IF2 Programmable Gain linearity


The downstairs if2 has an 11 db step attenuator (1db steps) followed by 3 10 db amplifiers. These amplifiers can be switched in/out under computer control.
On 27nov06 the linearity of the programmable gain was tested using the 327 receiver looking at the sky. The programmable gain was stepped from -11 db (atten all the way in) to +30db (the 3 amps switched in). At each 1 db step the power in polA and polB was measured using the power meter and recorded.
The plots show the power in the IF2 while the gain was stepped (.ps) (.pdf):
We should fix the 3rd amp to be closer to 10db. The datataking tries to adjust the power levels using the current settings and the measured values. A discontinuity of 4.5 db will mess up this algorithm.
Processing: x101/061127/rdpwrif2.pro
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