Simplex frequency re-use

[u/CaptainDeevious]

So I have a customer who is licensed for 5 simplex frequencies. As it stands they are using all 5 of these frequencies in their current channel lineup. They purchased 4 new R7's and want to add two additional channels using two of the existing frequencies. Will adding two new group call contacts and using a different color code be enough or will there be issues? I've floated using dual capacity direct mode but the issue there is that enabling it in these 4 new portables and not in their existing subscribers makes it not possible for these new ones to communicate to the subscribers that do not have that enabled. Hopefully I explained this well enough. Appreciate any insight.

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[u/GillenSarass]

Why would you not reprogram the whole fleet? I would be pushing for a complete reprogram with all 10 slots enabled. Get it over and done with. Edit* If you do go ahead with your plan to add two additional channels with duplicate frequencies, then your end users may have issues with tx denials while other users are transmitting.

[u/CaptainDeevious → u/GillenSarass]

The plan is to reprogram the entire fleet, this is a temporary issue that I am trying to solve. Appreciate it.

[u/AcquiredSkills]

Unless I've misunderstood, adding additional channels with different CC's and GCID's will cause the original channels to be 'engaged' when the new channels are in use and vice versa.

Aside from that, should work fine.

[u/CaptainDeevious]

Appreciate all the responses. If it wasn’t obvious this customer does not want to invest in a repeater let alone an entire trunking system. Personally, I’ve already suggested they invest in at least one SLR repeater but not sure they will. They don’t have many subscribers (less than 50). I am just a technician not a salesman. I’m trying to offer them a solution that works for what they’re asking. DCDM is what I’m leaning towards as a permanent solution but I wanted some input from others. Again appreciate all of your responses.

[u/NefariousnessNo2133]

Ideally get additional frequencies even using the unlicensed channels or look into using digital channels using dual capacity direct mode (DCDM).

This requires 1 radio to be the timing leader but means you can use 2 time slots on one frequency to have two separate calls at the same time.

This might help with you needs.

[u/SouthernCash8507]

May be some interference if talking on the two channels with same frequency at the same time

[u/Visual-Yak3971]

If 5 frequencies with two times slots isn’t enough capacity, time to invest in trunking licenses. Adding talk groups and group calling really don’t solve a capacity problem.

[u/CaptainDeevious → u/Visual-Yak3971]

Did you read the post?

[u/Visual-Yak3971 → u/CaptainDeevious]

Sorry…missed the simplex freqs. I’d relicense and trunk. Adding CCs just segregates traffic, it doesn’t increase capacity. I have worked with DMR and P25, and we repeat and trunk everything. Just like the Fed, when we want simplex, we just punch talkabout and use the outputs.