1) Asker 2) Enquirer 3) Inquirer 4) Inquisitor 5) Querier 6) Questioner 1) Asker 2) Inquisitor 3) Interlocutor 
• (n.) One who asks questions; a questioner.
In an automatic identification system employing RF, the device, which triggers the identifying, tags to respond with a modulated RF message.
In·ter'ro·ga`tor noun [ Latin : confer French interrogateur .] One who asks questions; a questioner. 
Interrogator An RFID reader. See Reader for more info.
A radar transmitter which sends out a pulse that triggers a transponder. An interrogator is usually
a person who interrogates. · Also calleda transmitter that emits a signal to trigger a transponder.