On 09/28/2013 02:15 PM, Jim Lux wrote: > >>> >>> Don't forget the Doppler and relativistic effects of the earth moving >>> around the solar system barycenter. But that's not much different >>> than you do for GPS (e.g. knowing satellite orbits, etc.) >> Naturally. You also needs to compensate for their decay-rate as you try >> to span longer periods. >> >> You can use them for navigation and time, just like GPS. Even seen a >> presentation on that. >> > > The big hiccup is that you need a fairly good sized antenna to detect > the pulsars. They're "bright" in the sense of radio astronomy, but > remember that those folks think in terms of 1000 ft apertures at > Arecibo and huge arrays like the VLA or ATA. > > http://www.radio-astronomy.org/pdf/pulsars.pdf > http://www.k5so.com/Radio_astronomy_pulsars.html - an 8.6 meter dish > with a UHF feed. He's using a Rb, by the way > > http://www.moetronix.com/pulsar/index.htm They used a 26 meter > antenna. Scrolling down, it looks like they're getting a whopping 0.5 > dB SNR on the Crab Nebula pulsar. > > > So, pulsar nav seems a bit impractical for present day space vehicles. > NCC-1701 Enterprise might be big enough to carry a suitable phased array. On a space-craft it becomes easier to handle thermal noises thought.
Cheers, Magnus _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
