They (likely) have hardware designed specifically for their task that is higher cost and quality.
On Fri, Apr 1, 2016 at 10:35 AM, <mle...@ripnet.com> wrote: > The main thing is that these bursts are *weak* (< 1Jy typically), and > *short duration*. Detecting a CW weak source with smaller antennae is > feasible, because you can use long integration times. You have no such > option here, unless you're talking about hundreds or thousands of dipoles, > all phase coherent. > > For example, to equal the collecting area of Parkes, you'd need (at > 500MHz): > > Parkes gain: 45dBi > > Dipole gain: 2.15dBi > > 45 - 2.15 = 42.85dB(antenna) > > Almost 20,000 simple half-wave dipole antenna required, and they'd all > need to be phase-coherent. > > If I've botched the math, please correct me. > > > > > On 2016-04-01 10:20, Alexander Levedahl wrote: > > 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, <mle...@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 >> listDiscuss-gnuradio@gnu.orghttps://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >>
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