Standalone USRP2

GNU Radio
1

We want to make several standalone transmitters which transmit OFDM
signals synchronized with 1pps signal and external 10MHz closk using
USRP2.

We want to implement the transmitters using FPGA, while daughter board
parameters and interpolation rate are fixed.

We will transmit “frames” which consist of preamble and fixed many data
OFDM symbols.

We want to ask following questions about above.

  1. Where does the “making frame block” connect with?

  2. What block may be deleted for elmenating corresponding GNU radio
    block?

  3. How do we modify the FPGA and/or firmware for fixing parameters
    (interpolation rate, center frequency, etc.)

  4. We may have to eliminate receiving buffer cause of shortage of
    memory.
    How can we delete it?

  5. If exists, please send us the whole system block diagram.

Thanks.

2

On Fri, Feb 13, 2009 at 10:50:54AM +0100, Yongsang K. wrote:

  1. We may have to eliminate receiving buffer cause of shortage of
    memory.
    How can we delete it?

  2. If exists, please send us the whole system block diagram.

Your best bet is to take a look at the existing code. With regard to
firmware, take a look at txrx.c and everything that it calls. All of
the peripherals visible to the firmware are defined in memory_map.h.
You can find data sheets for most of the wishbone peripherals under
usrp2/fpga/opencores

The top-level of the verilog is in usrp2/fpga/top/u2_rev3.

If you’re not connecting to the ethernet at all, you may be able to
remove the entire buffer_pool abstraction. Ultimately you’ll want to
clock your samples into the Tx DSP pipeline.

Eric