General sense of sending or conveying:
* Reception: The act of receiving something.
* Blocking: Preventing something from being sent or received.
* Suppression: Holding back or stopping something from being communicated.
In the context of vehicle transmissions:
* Manual: A transmission system where gears are shifted manually.
* Direct drive: A system that eliminates the need for a transmission, directly connecting the engine to the wheels.
In the context of broadcasting:
* Reception: The act of receiving a broadcast.
* Silence: The absence of transmission.
To give you the most accurate antonym, please provide more context about how you are using the word "transmission."