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The reference frequency was stepped in 10 KHz increments from 110 to 300 KHz approximately every 10 seconds. The GPIO cards were configured to count the number of of tics from the onboard 20 MHz clock tics while counting 10000 10,000 input cycles. These counts are repeated every 0.1 seconds. The resulting frequency measurements were then compared against the reference frequencies.
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*max(abs(fcor-fref))*is the maximum absolute difference of the measured, clock corrected frequency from the reference frequency for the 100-300 points at each reference. This maximum error seen in the test stayed below the 1:106line except for one point at 290 some points at frequencies over 200 KHz. The maximum error also stayed below the frequency discretization level, suggesting that after the clock is corrected, the remaining error is due to the discretization.
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