Forgot to mention --- I switched two ADC and BIO cables that were connected to the whitening filter of a quad demodulator in ISC R3 rack. This is due to the special modification on the demodulator.

At the very bottom of the rack, there is a quad demodulator which takes care of 18, 90 and 45 MHz LSC signals. From channel 1 to 4, the order of the demodulation frequencies should be 18, 90 and 45 MHz in order to satisfy the planned cable layout (see for example D1200666). However, this quad demodulator (S1001003) has these signals in order of 45, NAN, 18 and 90 MHz. The point is that this is a special mod version, where it has a fancy diplexer in it. So you can not easily swap the modulation frequencies between the channels unless one opens up the box and physically allocates the position of the boards. Because of that, the signal at the ADC were screwed up. For example, I obtained a signal from 18 MHz demodulator at a digital channel which was dedicated for 45 MHz (i.e. LSC-AS_A_RF45). In order to quickly fix it, I decided to swap the two ADC cables that were connected to the back side of the whitening filter. This pf course lead to another modification -- I had to swap the BIO cables.