Hello Group,
We recently had a device go through a test house that required a conducted
measurement on the DC input port for CISPR 22 that made me think about the
validity of the test measurements. Lets say you have a radio receiver that
gets its power from some Auxiliary equipment. There are also some data lines
with signal common going to/from that auxiliary equipment. If I insert a
LISN in the DC power lines to take a conducted reading on the radio receiver
power input I have a measurement problem. Because the common of the data
signals is really the same net as the negative DC lead, then if I leave the
data signal common in place, I am, in effect, shorting out the 50uH inductor
portion of the LISN on one side. How does one get around this problem? Do
you just accept the reading made in this manner? Remove the signal commons
(somewhat of a problem to signal integrity :-))? Add LISNs to all other
signals using common (also not very good for data integrity and what about
the fact that the 50uH coil in each common leg of the LISNs would now be
in parallel with the number of LISNs you are using.)? Your thoughts on this
topic are appreciated.
Regards,
Kevin Harris
-------------------------------------------
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.
To cancel your subscription, send mail to:
[email protected]
with the single line:
unsubscribe emc-pstc
For help, send mail to the list administrators:
Jim Bacher: [email protected]
Michael Garretson: [email protected]
For policy questions, send mail to:
Richard Nute: [email protected]
