RF synchronized system

Hello,

I am trying to develop an multi-channel RF synchronized system using
eight
N210s with WBX. I distributed 10MHz reference to four systems and other
four
are slaved using MIMO cable.

I have few questions:

  1. Though, channels are synchronized, still they have a fixed phase
    offset
    between them. Is there a way to correct this? may be in DDC?

  2. How can I obtain time-stamped samples in gnuradio-companion?

  3. How can I store multiple channels in a single file in GRC?

  4. I am not using 1PPS reference at this time. Is it also important in
    this
    case.

Thanks,

Khalid.

On 04/16/2011 03:46 PM, Khalid J. wrote:

Hello,

I am trying to develop an multi-channel RF synchronized system using
eight N210s with WBX. I distributed 10MHz reference to four systems
and other four are slaved using MIMO cable.

I have few questions:

  1. Though, channels are synchronized, still they have a fixed phase
    offset between them. Is there a way to correct this? may be in DDC?
    Since you’re dealing with 8 independent PLL synthesizers, there will be
    a random phase offset among
    all of them that will remain fixed during a given ‘session’. You
    could perhaps correct this in
    the FPGA, but not, I think, using any of the “standard” features of
    the existing FPGA code.
  1. How can I obtain time-stamped samples in gnuradio-companion?

I don’t think that’s currently possible from within GRC. But if you use
the C++ API you can
arrange for that.

  1. How can I store multiple channels in a single file in GRC?
    I’d use the streams-to-vector block within GRC.
  1. I am not using 1PPS reference at this time. Is it also important in
    this case.
    If you want time-stamp synchronization, you need 1PPS input to provide
    for a
    synchronized starting point for timestamps.


Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org

Thanks Marc for the reply.

I am not very familiar with the use of C++ API. Just wondering if there
is a good example to start with. All I want, is to take the time-stamped
samples from multiple usrps and dump them to file.

Thanks,

Khalid.

Marcus D. Leech wrote in post #993254:

On 04/16/2011 03:46 PM, Khalid J. wrote:

Hello,

I am trying to develop an multi-channel RF synchronized system using
eight N210s with WBX. I distributed 10MHz reference to four systems
and other four are slaved using MIMO cable.

I have few questions:

  1. Though, channels are synchronized, still they have a fixed phase
    offset between them. Is there a way to correct this? may be in DDC?
    Since you’re dealing with 8 independent PLL synthesizers, there will be
    a random phase offset among
    all of them that will remain fixed during a given ‘session’. You
    could perhaps correct this in
    the FPGA, but not, I think, using any of the “standard” features of
    the existing FPGA code.
  1. How can I obtain time-stamped samples in gnuradio-companion?

I don’t think that’s currently possible from within GRC. But if you use
the C++ API you can
arrange for that.

  1. How can I store multiple channels in a single file in GRC?
    I’d use the streams-to-vector block within GRC.
  1. I am not using 1PPS reference at this time. Is it also important in
    this case.
    If you want time-stamp synchronization, you need 1PPS input to provide
    for a
    synchronized starting point for timestamps.


Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org

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