Specifications

PL 3120/PL 3150/PL 3170 Power Line Smart Transceiver Data Book 237
Transmitter Performance Verification
Transmitter performance is verified by causing the unit under test to transmit a packet into a low impedance load
(approximately 5 ohms), and then verifying that an acceptable amplitude signal is produced.
Initiating a Packet Transmission
A simple way of causing the PL Smart Transceiver-based device to transmit a packet is to communicate with it over the
power mains connection using a standard network management command. For instance, if a Query ID message is sent to
the UUT the PL Smart Transceiver will respond with an “ID Response” message over the mains connection. This
approach always works if the PL Smart Transceiver is an un-configured state and authentication is not enabled. If the
UUT is in a configured state and has authentication enabled an alternate method of initiating a packet must be used.
Measurement Time Window
The ID Response message consists of a preamble followed by the unique 48 bit Neuron ID (NID) that was programmed
into the PL Smart Transceiver when it was manufactured. Because each NID is unique, the RMS voltage of the transmit
signal from the PL Smart Transceiver will vary from unit to unit when averaged over the entire transmitted packet. In
order to provide a reproducible test, the transmit signal amplitude (V
RMS
) of the UUT should only be measured during
the initial preamble of the ID Response message. The preamble spans the first 35 bit times of the ID Response message.
The first 35 bit times of the packet will be identical for all UUTs, independent of their unique NID.
The duration of the first 35 bit times varies depending on whether the product is operating in C-band or A-band as
follows:
C-band 35 bit times = 6.36ms
A-band 35 bit times = 9.70ms
Transmit Signal Amplitude
While transmitting into the ~5Ω load (described later in this chapter), the PL Smart Transceiver should produce an
output signal of approximately 1V
RMS
during the first 35 bit times of the service pin message (see Table D.1 for
suggested test limits). The suggested test limits allow for normal production variability and should not have any further
guard band added.
Receiver Performance Verification
Receiver performance is verified by sending a highly attenuated message to the UUT and verifying that the device
responds to that message. The attenuated message is transmitted from an appropriate D/A card (such as the National
Instruments PXI-6070E) using a waveform file supplied by Echelon. The response by the UUT to the attenuated
message can be used for transmitter performance verification. It is not necessary to validate the contents of the response
packet. The fact that the response packet was transmitted by the UUT indicates that the attenuated message was
correctly received.
In order to have reasonable assurance that the UUT can receive packets with acceptable sensitivity, the receive test
message is attenuated by approximately 70dB using the interface circuit described below (where attenuation =
20log
10
(Vin/Vout)).