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Entry  Fri Apr 15 12:17:39 2011, kiwamu, Update, LSC, 11MHz demod board : funny I-Q phase relativephase.png
    Reply  Fri Apr 15 15:15:08 2011, kiwamu, Update, LSC, 11MHz demod board : 90 degree splitter 
       Reply  Sat Apr 16 02:00:14 2011, rana, Update, LSC, 11MHz demod board : 90 degree splitter 
          Reply  Mon Apr 18 13:05:57 2011, kiwamu, Summary, LSC, demod board modification demod_board.png
             Reply  Mon Apr 18 14:11:44 2011, kiwamu, Update, LSC, RF status RF_Work_Status.png
             Reply  Thu Apr 21 21:24:41 2011, kiwamu, Update, LSC, demod board : new 90 deg splitter DSC_2949_ss.jpgDSC_2951.JPGDSC_2952_ss.jpg
                Reply  Thu Apr 21 21:46:22 2011, kiwamu, Update, LSC, demod board : new 90 deg splitter relativephase.png
                   Reply  Fri Apr 22 11:08:50 2011, kiwamu, Update, LSC, demod board AS11 : amplitude imbalance IQamplitude.png
Message ID: 4533     Entry time: Fri Apr 15 15:15:08 2011     In reply to: 4530     Reply to this: 4537
Author: kiwamu 
Type: Update 
Category: LSC 
Subject: 11MHz demod board : 90 degree splitter 

[Rana, Koji, Kiwamu]

 Moreover the amplitude of the I and Q signals are highly unbalanced, depending on the LO power again.

This implies the coil for a 90 degree splitting won't work at 11 MHz since the coil is home made and used to be designed for a specific frequency (i.g. 24.5 MHz).

We decided to use a Mini circuit 90 deg splitter instead. Steve will order few of them soon and we will test it out.

Quote:

During checking the 11MHz demod boards I found that the I-Q relative phase showed funny LO power dependence.

It is now under investigation.

 

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