Specifications

Appendix D – Manufacturing Test and Handling Guidelines
240 PL 3120/PL 3150/PL 3170 Power Line Smart Transceiver Data Boo
k
Figure D.2 Test Cycle Waveforms
Notes on Missed Messages
Due to the adaptive sensitivity algorithms inside the PL Smart Transceiver, it is statistically possible for a good
transceiver to miss a single packet. Therefore the test should be repeated two more times if the initial test fails. If the test
passes in two out of three tries then the UUT is good. If the UUT passes in only one out of three times then the UUT
should be considered marginal and should be verified by way of the procedure in Chapter 7. A UUT that fails three or
more tests is defective.
Test System Verification
This section is intended to describe a verification procedure that should be performed on the production test system in
order to ensure repeatability of the power line physical layer test. The procedure includes:
• Verification of background noise in the test system
• Verification of Query ID message amplitude
Verification of Background Noise
One of the functions of the test system isolator is to prevent noise from the power mains from disturbing the test results.
The test system is designed to transmit a Query ID message that has been attenuated by approximately 70dB. The
amplitude of the 70dB-attenuated message should be about 2mVp-p. In order to consistently test that UUTs can receive
this low level signal, the background noise of the test system must be at least 6-9 dB lower than the attenuated message.
It is important to note that only noise at or near the PL Smart Transceiver’s communication frequencies affect the
reproducibility of the test. The power line isolator is designed to filter noise in the PL Smart Transceivers
communication frequency range. The isolator does not, however, filter low frequency noise to a level that is 80dB below
the PL Smart Transceiver’s transmit level. In fact it is not uncommon to observe low frequency noise on the order of
1Vp-p passing through the isolator. A consequence of this fact is that the background noise level must be measured with
a frequency-selective instrument.
D/A signal
QueryID message send to UUT
before attenuation
A/D signal
Trigger signal
QueryID message seen by the
UUT (70dB attenuation)
Response from
UUT to QueryID
message into
5 ohm load
7V p-p