Transmitter code

GNU Radio
1

Dear Eric,

I am searching for a code that allows both the antennas of USRP transmit
simultaneously.

I want to use both the daughter boards of a USRP board as transmitter.

Regards,
Harshal

2

On Wed, Sep 09, 2009 at 08:10:03PM -0700, harshal jadhav wrote:

Dear Eric,

I am searching for a code that allows both the antennas of USRP transmit
simultaneously.

I want to use both the daughter boards of a USRP board as transmitter.

Regards,
Harshal

Please have a look at

gnuradio-examples/python/usrp/fm_tx_2_daugherboards.py

Eric

3

thanx Eric

4

Hi Eric,

I have a few questions regarding MIMO + GNU RADIO.

  1. How can i use MIMO with GRC?

If i use one USRP sink, it considers one whole USRP board. I cannot use
two
daughter boards of the same USRP board using USRP sink.

  1. In gnuradio-examples/python/usrp/fm_tx_2_daughterboards.py can i use
    flex 900 boards?

I have tried implementing the example with the flex 900 board but it
shows
more of noise. I changed the sinusoid signal frequency to 4000 Hz and
10000
Hz. While running the code it asks for carrier frequency for both the
signals. I have given the frequency to 900 MHz.

REGARDS,
HARSHAL JADHAV

5

On Mon, Sep 14, 2009 at 08:01:17PM -0700, harshal jadhav wrote:

Hi Eric,

I have a few questions regarding MIMO + GNU RADIO.

  1. How can i use MIMO with GRC?

If i use one USRP sink, it considers one whole USRP board. I cannot use two
daughter boards of the same USRP board using USRP sink.

Josh is the right person to handle this part, though it’s just a
matter of setting up the transmit mux and interleaving the samples.

  1. In gnuradio-examples/python/usrp/fm_tx_2_daughterboards.py can i use
    flex 900 boards?

Yes.

I have tried implementing the example with the flex 900 board but it shows
more of noise. I changed the sinusoid signal frequency to 4000 Hz and 10000
Hz. While running the code it asks for carrier frequency for both the
signals. I have given the frequency to 900 MHz.

Your baseband frequency needs to be representable without aliasing
given the baseband sample rate. With interp=400, the baseband rate is
128e6/400 = 320kS/s, so you should be able to represent anything from
about -150kHz to +150kHz.

For your MIMO usage, set both the side-A-tx-freq and side-B-tx-freq to
the same value, say 906e6.

The example multiplies the signals by 10000. Try using a smaller
value for if_gain, say 4000.

Eric

6

Thanks a lot Eric…Your suggestion worked perfectly fine…the result
is
even more clear if u increase the distance between the transmitting
antenna…

at the receiver end i was using GRC. So i had to connect only one
antenna. I
havent found an option in GRC, wherein i can use two USRP sink for the
same
USRP board. For two USRP sink i have to use two boards… Have to find a
way
of using the daughterboards of the same USRP board to receive the
signal,
thus making the system purely MIMO. The system that has worked for me is
MISO.

Regards,
Harshal