Thanks Tim Good reads and not even behind a paywall. Pretty neat details and thank heavens a raspberrypie is in the mix... Regards Paul WB8TSL
On Fri, Jul 7, 2017 at 5:59 PM, jimlux <[email protected]> wrote: > On 7/7/17 1:51 PM, Tim Lister wrote: > >> Three recent papers from the APOLLO project showed up on my VoxCharta >> summary of arxiv.org which may be of interest to the time-nuts >> community. They are to do with improving the precision and absolute >> calibration of the lunar laser ranging project based at the 3.5m WIYN >> telescope at Apache Point. >> >> The links are: >> http://arxiv.org/abs/1707.00204v1 (Timing calibration of the APOLLO >> experiment) >> http://arxiv.org/abs/1706.09550v1 (An absolute calibration system for >> millimeter-accuracy APOLLO measurements) >> http://arxiv.org/abs/1706.09421v1 (APOLLO clock performance and normal >> point corrections) >> >> I was surprised by a few things: 1) that the size of GR effects on the >> Moon's position was at the 10 meter level (or ~0.01% >> measurable/testable level for the millimeter-level precision reached >> by APOLLO) and 2) the relatively coarse frequency steps the XL-DC >> GPSDO previously used was capable of. Does anyone know what sort of >> oscillator these used ? I thought most (good) OCXOs had/have a EFC at >> the 1e-13 level but maybe "back in the day" the availability of >> suitable DACs with a large dynamic range was more of an issue ? >> >> Cheers, >> Tim >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/m >> ailman/listinfo/time-nuts >> and follow the instructions there. >> >> > The XL-DC had a wide array of options. I used to buy them with a low phase > noise 10 MHz OCXO, but there were other options. One of the papers > mentioned 50MHz coming from the XL-DC, so that must have been from a > different flavor of the unit. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/m > ailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ 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.
