Equalizing gain to group0,group 1 spectrometers


19jan09:Before attenuators installed.
16feb09:After attenuators installed.


    The pdev spectrometer is split into two groups of 7 boxes. Group 0 is the primary observer and group 1 is the commensal observer. The signal path is:
There is only 1 variable attenuator (per freq band) that is used for both group 0 and group 1.  When adjusting the power levels, the attenuators are set using the values from the group 0 read back. Any gain differences after the baseband output split will cause the power levels for group 1 to be a little off.

Grp0,1 gain dif before attens added.

    Data was taken on 19jan09 to measure the gain difference after the baseband splitting of the signal in the bbm. This was prior to inserting 1db pads to equalize the gains: The setup was:
The plots show the results of the rms, mean measurements (.ps) (.pdf):

Grp0,1 gain dif after 1db pads added.

    The 1db pads were inserted in the digitzer path specified above on 20jan09. Data was taken on  16feb09 (after b6s1g1 dig i0<->q0 were unswapped inside the spectrometer box). The if2 noise source was used. The cal.conf file was generated  before taking the data. Data was taken as described in 19jan09.

The plots show the results of the rms, mean measurements (.ps) (.pdf):

processing: x101/090119/getrms.pro

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