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en:acounter [2018/12/15 14:57] (current)
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 +====== ​ Atomic counter ​ ======
  
 +Atomic counter is a frequency counter designed for an accurate frequency measurements. It has a PPS output from GPS used as a frequency normal ((GPS satellites have several atomic clocks onboard, hence the name ‘atomic’ counter)). Its construction is now implemented in two variants:
 + 
 +  * ACOUNTER01A -  Produced using [[en:​s3an|FPGA board]]
 +  * ACOUNTER02A - Produced using microcontroller [[en:​pic16f87xtq44|PIC16F887]] and several other modules.
 +
 +Accuracy of both variants is determined by a used GPS and a quality of incoming signal. However, generally, each measurement needs to be averaged over a longer time period, because the time stamps only have a short-term accuracy in order of tenths of ns. Individual measurements can therefore have a relatively wide Gaussian scattering, which has to be eliminated by averaging. ​
 +
 +===== ACOUNTER01A =====
 +
 +{{ :​cs:​designs:​tools:​atomiccounter_big.jpg?​direct&​300 |}}
 +
 +This version work up to approximately 600 MHz.
 +
 +==== Construction ====
 +
 +Atomic counter contains following modules:
 +
 +  * [[en:​s3an|S3AN01A]]
 +  * [[en:​gps|GPS01A]]
 +
 +===== ACOUNTER02A =====
 +
 +{{ :​cs:​designs:​tools:​acounter02a.jpg?​direct&​300 |}}
 +
 +Using [[en:​clkgen]] module, a functionality up to at least 850 MHz has been verified. However, as the divider'​s input [[en:​clkdiv]] works up to 3 GHz, we expect the counter to be operational up to this frequency. ​
 +
 +===== Related articles =====
 +
 +  * [[en:​gpsdo]]
en/acounter.txt · Last modified: 2018/12/15 14:57 (external edit)