[HN Gopher] HP 5061A Cesium Clock [video] ___________________________________________________________________ HP 5061A Cesium Clock [video] Author : brudgers Score : 28 points Date : 2020-03-25 05:02 UTC (17 hours ago) (HTM) web link (www.youtube.com) (TXT) w3m dump (www.youtube.com) | MUHAMMADRIZWAN wrote: | https://thekrjaan.com/tiktok-videos-how-to-download-tiktok-v... | fsh wrote: | Amazing piece of technology. Its successor, the 5071A (now made | by microsemi) is still the most common primary frequency | standard. HP used to be such a great company. Now they make | crappy consumer printers and network cables with DRM chips. | jimmySixDOF wrote: | These things used to be critical elements in optical | transmission for circuit switched telephone networks | (SONNET/SDH). The old "5 9's" Reliability commitment ment your | Stratum clock was working across the whole ring. Now you just | throw a GPS antenna on every base station ! | willis936 wrote: | You still need low phase noise local oscillators. Both atomic | standards and GPSDOs use ovenized crystal oscillators (double | ovenized if they're fancy). | | It blows my mind that at the end of the day, the lowest noise | method of single frequency electrical signal generation we | have is a mechanical system. | Gibbon1 wrote: | HP spun off the good parts in 1999 to form Agilent. The Test | Equipment division was spun off in 2014 as Keysight | | https://en.wikipedia.org/wiki/Agilent_Technologies | https://en.wikipedia.org/wiki/Keysight | abjecton wrote: | I find this video quite interesting. | | I had no idea how Cesium clocks work, other than the SI | definition of a second is 9xxxx transitions between two states of | a cesium atom. | fsh wrote: | "Transition frequency" seems to be a common source of confusion | here. In the context of the SI definition it means "frequency | corresponding to the energy difference between the two states". | This is the frequency of radiation that can _most efficiently_ | drive transitions between the states. How fast the atom | transitions between the states depends on the frequency, | polarization, and power of the driving radiation and can in | principle take any value. To avoid confusion this is called the | "Rabi frequency" in atomic physics. ___________________________________________________________________ (page generated 2020-03-25 23:00 UTC)