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Different output powers when running a IQ modulated sequence compared to individual segments.

Question asked by Deep on Jul 1, 2016
Latest reply on Jul 1, 2016 by EricBaker

Hi,

 

I have a question regarding the power outputs of the PSG E8267D model with I/Q modulation using the internal baseband generator (BBG1, option 602).

 

I upload two different waveforms to the volatile memory on the device. When I play these waveforms I measure a certain output power equivalent to a 1.6 Vpp into a 50 ohm load. However, when I play a sequence that is a concatenation of both these waveforms I measure a different power equivalent to 1.89 Vpp into a 50 Ohm load. In both thee cases the value on the IOUT (rear panel) are identical.

 

My PSG is quite old, I have firmware version C.06.10 dated March 01 2011 could this be the problem? Additionally the device has not been calibrated for ~4 years.

 

I have tested the same functionality on a brand new device of the same model which has recently been bought by the lab and this problem does not exist.

 

I am a bit wary of upgrading the firmware myself in case I permanently freeze the signal generator if there is an error during upgrade. Does the upgrade utility have features to avoid this happening?

 

Maybe I'm just missing one of the IQ settings that assigns a particular value in the IQ waveform to a certain RF power?

 

Any help appreciated.

 

Thanks

Sandeep

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