Atomic counter is a frequency counter designed for an accurate frequency measurements. It has a PPS output from GPS used as a frequency normal ¹⁾. Its construction is now implemented in two variants:

• ACOUNTER01A - Produced using FPGA board
• ACOUNTER02A - Produced using microcontroller 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.

This version work up to approximately 600 MHz.

Atomic counter contains following modules:

• S3AN01A
• GPS01A

Using clkgen module, a functionality up to at least 850 MHz has been verified. However, as the divider's input clkdiv works up to 3 GHz, we expect the counter to be operational up to this frequency.

• gpsdo