc_phase(0,0);
>
> urx->start(); // Start data transfer
>
> printf("USRP Transfer Started\n");
> // Do USRP Samples Reading
> for (i = 0; i < total_reads; i++)
> {
> urx->read(&buf, bufsize, &overrun);
> if (overrun)
> {
> printf ("USRP Rx Overrun\n");
> noverruns++;
> }
> // Do whatever you want with the data
> process_data(&buf[0]);
> }
>
> urx->stop(); // Stop data transfer
> printf("USRP Transfer Stoped\n");
>
> //delete urx;
> return 0;
> }
>
>
> On Tue, May 26, 2009 at 8:04 PM, Jason Uher <jasonu...@gmail.com> wrote:
>
>> On Tue, May 26, 2009 at 1:24 AM, Ujala Qasim <ujala.qa...@gmail.com>
>> wrote:
>> > I set my decimation rate to 200 and center_freq to 100.1, but the values
>> of
>> > my samples is exceeding this range.
>>
>> > Please specify the mistake that I'd be making...
>>
>> This is very hard to do without any information at all regarding how
>> you captured the samples.
>>
>> My first guess would be that you are doing on of the following:
>>
>> Your flowgraph is modifying the values out of the usrp
>>
>> - or - (more likely)
>>
>> Whatever tool you are using to read in the samples is not doing so
>> correctly.
>>
>> If you are using Linux I would install Octave and use the scripts in
>> "{trunk}/gnuradio/gnuradio-core/src/utils" to read the saved data from
>> a file_sink into Octave and check if you are still getting the same
>> kind of data.
>>
>> Jason
>>
>
>
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