Based on the description from TacOps ARAD missiles home on anything that transmits in the battlespace and it gives a list, but the current topic discussion brought two questions to mind.
The Angel ECM interferes with Streak SRMs so that it is not an automatic hit with all the missiles. By the description of the Streak missiles, the whole flight receives telemetry updates from the launcher & its own targeting system.
Should active Streak SRMs & LRMs also attract ARAD missiles?
Per how Stealth Armor works now, the ECM is used to keep a mech, veh or BA's own transmissions trapped inside the armor- why C3 does not work when Stealth Armor is active. I am not sure, either in rules or even design, we ever had any sort of discussion about Stealth Armor stopping Artemis telemetry links on missile launchers which would be the same in principle.
Does active Stealth Armor negate the ECM's targeting bonus for ARAD missiles- IE Stealth Armor is not a valid target for the bonuses?