PTT serves us well on DMR for routing and timing of talkgroups. Part 97 does not expressly speak to disallowing its use directly. Potentially, don’t ask and don’t tell may be applicable for DMR.

How to interpret PTT and Part 97 as it may apply to DMR

PTT and Kerchunking are NOT expressly prohibited by the FCC. The rule of thumb is that brief transmissions to enable communications is permitted (97 .111(b)(2)). One does NOT need to ID at the beginning of a transmission or conversation. One MUST ID a transmission or series of transmission (communication) at least once every 10 minutes or at the end of a series of transmissions (conversation) (97.119(a)). It is that simple. See the cites at bottom of the page.

Now in the context of DMR, repeaters and networking of repeaters over PNWDigital, here are the bulletpoints supporting PTT:

  • PTT / Kerchunk is a brief transmission and need not be ID’ed to turn on a talkgroup.
    • ID must be done within 10 minutes, better sooner when you gain voice control when you make a call.
  • A talkgroup change does not “require” an ID if you are TX’ing to the same repeater (no transmit frequency change)
    • But it’s a good idea as you have the talkgroup anyway and it’s a standard courtesy.
  • Kerchunking repeatedly is not a FCC consideration (though it may be annoying)
    • As you are not changing frequency
    • You only need to ID at the end of your series of transmissions or every 10 minutes during that series.
    • But you should pause for effort or to change a control setting, IE: don’t be a lid.

PTT, Push-to-Talk or Kerchunking is a primary and necessary way to route, control, enable and diasble traffic on DMR networks. Multi-talkgroup DMR networks would is very hobbled if PTT is not made a significant port operational component of the network. It would be similar to the chaos of removing CTCSS and DCS from FM repeater input control.

If you wish to interpret Part 97 rigidly and rather use a workaround method, then:

  • Don’t kerchunk; make it a call, ID your station, state what your are doing or why or whatever communication you feel fits the situation.
  • If you kerchunk and want to ID but not into a current QSO, do it over local on the opposite timeslot using the same repeater.

§ 97.111 Authorized transmissions.

(b) In addition to one-way transmissions specifically authorized elsewhere in this part, an amateur station may transmit the following types of one-way communications:

(2) Brief transmissions necessary to establishing two-way communications with other stations;

§ 97.119 Station identification.

(a) Each amateur station, except a space station or telecommand station, must transmit its assigned call sign on its transmitting channel at the end of each communication, and at least every 10 minutes during a communication, for the purpose of clearly making the source of the transmissions from the station known to those receiving the transmissions.

First Published: September 21, 2021 Last Updated: 10 months ago by Mike – NO7RF

Views: 2118

Leave a Reply