SSDT question

GNU Radio
1

Hi,

This question isn’t necessarily about GNU Radio but about SDR in
general.

I am studying spectrum sensing algorithms and I was reading about
simultaneous sensing and data transmission or SSDT for out-band sensing.
It
means that a radio is capable of transmitting data in one channel and
sensing at another different channel.

However, using a USRP2, I can only select one center frequency at a
time.
Considering I am applying sensing to signals which have a bandwidth of
6MHz,
in order to transmit/receive data in one channel and sense other
(different)
channels at the same time I need crazy sampling rates that GNU Radio
can’t
support. A 25 MS/s isn’t enough to make a scan for all the ISM Band as I
wanted.

So there are several answers for my problem:

  1. SSDT implies additional hardware making a single USRP2 simply not
    enough
  2. There is a way to tune different channel frequencies at the same time
    without any need to increase the sampling rate or use more than one
    USRP2
  3. I don’t understand SSDT and its limitations
  4. None of the above

Any help, suggestion, feedback would be nice

Francisco

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2

On Fri, May 4, 2012 at 5:52 PM, frankist
[email protected]wrote:

However, using a USRP2, I can only select one center frequency at a time.
Considering I am applying sensing to signals which have a bandwidth of
6MHz,
in order to transmit/receive data in one channel and sense other
(different)
channels at the same time I need crazy sampling rates that GNU Radio can’t
support. A 25 MS/s isn’t enough to make a scan for all the ISM Band as I
wanted.

You can tune the RX to one frequency and the TX to a different
frequency.
This is supported with all motherboards and all daughterboards except
the
XCVR2450.

So there are several answers for my problem:

  1. SSDT implies additional hardware making a single USRP2 simply not enough
  2. There is a way to tune different channel frequencies at the same time
    without any need to increase the sampling rate or use more than one USRP2

Yes. Just tune your TX and RX frequencies separately.

Matt