User`s guide

LONWORKS FTT-10A Transceiver User’s Guide A-7
FTT-10A scans. The FTT-10A control module PCB design followed the layout
guidelines shown in chapter 2 of this user’s guide.
No ferrites or other EMI suppression devices were placed in line with the network
connection. The Neuron Chip in the control modules was programmed to rapidly
transmit short-length explicit messages. The network traffic level was about 80
packets per second when the DUT was running at 5MHz, and about 140 packets per
second when the DUT was running at 10MHz. There were approximately 1 or 2
collisions per second between the DUT and the Echo Unit.
The radiated EMI comparison scans were performed at both 3m and 10m test
distances. The 3m test distance (as measured from the test table to the receiving
antenna) is used to assess compliance with FCC requirements, while the 10m test is
used to assess compliance with EN 55022 requirements. The ANSI C63.4 test
procedure was used for all of the test scans.
The results of the comparison scans are shown in figure A.4 and A.5. Figure A.4
shows the results of the comparison scans performed with the test antenna placed 3m
away from the test table. Both the FTT-10 and FTT-10A transceivers demonstrate
compliance with the FCC-B limit with margin. Figure A.6 shows the results of the
comparison scans performed with the test antenna placed 10m away from the test
table. Both the FTT-10 and FTT-10A transceivers demonstrate compliance with the
EN 55022-B limit with margin.
Figure A.5 also contains test data for the SLTA-10 adapter operating at 10MHz. The
SLTA-10 adapter test results are discussed in the next section.
0
20
40
60
80
10 100 1000
Frequency (MHz)
5MHz FTT-10 5MHz FTT-10A 10MHz FTT-10A
Field (dBuV/m)
FCC-A
FCC-B
Figure A.4 EMI Scan Data at 3m Test Distance for FCC-B Compliance