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-====== Precise frequency and clock signal generator GPSDO01A ======
-This design is focused to generating precise frequency signal with good long term stability for laboratory use. (As frequency and time normal GPS satellite clocks are used)
-This design is bypass product of developing [[en:rmds]] and [[cs:acounter|Atomic counter]].
-{{ :cs:designs:tools:gpsdo_prototype.jpg?400 |GPSDO01A prototype}}
-The output frequency can be stabilized anywhere in 10-810 MHz range.
-===== Device construction =====
-{{ :cs:designs:tools:gpsdo_system.png?500 |GPSDO01A block schematics}}
-Device consist following modules:
-  * [[en:clkgen]]
-  * [[en:clkhub]]
-  * [[en:clkdiv]]
-  * [[cs:ttlpecl]]
-  * [[cs:gps]]
-  * [[cs:pic16f87xtq44]]
-  * [[cs:usbi2c]]
-  * [[cs:lts]]
-===== Function principle =====
-Source of high frequency signal is free-running oscillator Si570 in module [[en:clkgen|CLKGEN01B]]. This module is connected to divider [[en:clkdiv|CLKDIV01A]] and  PIC16F887 MCU, which measures frequency of this oscillator.
-Interval of measurement is variable. Basic measurement calculates with  one second τ interval. (period of [[cs:gps|GPS01A]] PPS signal can be adjusted. Thus frequency measurement can be averaged over period in fraction of seconds or tens of seconds for long term stability measurement.)
-Measured data are stored in MCU memory and can be read by I²C interface. This is usually operated by host computer which computes frequency correction and apply a new frequency to si570 chip oscillator.
-Frequency correction method is in principle software defined and AVAR characteristics of this frequency generator system can be adjusted to meet application requirements.
-===== Related pages =====
-  * [[cs:time_sync]]
-  * [[cs:time_interval_counter]]
-===== References =====
-  * [[http://en.wikipedia.org/wiki/GPS_disciplined_oscillator|GPS disciplined oscillator]]
-  * [[http://www.febo.com/pages/stability/|Oscillator stability]]