the cause of error "l1ctl.c:238 Dropping frame with 93 bit errors"

[Chengcheng Gou]

I am running the ccch_scan, and the error occurs:

<000c> l1ctl.c:238 Dropping frame with 93 bit errors
Dropping frame with 84 bit errors
<000c> l1ctl.c:238 Dropping frame with 84 bit errors
Dropping frame with 83 bit errors
<000c> l1ctl.c:238 Dropping frame with 83 bit errors
Dropping frame with 86 bit errors
<000c> l1ctl.c:238 Dropping frame with 86 bit errors
Dropping frame with 85 bit errors
<000c> l1ctl.c:238 Dropping frame with 85 bit errors
Dropping frame with 71 bit errors
<000c> l1ctl.c:238 Dropping frame with 71 bit errors
Dropping frame with 78 bit errors
<000c> l1ctl.c:238 Dropping frame with 78 bit errors
Dropping frame with 80 bit errors
<000c> l1ctl.c:238 Dropping frame with 80 bit errors

in which situations the error may appear? Does anyone know?
Thanks!