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For the highest accuracy possible, calibration may still be performed. This may be useful in the case where there are marginal failures. In addition, calibration values are now stored. This allows multiple wander transfer tests to be performed with only one calibration run (compared to previous versions where calibration had to be performed each time).
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In Paragon-X software version prior to X.10.40, calibration was mandatory step prior to performing the transfer test. This results in very long test times because each frequency point is effectively tested twice: once for calibration and once with the DUT in place. In X.10.40, calibration has been made an optional step. The absolute accuracy of Paragon-X generation and measurement is such that the G.8262 tests can be made accurately without calibration. For the highest accuracy possible, calibration may still be performed. This may be useful in the case where there are marginal failures. In addition, calibration values are now stored. This allows multiple wander transfer tests to be performed with only one calibration run (compared to previous versions where calibration had to be performed each time). |
Testing using a Single Frequency
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using
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a
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The frequency and pk-pk amplitude are specified in the UI. Clicking Generate Wander starts the generation of this tone; the measurement then runs for 10 seconds. The pk-pk output amplitude is measured across the full 10 second capture. The gain is then calculated and the result presented on the UI.
The measurement method for single sine has not changed in X.10.40
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Single Frequency
Using Paragon-X, a wander transfer measurement can be made using either a single frequency or a table of frequencies. For a single frequency:
The frequency and pk-pk amplitude are specified in the UI. Clicking Generate Wander starts the generation of this tone; the measurement then runs for 10 seconds. The pk-pk output amplitude is measured across the full 10 second capture. The gain is then calculated and the result presented on the UI.
The measurement method for single sine has not changed in X.10.
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40
Testing using a Table of Frequencies
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These assumptions then allow us to set lower and upper limits as shown in the diagram below:
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These limits are made optional so as to preserve backwards compatibility with previous software versions - the Lower Limit is disabled by default.
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Since each step has a recovery time, this also changes the minimum allowed Dwell Time for a step.
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| title | Table of Frequencies |
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Using Paragon-X, a wander transfer measurement can be made using either a single frequency or a table of frequencies. Details about table operation is given below.
The main changes in X.10.40 are:
New Enhanced Defaults for Option 1 clocks with optimised dwell times
New Lower Limit, with both Upper Limit and Lower Limit checking now optional
A Recovery Time has been added to each step
Enhanced Defaults
A new set of defaults has been added to provide a quick way to get extended frequency coverage and optimised test time. These defaults are recommended for testing Option 1 clocks to G.8262.
Limits
G.8262 does not completely specify the filter to be implemented. In order to establish performance limits, the following assumptions have been made:
The minimum gain in the pass-band is -3dB
The filter is first-order with 20dB/decade roll-off
These assumptions then allow us to set lower and upper limits as shown in the diagram below:
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These limits are made optional so as to preserve backwards compatibility with previous software versions - the Lower Limit is disabled by default.
Recovery Time
Some DUTs will have a transient response caused by the frequency and amplitude changes between steps in the table. This response will result in incorrect pk-pk amplitude measurements and so should be ignored when making measurements.
In X.10.40, recovery times have been added as shown in the table below:
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Frequency (Hz)
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Recovery Time (s)
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>35Hz
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0s
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15Hz to 35Hz
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5s
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4Hz to 15Hz
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20s
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<4Hz
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50s
For example, for any frequency less than 4Hz, the first 50 seconds of the measurement will be ignored and the pk-pk amplitude will be calculated over the remaining capture period (as defined by the Dwell Time)
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Note: The restriction on recovery time based on frequency is due to an internal hardware constraint in Paragon-X. This is not an issue for devices testing against G.8262.
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