page_title: Quartz clock
section_title: Internal adjustment
hierarchical_section_title: Quartz clock / Accuracy / Internal adjustment
caption_attribution_description: English: Omega Constellation Megaquartz F4.19mhz ships clock, French Navy issued. The calibre 1525 movement uses an advanced 4.19 MHz quartz resonator operated at 223 or 4,194,304 Hz frequency giving an accuracy of less than ± 5 seconds per year. The clock was designed at the request of the French Navy. This ships clock was available commercially at great expense but was predominantly used for military application with the French Navy, who used the Marine Chronometer clock in the majority of their fleet. The clock was supplied in a mahogany box with brass fitting and was very much a case of function over form and built to the highest of military specifications including anti magnetic shielding. The clocks were all individually numbered on a brass plaque and ran on 2 AA type batteries, three of which ran the clock and a fourth was used as a back up power source when changing the other batteries and standard running time for a set of batteries was circa 3 years.
context_page_description: A quartz clock is a clock that uses an electronic oscillator that is regulated by a quartz crystal to keep time. This crystal oscillator creates a signal with very precise frequency, so that quartz clocks are at least an order of magnitude more accurate than mechanical clocks. Generally, some form of digital logic counts the cycles of this signal and provides a numeric time display, usually in units of hours, minutes, and seconds.
  The world's first quartz clock was built in 1927 by Warren Marrison and J. W. Horton at Bell Telephone Laboratories. The world's first quartz watch, however, was unveiled by Japanese watchmaker Seiko as the Astron in December 1969. Since the 1980s, when the advent of solid-state digital electronics allowed them to be made compact and inexpensive, quartz timekeepers have become the world's most widely used timekeeping technology, used in most clocks and watches as well as computers and other appliances that keep time.
context_section_description: Some premium movement designs self-rate and self-regulate. That is, rather than just counting vibrations, their computer program takes the simple count and scales it using a ratio calculated between an epoch set at the factory, and the most recent time the clock was set. These clocks become more accurate as they age.
  It is possible for a computerized high-accuracy quartz movement to measure its temperature and adjust for that as well.  Both analog and digital temperature compensation have been used in high-end quartz watches. In more expensive high-end quartz watches, thermal compensation can be implemented by varying the number of cycles to inhibit depending on the output from a temperature sensor. The COSC average daily rate standard for officially certified COSC quartz chronometers is ±25.55 seconds per year at 23 °C. To acquire the COSC chronometer label, a quartz instrument must benefit from thermo-compensation and rigorous encapsulation. Each quartz chronometer is tested for 13 days, in one position, at 3 different temperatures and 4 different relative humidity levels. Thermocompensated quartz movements, even in wrist watches, can be accurate to within ±5 to ±25 seconds per year and can be used as marine chronometers to determine longitude by means of celestial navigation.
caption: Omega 4.19 MHz Ships Marine Chronometer, French Navy issued
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