16 point calculation
The 16 point calculation is different for several standards. This document is meant for the programmer to understand the code better.
Some standards describe the removing of the measurement points before calculating the correct power. you can define how you want the remove the points.
Removal of points according to[edit]
EN 61000-4-3[edit]
- Where the 1995 version, the 1995, A1 version and the 2002 version, mention to throw away a MAXIMUM of 4 out of 16 points, the question arises if you should remove any points, as long a all test points to comply to the 0 – 6 dB criterion. No clear clue can be found in the text. However, one can imagine, taking all 16 points into consideration (even if all these points fall within the 0-6 dB criterion) will result in a higher calibration power level, and therefore a higher generated field.
- The goal of the above version will be to find a total of 12 points, which comply with the 0-6 dB criterion at one hand, and will result in 12 remaining points with the lowest differences between these points. For this purpose, one can either calculate the average fields of all 16 points one time, and then through away the four points which differ most from the average, or recalculated the average field every time one point has been thrown away. (I.e. calculated the average for 4 times). Again, it will be obvious, this will result in a different calibration file.
- Probably as a result of all the above issues, the EN61000-4-3, 2002, A1 version of the basic standard, uses a completely different approach in calculation which points to throw away. Instead of taking the average of the points, all points are place in descending order, and, starting from the highest power level (or, the lowest field strength level if performing a constant field calibration), check if the first 12 points are within the 0 to +6 dB criterion. If not, skip the first point and check if the following 12 points are within the criterion. This procedure is repeated (for a maximum of 5 times) unit the 0 to +6 dB criterion is met. This new method answers the questions above:
Issue 1: For all frequency points, 4 points are removed now. Issue 2: With the new approach, there is no discussion anymore Issue 3: The procedure for Constant power and constant field are now clearly described and will result in the same final calibration file for both methods. Issue 4: No alternative calculation methods are possible anymore. This method will result in de calibration file with the highest power level, which complies with the 0 to +6dB criterion.
1995[edit]
The 1995 method take the average of the power in dBm and then calculates the points that need to be removed.
2002[edit]
The 2002 method take the average of the field that is corrected for 1 Watt (30 dBm) and then calculates the points that need to be removed.
2002 A1[edit]
The 2002 amend. 1 it totally different then all the methodes before. Instead of taking the average of the points, all points are place in descending order, and, starting from the highest power level (or, the lowest field strength level if performing a constant field calibration), check if the first 12 points are within the 0 to +6 dB criterion. If not, skip the first point and check if the following 12 points are within the criterion. This procedure is repeated (for a maximum of 5 times) unit the 0 to +6 dB criterion is met.
ISO 11451-2[edit]
Open items[edit]
- What if I have 16 points and I want to remove 5 points? how do I configure that I want to average 5 times?
- What happens if I select 4 times?
Performing a 16 point calibration[edit]
To perform a 16 point field uniformity test the following steps need to be taken.
- Configure a 1 point calibration which will be performed on all the 16 points.
- Position the probe on the first position, and run the one point calibration.
- Move the probe to the next position.
- Run the 1 point Calibration
- Perform the 2 steps above untill all 16 points are done.
- Open a 16 Point calibration TSF
- Insert all the 16 single point into the test.