Guardian Telecom Inc.
Installation & Operation
TBA Models
Page 7
4.
System Overview
The Talk Back Amplifier (TBA) is so named because of the ability for the user to talk back to the
speakers instead of using a separate microphone to talk back.
The model TBA is an intercom system designed for use in situations where frequent communications
between two or more stations are required.
The TBA system utilizes speakers in two modes:
as a speaker output to broadcast audio messages from other stations
as an audio microphone to pick up audio messages.
4.1. Central Station
The Central Station speaker normally outputs audio coming from the Monitored Station.
The audio from the Monitored Station or Stations #1, #2 or #3 with their PTT depressed, will be
output on the Central Station speaker.
To output audio the Central Station user presses the Press to Talk (PTT) switch. The Central
Station PTT switch is normally mounted on the microphone housing, but it may be a foot switch.
The Central station is different from the other stations in that it has a separate microphone input as
well as a speaker output. The Central Station speaker also has a low level “sidetone” audio from
the speaker to allow the user to hear that the Central Station audio output is working.
The Central Station console consists of a (goose neck) dynamic microphone and a hand switch or
pedal switch for PTT. The Central Station has the highest priority in using PTT. When the Central
Station PTT switch is engaged (depressed) the TBA puts a low level audio onto the Central Station
speaker. This low level is to prevent acoustical feedback. The other speakers in the system are set
to the speaker mode and output audio coming from the Central Station.
4.2. Monitored Station
The Monitored Station is different from the other stations in that it will continuously send the audio
heard at its speaker to the other stations when no Press to Talk (PTT) switch in the TBA is
depressed. The Central Station and up to three stations normally output audio coming from the
Monitored Station to their speakers.
The PTT switch on the Monitored Station is used only as a “Ringing” or Alert Tone activation.
Pressing the Monitored Station PTT will stop the audio output from the Monitored Station and put a
“Ringing” tone onto the Central Station, Monitored Station and the other stations’ speakers.
The Monitored Station speaker will output the audio coming from another station if the other station
presses a PTT switch. When the Monitored Station speaker is outputting audio it does not send
audio to the other stations. The Monitored Station speaker will change from a microphone input
into a speaker output when the Central Station or another station has the PTT switch pressed.
4.3. Stations #1, #2 and #3
The Stations #1, #2 and #3 have a speaker and a PTT switch. The audio from the Monitored
Station or any other station with a PTT depressed will be output on that station’s speaker. When
the station’s PTT switch is depressed the station will output audio to the other stations. When the
speaker is outputting audio it does not receive audio from the other stations.
