If you prefer, watch this video: Tone and Tone Squelch: The Basics
This video is very in depth with details of Tone and Tone squelch. Click here to get more information las you learn about Tone functions of the radio.
Now, to see Tones in action on a pair of radios: Click here to see Tones in action.
In many of the radios today, there is an options Squelch Mode. In the past when everything was Tone and we all communicated over analog systems, this field was not important. With today's repeaters being mixed with Digital and Analog and the use of DCS and Tone Squelch, this column is important to make those functions work properly.
First, though, let me explain Tone to make the explanation of Squelch Mode more understandable.
Tone - a signal that you cannot hear but that the repeater can hear is sent by the radio with the signal that carries your voice. When set properly, the repeater lets you voice transmission through to be retransmitted and heard by others on that frequency. If you are unsure of the information you have been given, use Tone. You will get into the repeater although you may hear some noise on the transmission that you hear. If the noise is too great or you are hearing people talk that you don't want to hear, change Tone Mode to TSQL
TSQL - Tone Squelch - now this is where the first confusion begins. Many folks, especially folks that have been in ham radio for quite a while refer to all of this as Tone Squelch... even when it is not. The repeater may have a tone required for you to be heard but it may not send out an unlocking signal with the return transmission. So while you are getting into the repeater, you are hearing NOTHING. Use this option ONLY if you know it to be necessary. If you are not sure, use Tone until you have a chance to test your settings with the repeater.
DCS - Digital Coded Squelch - NO, this is NOT for the DMR radios. They use something different. This is like TSQL and makes your radio block incoming signals unless they carry the same DCS value.
There are others, but these are the three needed for the following explanation.
Let's look at the options and see what they do:
Carrier - Should be used if the repeater (or simplex transmission) has no tone AND if you are using just Tone into the repeater.
CTCSS/DCS - Set if using TSQL (Tone Squelch) or DCS which transmits a tone to the repeater AND blocks incoming signals that don't carry a matching tone. Without this option set properly, TSQL or DCS will not work to block the incoming signal (or noise).
Optional Signal - Use to engage the option signal function to block and/or receive signals based on a DTMF, 2 Tone or 5 Tone system. The options for DTMF, 2Tone or 5Tone are set in the settings part of the file as necessary based on the instructions you are given for your particular system
CTCSS/DCS & OS - Both CTCSS/DCS AND Optional signaling are engaged. Your radio now requires that BOTH the CTCSS or DCS signal AND the DTMF, 2Tone or 5Tone signal match to control incoming signals heard and outgoing signals received by the repeater or other participating radios in this system.
CTCSS/DCS | OSBoth CTCSS/DCS AND Optional signaling are engaged. Your radio now requires that EITHER the CTCSS or DCS signal OR the DTMF, 2Tone or 5Tone signal matches to control incoming signals heard and outgoing signals received by the repeater or other participating radios in this system.
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