UV380 + DM-1701 Beta 2023 03 08
Re: UV380 + DM-1701 Beta 2023 03 08
AFIK the official firmware does. Not. include SFR
Re: UV380 + DM-1701 Beta 2023 03 08
Yes, as mentioned before we know the the radio can do DCDM but we don't know how to do it!
As Roger said, DCDM seems to be a vendor specific feature and as such is not well documented in the ETSI DMR spec. Likewise the limited HRC6000 documentation barely mentions it.
It might be possible to generate transmissions containing the correct sync words so that they looked like DCDM transmissions, but the main problem is how to maintain the synchronisation between radios to keep the timeslots aligned. That synchronisation algorithm is the proprietary part.
I theory you could probably build a SFR that did not use DCDM. (With suitable hardware, not with OpenGD77) If it synchronised to the incoming Direct mode transmission it could repeat that on the unused timeslot even without using DCDM. Handhelds that could only hear the repeater would just hear a normal Direct mode transmission and work fine. Handhelds that could hear both the repeater and the other handheld might however get confused when receiving both timeslots. The behaviour would be undetermined. There are some experiments being done using two frequency direct mode. That would certainly get around the two timeslot problem.
Colin G4EML
As Roger said, DCDM seems to be a vendor specific feature and as such is not well documented in the ETSI DMR spec. Likewise the limited HRC6000 documentation barely mentions it.
It might be possible to generate transmissions containing the correct sync words so that they looked like DCDM transmissions, but the main problem is how to maintain the synchronisation between radios to keep the timeslots aligned. That synchronisation algorithm is the proprietary part.
I theory you could probably build a SFR that did not use DCDM. (With suitable hardware, not with OpenGD77) If it synchronised to the incoming Direct mode transmission it could repeat that on the unused timeslot even without using DCDM. Handhelds that could only hear the repeater would just hear a normal Direct mode transmission and work fine. Handhelds that could hear both the repeater and the other handheld might however get confused when receiving both timeslots. The behaviour would be undetermined. There are some experiments being done using two frequency direct mode. That would certainly get around the two timeslot problem.
Colin G4EML
Re: UV380 + DM-1701 Beta 2023 03 08
The TRx chip in the UV380 and GD77 does not seem to be able to switch between Tx and Rx to sustain SFR.
DCDM does not need to constantly switch between Tx and Rx.
AFIK, the reason that DCDM exists is for commercial users who pay per channel frequency, to have 2 users use the same frequency , hence saving money.
Ham radio does not have this need
DCDM does not need to constantly switch between Tx and Rx.
AFIK, the reason that DCDM exists is for commercial users who pay per channel frequency, to have 2 users use the same frequency , hence saving money.
Ham radio does not have this need