Accuracy Quartz clock

1 accuracy

1.1 inhibition compensation
1.2 internal adjustment
1.3 external adjustment

accuracy

the relative stability of quartz resonator , driving circuit better absolute accuracy. standard-quality resonators of type warranted have long-term accuracy of 6 parts per million (0.0006%) @ 31 °c (87.8 °f): is, typical quartz clock or wristwatch gain or lose 15 seconds per 30 days (within normal temperature range of 5 °c/41 °f 35 °c/95 °f) or less half second clock drift per day when worn near body.

inhibition compensation

many inexpensive quartz clocks , watches use technique known inhibition compensation. crystal deliberately made run fast. after manufacturing, each module calibrated against precision clock @ factory , adjusted keep accurate time programming digital logic skip small number of crystal cycles @ regular intervals such 10 seconds or 1 minute. typical quartz movement allows programmed adjustments in 7.91 seconds per 30 days increments 10 second intervals (on 10-second measurement gate) or programmed adjustments in 1.32 seconds per 30 days increments 60 seconds intervals (on 60-second measurement gate). advantage of method using digital programming store number of pulses suppress in non-volatile memory register on chip less expensive older technique of trimming quartz tuning fork frequency. inhibition compensation logic of quartz movements can regulated service centers of precision timer , adjustment terminal after leaving factory, though many inexpensive quartz watch movements not offer functionality.

internal adjustment

some premium movement designs self-rate , self-regulate. is, rather counting vibrations, computer program takes simple count, , scales using ratio calculated between epoch set @ factory, , recent time clock set. these clocks become more accurate age.

it possible computerized high accuracy quartz movement measure temperature, , adjust well. both analog , digital temperature compensation have been used in high-end quartz watches. in more expensive high end quartz watches, thermal compensation can implemented varying number of cycles inhibit depending on output temperature sensor. cosc average daily rate standard officially certified cosc quartz chronometers ± 25.55 seconds per year. thermo compensated quartz movements, in wrist watches, can accurate within ± 5 ± 25 seconds per year , can used marine chronometers determine longitude means of celestial navigation.

external adjustment

if quartz movement rated measuring timekeeping characteristics against radio clock s time broadcast, determine how time watch gains or loses per day, , adjustments made circuitry regulate timekeeping, corrected time accurate within ± 10 seconds per year. more adequate perform celestial navigation.