Friday, April 1, 2016

Re: [Discuss-gnuradio] radio astronomy fast radio burst help requested

There are 3 options that I can think of:
1)  Use multiple SDRs at each location.
2)  Run an optimization algorithm as a post processing step to figure out what the phase synchronization should be. 
3)  If there is a transmitting satellite near there in frequency, use that to determine what the phase synch should be.

Each of these has a problem.
1) The necessary budget is larger.
2) This will be computationally expensive if the feature to search for is unknown.
3) The sat signal and the bursts being looked for may propagate through the ionosphere differently and so this may prove to be unreliable.

On Fri, Apr 1, 2016 at 9:59 AM, <mleech@ripnet.com> wrote:

VLBI guys usually have a local H1 maser clock, they go through a complex synchronization ritual prior to the start of observations.    H1 masers have short-term stability on the order of 1e-16.

GPS synchronization would be a *starting point* for such things.

 

 

On 2016-04-01 08:42, madengr wrote:

What would it take to get phase coherency, say at 1 GHz, on a global scale;  short of running cables?  I assume with a moderate priced GPSDO one can get  10E-12 stability, so that would be 0.01 Hz frequency stability at 1 GHz.   Does that mean you can integrate for 10 seconds and stay within 0.1 radian  phase drift?  Lou        Marcus D. Leech wrote
Since those stations would likely not be phase-coherent, then any spectra adding would only improve sensitivity by sqrt(N)--you don't get to effectively use the sum of the effective apertures of the individual stations.
      --  View this message in context: http://gnuradio.4.n7.nabble.com/radio-astronomy-fast-radio-burst-help-requested-tp59287p59297.html  Sent from the GnuRadio mailing list archive at Nabble.com.    _______________________________________________  Discuss-gnuradio mailing list  Discuss-gnuradio@gnu.org  https://lists.gnu.org/mailman/listinfo/discuss-gnuradio  

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