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E4416A power meter - sensor calfac. tables

Question asked by RAVONCAPD on Nov 1, 2009
Latest reply on Mar 31, 2011 by RayH

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We have an Agilent E4416A power meter with firmware version A1.04.08. While I know the power meter is supposed to load the sensor's cal. fac. table automatically when I connected a 8482A sensor it did not seem to do so, the 8482A cal fac table in the power meters memory did not match the one on the sensor and the default table has only a ref. cal of 100%. This remains the same after preset and after preforming zero+cal.

Channel setup after preset is:
Sensor Mode: AVG only(greyed out)
Range: AUTO(greyed out)
Filter: Auto
Duty Cycle: Off
Offset: Off
Cal Fac: 100.0%
CF Table: Off
FDO Table: Off
Video Avg: Off (greyed out)
Video B/W: Off(greyed out)
Step Detect: On

What are the settings supposed to be for the power sensor and how large an error would a wrong cal. fac. generate? Also how can I check if the power meter did in fact recieve the sensor's cal fac. table correctly?

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odanzy Nov 2, 2009 6:27 AM
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The standard 8482A does not have internal EEPROM, so it cannot provide the cal factors to the meter. With this sensor, you still need to manually enter the cal factors into the meters. There is a newer version of the 8482A, the N8482A which has two options: 1)STD - this has the EEPROM inside and can load sensor cal factors into the meter and 2)CFT - this does not have EEPROM and the cal factors must be manually loaded.
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RAVONCAPD Nov 2, 2009 10:11 PM
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I see, thank you.
That explains why the power meter didn't seem to be loading the table automatically and I had to input it manually. So what are the settings supposed to be for the power sensor and how large an error would a wrong cal. fac. generate? Also how can I check if the power meter did in fact recieve the sensor's cal fac. table correctly?
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lynchdavidb Nov 5, 2009 3:18 PM
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The error caused by using the incorect Cal Factor is totally dependant on the value of the cal factor that applies to the power sensor you used at the frequency of interest versus the cal factor that was actually loaded into the power meter. The cal factors for power sensors are shown as a linear value (as a percentage.) So any error between the two values would also be linear.

For example if the cal factor for a power sensor at 1 GHz was 99, but the value loaded into the power meter was 100, then you would have a -1% error. If you were measuring a 0.001 watt RF signal (1 mW or 0 dBm) the power meter would actually display a value 1% lower or .00099 W. In dB a 1% error is about 0.05 dB error. So instead of reading 0 dBm on the above example you would be reading -0.05 dBm

You can either enter the cal factor into the E4416A as a single frequency and value by pressing the hard key [Frequency/Cal Fac] and manually enter the value using the softkeys. Or you can setup the table by pressing the hardkey [System] then press the softkey {Tables} > {Sensor Cal Tables}. You can then select the table for your specific sensor, or create your own custom table. Go to your specific table and press {Edit Table} and you can now see the values that are entered into this table. You can change them if necessary.
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RAVONCAPD Nov 10, 2009 1:47 AM
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Thank you. That explanation makes it easy to tell if the sensor is reading correctly.
I guess I wasn't clear about my problem with getting the correct cal table. The question is not how to enter the values, but rather after having entered the correct values into the table what settings do I need to change so that the power meter will read the cal. fac. values from the table in question?
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lynchdavidb Nov 12, 2009 3:07 PM
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If you go to the same location where you saw the sensor cal factor tables. To do that press the hardkey [System] then press the softkey {Tables} > {Sensor Cal Tables}. You can then select the table for your specific sensor by highlighting it with the up/down keys. Once you have highlighted the table you want to use for your sensor press the softkey {A Table On Off}. This will turn the highlighted table ON or OFF for your sensor.

You can confirm this by going to the [Channel] key. Look halfway down the display to the entry "CF Table". It should be displaying the cal factor table you selected. That's all there is too it.
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Jacko Mar 30, 2011 8:42 AM
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Sorry - probably I a bit slow and need to ask... When using E4416A + 8482A with manually set cal factor table into E4416A do I need to set the measurement frequency to get the right reading or is E4416A automatically using the right cal factor form the table (which I keyed into E4416A)? E.g. If I am measuring 1GHz signal with 8482A do I have to key into E4412A that the frequency is 1GHz to get he right treading?

Is it the same case with E4412A power sensor?

BR, Jaakko
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RayH Mar 31, 2011 8:32 AM
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yes - you do need to set the frequency. The meter has no way to measure frequency, it must be entered by the user.

This is true for both a manually entered table (8482A) or a table from sensor memory (E4412A).
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E4416A power meter - sensor calfac. tables

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