Metrology geeks will make every effort to ensure that their measurements are the best, their instruments are the most accurate, and their calibration is on-site. There was a time when it would be a difficult task for time and frequency geeks, but with the emergence of GPS satellites with ultra accurate atomic clocks overhead, it became extremely easy to accurately master frequencies. [land floor] has a GPS 10 MHz clock, which is based on a set of modules.
Since many GPs modules have 10 MHz output, people may think that this module simply connects the socket to the module and has been completed, but it uses their other project, a fast side pulse generator, which uses the GPS output as its oscillator, buffer and signal conditioner. Add a QT py microcontroller board to set up GPS, and you have an independent 10 MHz source that can compete with any standard. Full details can be found on the project wiki, and the firmware can be found on GitHub.
Be careful of your exploration of standard frequencies, as this may lead to rabbit holes.