Duplex Hotspot Disconnect

[oh5bzr]

hi, if you add wire or if you can put second antenna difrently polarized it can hear better! This solved my proble + tuning first TXoffset and then using same software receive and minimize ber. I guess some kind duplexer could bee good idea.

[G8SEZ]

hi, if you add wire or if you can put second antenna difrently polarized it can hear better! This solved my proble + tuning first TXoffset and then using same software receive and minimize ber. I guess some kind duplexer could bee good idea.

As long as there is enough isolation on the PCB. The antenna positions are only 30-35mm apart and they share a ground plane which means that you need both antennas off the board so that any common mode ground currents are kept separated.

[M1DNS]

Basically... a hotspot is tx or rx. Simplex install or duplex install doesn't matter. 1x7021 chip or 2x 7021 chips, irrespective. server traffic Tx, no server traffic Rx.

On a repeater (true repeater) the rx is always listening locally.

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[Ae4g]

Ok, I obvs. misunderstood what you were trying to do. Now i know, Im still not aware of this as a feature of a hotspot board. If it's txing traffic, it can't get that drop request back to the server.



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Well, it depends on what you mean by "txing"...

Like a repeater, the duplex hotspots remain in TX mode for some period after someone has un-keyed. This time is adjustable using the "DMR TXHang" parameter in expert configuration.

When the duplex hotspot is still transmitting in this hang time, you can send a 4000 and it will disconnect.

It does not work (at least for me) while the other party is keyed.

It is clear that the hotspot sees me transmitting the 4000 even when someone else is keyed up (it shows up on my PiStar dashboard). It seems like the only thing missing is routing that 4000 request to Brandmeister.

[Ae4g]

Honestly I thought the same exact thing and didn't expect it to just ignore my keyup. I was also under the impression a duplex hat would disconnect at any time even if a transmission was happening .

I thought about it for a bit and I'm not sure its actually a problem with MMDVMHost, I think its actually in the MMDVM_HS firmware, and I'm not sure if it can ever support an interruption like that. I'll have to look into it and see.

Yes, this is turning out to be quite the disappointment.

Toshen says the below on his Amateur Radio Notes website:

"The duplex boards have one immediate advantage over the simplex hotspots, which is that you can transmit even when your radio is in the middle of receiving. This means that you can easily unlink from a busy talkgroup even when the hams using the TG don't leave gaps between their transmissions."

(bottom of page 19 here: https://amateurradionotes.com/images/10-hotspots.pdf )

I had read that, and other comments like it, before I purchased my duplex hotspot. That along with the fact that it works on my local DMR repeater made me believe that my duplex hotspot would work in the same way.

[Ae4g]

I think that there are quite a few changes in the HAT firmware since the 1.4.17 release, and indeed since the 1.5.1 beta, that relate to duplex hotspots.

I am not sure when Andy is planning to release the 1.5.x firmware, maybe the other Andy(s) know(s).

Thanks - I'll keep an eye out for the update.

[G8SEZ]

In the MMDVM_HS readme here:

https://github.com/juribeparada/MMDVM_H ... /README.md

It states:

"Full duplex support with two ADF7021"

so I suspect that the problem is either fixed in the currently unreleased firmware or that there is some other reason it's not being passed back to the server.

If the pistar log shows that it received the disconnect from the modem then it would be further up the stackin the MMDVM code.

[KD8DVR]

You cannot issue a disconnect while the hotspot is in an active situation. The hotspot must be idle for you to be able to issue a disconnect and have it acted on. As long as there is traffic it will not work.

My understanding of the concept (remember, /I/ don't have a duplex system myself) was that, with two frequencies in use, the hotspot can receive on the input frequency even while sending on the output frequency. But perhaps that requires full "repeater" configuration -- with separate external receive/transmit radios (though I thought duplex units had two flea-power radio modules on-board).

You can issue a disconnect on an active timeslot with a duplex hotspot....at least in my experience.


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[Ae4g]

You can issue a disconnect on an active timeslot with a duplex hotspot....at least in my experience.


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Interesting... You are the second person in the last 12 hours to tell me that it works for them (one was via email).

[Ae4g]

Which Duplex MMDVM_HS do you have? Either look for a name on the silkscreen or take a photo of it.

Its possible we are both using the same one, and theres an issue with it.

I don't think it is a hardware problem (at least not only a hardware problem). The reason I say that is because two hams that I trust both use N5BOC duplex hats - one can disconnect a busy time slot, one cannot...

Regardless, here are the pics of my generic duplex hotspot hat.