Squelch Mode - An option that cannot be ignored

Many... Many radios have in their memory channel programming an option for Squelch Mode.  This is in addition to Tone Mode that you have used for a long time.   The Squelch Mode setting controls the functionality of Tone Mode TSql (Tone Squelch).

The options for Squelch Mode include:  

• Carrier (the default)
• CTCSS/DCS  (TSql and DCS)
• Optional Signaling (DTMF, 2Tone and 5Tone)
• CTCSS/DCS & OS (Tone Decode and Optional Signaling)
• CTCSS/DCS | OS (Tone Decode or Options Signaling)

Squelch Mode must be set to CTCSS/DCS for Tone Decode to work.  Tone Decode (T Sql) works to mute incoming signals on your radio.  Only those signals with a matching CTCSS frequency will be heard. 

Squelch Mode set to Carrier allows your radio to hear ALL incoming signals regardless of the settings for CTCSS (for a radio with one available CTCSS frequency) or RX CTCSS (for a radio with two CTCSS frequency values available) vs the CTCSS value on the incoming signal.   Note: In proper operations, these must match for the radio to hear the signal. 

With all of this said, if you know that the Tone Mode set to T Sql and the receive CTCSS frequency is  set properly but you are still hearing all transmissions, set Squelch Mode to CTCSS/DCS and try again.  

Remember, your best testing is with another radio transmitting on the receive frequency of the radio in question with the CTCSS frequency set to match that of the radio being tested. Then to see T Sql work, change the CTCSS frequency on the transmitting radio and listen as the radio being tested ceases to hear the signal.  This can all be done easily in VFO on the transmitting radio.  

As of the date of this article, this option is not seen in Yaesu, Kenwood, Alinco or Icom radios.  It is found in radios from Baofeng, Btech, Anytone, Radtel, and many others.  Watch for it in your particular model.  It is not general across a line of radios, it is specific to a particular model.

03/21/2024