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  2. Amateur radio repeater - Wikipedia

    en.wikipedia.org/wiki/Amateur_radio_repeater

    This technique allows for a smaller and less complex repeater system. Repeating signals across widely separated frequency bands allows for simple filters to be used to allow one antenna to be used for both transmit and receive at the same time. This avoids the use of complex duplexers to achieve the required rejection for same band repeating.

  3. Repeater (horology) - Wikipedia

    en.wikipedia.org/wiki/Repeater_(horology)

    The repeating clock was invented by the English cleric and inventor, the Reverend Edward Barlow in 1676. [2]: 206 His innovation was the rack and snail striking mechanism, which could be made to repeat easily and became the standard mechanism used in both clock and watch repeaters ever since. The best kind of repeating clocks were expensive to ...

  4. Frequency - Wikipedia

    en.wikipedia.org/wiki/Frequency

    Frequency (symbol f), most often measured in hertz (symbol: Hz), is the number of occurrences of a repeating event per unit of time. [1] It is also occasionally referred to as temporal frequency for clarity and to distinguish it from spatial frequency.

  5. Pulse-per-second signal - Wikipedia

    en.wikipedia.org/wiki/Pulse-per-second_signal

    A pulse per second (PPS or 1PPS) is an electrical signal that has a width of less than one second and a sharply rising or abruptly falling edge that accurately repeats once per second. PPS signals are output by radio beacons, frequency standards , other types of precision oscillators and some GPS receivers.

  6. Unit of time - Wikipedia

    en.wikipedia.org/wiki/Unit_of_time

    10 −12 s: One trillionth of a second. nanosecond: 10 −9 s: One billionth of a second. Time for molecules to fluoresce. shake: 10 −8 s: 10 nanoseconds, also a casual term for a short period of time. microsecond: 10 −6 s: One millionth of a second. Symbol is μs millisecond: 10 −3 s: One thousandth of a second. Shortest time unit used ...

  7. Programmable interval timer - Wikipedia

    en.wikipedia.org/wiki/Programmable_Interval_Timer

    The Intel 8253 PIT was the original timing device used on IBM PC compatibles.It used a 1.193182 MHz clock signal (one third of the color burst frequency used by NTSC, one twelfth of the system clock crystal oscillator, [1] therefore one quarter of the 4.77 MHz CPU clock) and contains three timers.

  8. Clock - Wikipedia

    en.wikipedia.org/wiki/Clock

    An analog pendulum clock made around 18th century. A clock or chronometer is a device that measures and displays time.The clock is one of the oldest human inventions, meeting the need to measure intervals of time shorter than the natural units such as the day, the lunar month, and the year.

  9. Timer - Wikipedia

    en.wikipedia.org/wiki/Timer

    A typical kitchen timer. A timer or countdown timer is a type of clock that starts from a specified time duration and stops upon reaching 00:00. An example of a simple timer is an hourglass. Commonly, a timer triggers an alarm when it ends. A timer can be implemented through hardware or software.