Why ETC ARES uses PL Tones on Simplex

Introduction

We ask all of our ETC ARES Team members to program their radios to transmit and receive (encode AND decode) a 103.5 Hz sub-audible tone on our team simplex frequency 146.550 MHz.   The suggested alpha tag for this channel in your radio is "ETC-1d".   Sub audible tones are commonly referred to as CTCSS or PL.

For many hams, using sub-audible tones on simplex may seem unusual.   This article will explain the reasoning behind our use of PL tones on our ETC ARES Team simplex channel.  

Excluding Non-team Traffic

Our team frequency is used by many other hams.   There is a reqular Saturday evening simplex net on 146.550 MHz called the "Double Nickel" net.   The Olympia LDS Church holds EMCOMM nets on 146.550 MHz.   There is a Pierce County ARES team that uses 146.550 MHz as "their" team frequency.   While some of this traffic may be interesting to us as ordinary hams, it potentially interferes with team communications during an actual event.   In the case of the Pierce County ARES team, past experience has shown that their radio traffic is received by many of our ETC ARES team members whenever they are active.   By programming the "ETC-1d" channel to only unsquelch the radio when the team's 103.5 Hz tone is present, you won't hear all of this other traffic.

24/7 Monitoring

We ask each of our ETC ARES Team members to leave a radio set to the team simplex frequency for monitoring at all possible times.   If there is an unscheduled/emergency team activation, or if someone has emergency traffic for the team, all team members that have dedicated a radio to listen for traffic will hear it on this "guard" radio.   Using tone decode on these "guard" radios helps to eliminate non-team-related traffic from waking us up from a good snooze.

Net Control

If everyone has tone decode set during a team event where we are using our ETC ARES Team simplex frequency, how will we know if we are causing interference to other hams on the frequency?   The answer to this is Net Control.   Our ETC ARES Net Control station(s) should have a "net control" channel programmed into their radio(s) that encodes tone but DOESN'T decode tone.   In this way, they can monitor for interference while still being heard by all of the ETC ARES Team members.   The suggested alpha tag for this channel in your radio is "ETC-1dnc".

Another way for Net Control to monitor for interference would be to use a second radio in their shack that has the "ETC-1dnc" channel programmed into it.   Then they'd be able to use the "ETC-1d" channel on their primary radio to run net operations without interference on the primary radio.   Remember to take the necessary precautions for the secondary radio to protect it from being overloaded/damaged by the RF from the transmissions of the primary radio.

Hint: All ETC ARES Team members should prepare themselves to eventually take over as a Net Control.   Please consider adding a "net control" channel to your radio or even a secondary radio to your shack as suggested above.

Conclusion

We use tone encode/decode on our ETC ARES Team simplex frequency to enable 24/7 monitoring and to improve net efficiency when other users (especially distant ones) are active on our channel.   We rely on Net Control to monitor for and mitigate any interference our team tone-encoded simplex operations may cause.  

---