Electromagnetic compatibility of transmitter, receiver, and communication port of a space-qualified laser altimeter

This paper reports on EMC issues of the laser transmitter, the photodiode receiver, and the communication port of the BepiColombo Laser Altimeter BELA during integration on ESA's Mercury Planetary Orbiter MPO. Parasitic currents originating in the active Q-switch electronics of BELA's diode-laser pumped Nd:YAG laser and from the high-power laser diode driver electronics interfered with the sensitive Si avalanche photodiode sensor operating at a noise floor of about 0.3 pA/VHz in a bandwidth of 20 MHz, and with BELA's Spacewire port, corrupting about 3% of telemetry data to the MPO memory. The problems had been eliminated by implementing multi-point grounding.