2024-10-26 15:17:06 +00:00
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# PLC signal amplitudes
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To have comparable results, we measure the peak-to-peak voltage of the preamble of the homeplug packet.
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1. Homeplug modem with AR7420, supplied by 5V
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10Vpp at the transformer
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2. Homeplug modem with AR7420, supplied by 5V, with 150ohm series resistor between transformer and CP.
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Foccci v3 (including transformer with RIK10, 2x5 turns) connected via 1m twisted pair.
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3Vpp at the CP line
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3. Like 2, but in the homeplug modem two additional series resistors 680ohms in the transmit path, between
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the power amplifier and the transformer.
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- EVSE packet: 250mVpp at the CP line
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- Foccci packet: 500mVpp at the CP line
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4. Like 3, but in the homeplug modem the two 680ohm in serial and a 10ohm in parallel to the transformer.
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- Foccci packet: 500mVpp at the CP line (no change, normal)
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- EVSE packet: hardly measurable, in the 20mVpp range.
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- Communication still works perfect.
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5. Compleo 20kW triple charger
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Sends very loud packets, even if no vehicle is connected.
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17Vpp
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6. ISO 15118-3
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On both, EVSE side and EV side of the charging cable, the typical voltage is
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1.3Vpp.
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This is specified as "power spectral density" of typical -75dBm/Hz at 1.8MHz to 30MHz, receiver band width 9kHz with 50 ohms.
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Example states the following levels:
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- Transceiver output: -72dBm/Hz
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- CP on EVSE: -76dBm/Hz
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- CP on PEV: -78dBm/Hz
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- Transceiver modem input: -81dBm/Hz
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This would be 9dB between transmitter output and receiver input.
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2024-10-26 16:10:18 +00:00
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7. Output of the QCA7005
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4Vpp. Each output (TX+ and TX-) sit at ~1.6V statically, and move 1V up and 1V down. So the differential voltage
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reaches from -2V to +2V, which is 4Vpp.
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2024-10-28 18:09:42 +00:00
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8. Foccci 5.1 transmit level
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with 120ohm termination
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270mVpp
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9. Foccci 5.1 receive limit test
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- Foccci sees the EVSE, starting to become instable, if 400mVpp -36dB. This is 400mVpp / 64 = 6mVpp.
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- Foccci sees single messages, if 400mVpp -42dB. This is 3mV.
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- Foccci does not see the EVSE (modem goes to sleep) if 400mVpp -44dB. This is 400mVpp/158 = 2.5mVpp.
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2024-10-29 07:09:09 +00:00
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10. Foccci 5.1 transformerless patch, R25=100ohms, receive limit
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- 400mV -32dB stable connection.
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- 400mV -38dB still works, starting to become instable.
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- 400mV -44dB sometimes modem sleep, sometimes not.
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- 400mV -50dB modem sleep.
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11. Foccci 5.1 transformerless patch, R25=100ohms, transmit level
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210mVpp
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2024-10-28 18:09:42 +00:00
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# Attenuation calculator
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https://www.digikey.de/de/resources/conversion-calculators/conversion-calculator-attenuator
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* -6dB is half voltage
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* -12dB is quater voltage
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* -20dB is tenth voltage
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