Cal Factor

[pmelci]

Hi,

we have 8481a power sensor. On Chart there are frequencies and cal factors. for example at 1 Ghz , 99 % and at 2 Ghz , 98. 2 %

My question is :
which value should i use at 1. 5 Ghz ?
Is there any formula to calculate between 2 frequencies ?
or 1 Ghz cal factor is valid until 2 Ghz ?

Thanks. . .

[jimmyc]

Interpolation

In the mathematical subfield of numerical analysis, interpolation is a method of constructing new data points within the range of a discrete set of known data points

http://www.microwaves101.com/encyclopedia/linterp.cfm
interesting read on interpolation and some formula. 

[pmelci]

Thanks Jimmy.

While calibrating signal generator power flatness calibration , T. O.  says :
sweep between 2 - 6. 2 Ghz.  I am using 100 Mhz resolution.
At 2 Ghz , I adjust Power Meter Cal factor for example 99 %
At 3 ghz , I adjust Power Meter Cal factor for example 98 %

Should i calculate every point interpolated cal factor like 2. 1 ghz , 2. 2 ghz etc. .  ? total 42 point.

[Bryan]

If you are using something like a 437 or EPM you can enter the cal factors for your sensor in the table the instrument stores, then you just select frequencies and let the meter interpolate for you.

[CalibratorJ]

If you are using something like a 437 or EPM you can enter the cal factors for your sensor in the table the instrument stores, then you just select frequencies and let the meter interpolate for you.

That's the best way I have found to do it. I REALLY hate TOs and TBs that say to use a "specific" cal factor other than what is listed on the power sensor's data label, as cal factors can vary from sensor to sensor by quite a large difference. I've also seen a few procedures, both military and OEM, they don't even mention changing the cal factor on your power meter for the sensor. Yeah, depending on which sensor you are using, there could be HUGE differences between just using 100% and using the actual cal factor. Guess some procedures take into account that the tech SHOULD know to do that automatically......

[skidaddle skaduski]

I insert another vote to use a power meter that stores the calibration factors and interpolates for you.  If you don't have a meter that does so, then you can always set up a spreadsheet to do it for you.  I have found this useful because some power meters will only allow you to store so many power sensors.  Our lab has a handful so I'm always switching the CFs out with the one that just got back from OEM calibration.  I can send or make a spreadsheet for you if you wish.  Good luck.

CalibratorJ--- I noticed a few procedures which did not inform the technician to change the cal factors.  I've always took this as," Maybe if you don't know to change the cal factors, then perhaps you shouldn't be touching a power sensor and/or meter, let alone the unit they're being used on. "  :-D

Let me know if you want me