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CTCSS (tone squelch) on TX & RX?

Mark K9BOO
Mark K9BOO Member
edited April 2020 in SmartSDR for Windows

Forgive me if I missed the answer in my search of prior posts, but I wanted to find out if CTCSS in SmartSDR 1.6 is offered for RX in addition to TX modes?

I have seen the ability to set CTCSS for TX, but have not been able to figure out how to set a tone for RX tone squelching.


Mark K9BOO


  • George KF2T
    George KF2T Member ✭✭✭
    edited February 2019
    Think it's just on TX right now.
  • N6OIL
    N6OIL Member ✭✭
    edited September 2018
    Any movement on this yet?  I would love to try 6m FM repeaters the systems in my area have separate encode decode tones. 
  • Tore Andersson
    edited April 2020
    Do we have any official response from Flex about adding this ?
    I  use 2 transverters for 70 and 2 - and we have a lot of mixed mode repeaters in Sweden (both digital and analog) having the possibility to set tone on RX to open Squelch is very nice way of not needing to hear the digital traffic noice.

    73's de Tore
  • EA4GLI
    EA4GLI Member ✭✭✭
    edited May 2018
    Me too. Also, would love if frs could dedicate some time to improve the currently rudimentary FM mode on SmartSDR... Please.
  • Tim - W4TME
    Tim - W4TME Administrator, FlexRadio Employee admin
    edited May 2018
    At this time we are only sending CTCSS tones (on transmit).  There are not any near-term plans to do CTCSS decoding, but I have added your request for CTCSS controlled quelch functionality (feature #6193)
  • KQ4CFA
    KQ4CFA Member
    Is TX CTCSS a signal sent from my ratio up to the repeater to key the repeater? Is DX CTCSS a signal sent from the repeater down to my radio to key my radio? I ask these questions because I often see instructions to hit a repeater to just say tone or tone in or up and down arrows with the PL tone. I program my radio with either the required TX CTCSS or DX CTCSS and the offset and direction. Sometimes only one tone is provided and it will be indicated as "up" or "down" Very confusing.
  • KQ4CFA
    KQ4CFA Member
    I am a newly licensed Technician class Ham as of July 19, 2022. I have researched the CTCSS TX/DX question for days and it seems that one answer to my questions will contradict the answer provide by another person and I find my self in the unending loop. If some one could very simply define the signal direction of a TX CTCSS and DX CTCSS in relationship with the repeater It would be greatly appreciated.
  • George KF2T
    George KF2T Member ✭✭✭

    TX CTCSS is a sub audible tone designed to activate a repeater, instead of relying on just the presence of your signal. RX CTCSS is a tone sent by the repeater to open your receiver’s squelch, also instead of relying on the presence of a signal. Both can reduce noise and unwanted signals opening a repeater or your receiver. There is no “plus” or “minus” for tones; you may be looking at the repeater input to output frequency offset direction.

  • John KB4DU
    John KB4DU Member ✭✭✭✭

    And the tx tone is used when your radio is transmitting. The rx tone is used when your radio is receiving.

  • KQ4CFA
    KQ4CFA Member
    KB4DU and KF2T thank you both. I finally have been provided the simple direct answer to my question. BTW.... I have been programming my radio correctly.

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