Does the standard termination of 120 ohm really suppress reflections in recessive state in CAN?
When any signal is sent into an infinitely long transmission line, the signal sees the characteristic impedance all the time so there is no discontinuities and no reflections. If you have a bus of certain length, then the signal sees the bus to have the characteristic impedance until the signal hits the end which has infinite impedance - a discontinuity. Therefore the ends are terminated with a resistor matching the characteristic impedance so that when the signal reaches end of the wires, it will still see from that point on the resistor impedance which is no different from the impedance of the infinitely long transmission line. So correctly terminated transmission line has no reflections from the ends, no matter what signal is sent into it. The reflections do not depend on what signal is sent to the bus and at what source impedance - the dominant state drives the bus with extremely low impedance, and the recessive state stops driving the bus so it has extremely high impedance. Basically same as connecting a voltage source ( e.g. battery) to the bus, and disconnecting it. The CAN bus will look like a 60 ohm resistance, from any point.