TB8100 Service Kit User’s Manual Subaudible Signalling 7Subaudible SignallingThe TB8100 base station can transmit and receive using subaudible signalling.Both CTCSS tones and DCS codes are supported. CTCSS attaches asubaudible tone to the carrier signal. DCS attaches a digital code. A receiverprogrammed with a particular tone or code will not unmute unless that tone orcode is presented with the RF signal.CTCSS tones and DCS codes are referred to collectively as subtones. Subtonesmake it possible for different groups of users to operate on the same channelwithout hearing or disturbing each other. The base station and the radios thatuse it need to be programmed with the same subtone(s). In some parts of theworld, the use of subtones is regulated.AssigningsubtonesYou assign a receive and a transmit subtone to a channel by editing the channeltable. When the base station is operating on that channel, it opens the receivergate to signals with the receive subtone and transmits using the transmitsubtone.If the base station has a license for the Advanced Profiles and Task Managerfeature set, you can use a custom signalling profile to assign up to 16 subtonesto a single channel. The receiver recognizes any of the assigned tones andresponds according to its configuration for the particular tone. It can transmitthe signal (encoding it with the same subtone), transmit the signal (with adifferent subtone), or carry out a Task Manager action. You can also add anaudible reminder tone to the transmissions (for example, for customers who arebehind with their payments). The 16 subtones can contain CTCSS tones andDCS codes.Matching DCScodesMatching the base station’s DCS code to the code programmed into a group ofradios can be tricky. This is because the polarity of a DCS code can becomeinverted. For example, a radio has a DCS code of 017 but the base station mayneed to be programmed with 050 (017 inverted). Either use simple trial anderror to see which code works, or make test calls on the radios while runningthe base station’s subaudible scan diagnostic test, to find out what codes the basestation is receiving.Advanced options The base station always transmits a DCS end tone for muting the receive audio,but transmitting a CTCSS reverse tone burst is optional and configurable. Thebase station receiver can also be configured to respond to reverse tone bursts ifthey are expected.
