Log entry time 09:10:49 on February 08, 2012

Entry number 362160

For bcm signal, we need to take three copies: 2 happex and 1 V2F which go
to scaler, the bcm signal is about 0~5V. Right now I just use BNC T
splitter to split the signal. But I found that it will reduce the
resolution of asymmetry test.
I tried to take different copies with that BNC T splitter, and you can
see how it reduce the resolution of asymmetry in attachment. If I just
connect to 1 happex ADC or split it to 2 happex ADC, the resolution is
pretty good, RMS is just 8ppm. But while I tried to split it to 1 happex
ADC and 1 V2F or split it to 2 happex ADC and 1 V2F, you can see the
asymmetry result will have 2 peaks and RMS rise to about 85ppm.
Kalyan and I also tried to see the reflection signal from happex and V2F
by using pulser, you can see the picture in attachment. I think this is a
big problem, since bcm signal is too high, NIM module can not be used for
split it.

1 happex

2 happex

2 happex and 1 V2F

1 happex and 1 V2F

reflection from happex

reflection from V2F

reflection from happex and V2F