Radioddity Extended manual for Radioddity DB25-D, DB40-D & GD-88 v3.0
© Radioddity 2023 page 189 of 252
13.26.7 Same Frequency Repeater digital to digital
The Radioddity DB40-D/GD-88 comes with a special feature called ‘Same
Frequency Repeater’, abbreviated as ‘SFR’. This functionality allows a single
Radioddity DB40-D/GD-88 to act as a DMR-repeater for a specific frequency and
a specific TalkGroup. This function is ideal for flexible emergency networks as
multiple Radioddity DB40-D/GD-88 allow to setup a kind of mesh-network. Whilst
receiving on one TimeSlot, the radio transmits the very same signal on the very
same frequency but on the other TimeSlot. So, RX TS1 → TX TS2 and RX TS2 → TX
TS1. As the Radioddity DB40-D/GD-88 has two fully independent VFOs (A and B) it
is required to setup two SFR-channels with one of them using TX TS1 and RX TS1
and the second one using TX TS2 and RX TS2 in order to allow SFR. Both VFOs do
share the same frequencies for TX and RX, the same ColorCode for TX and RX, the
same digital contact (of type Group Call) and the same RX-Group containing at
least that digital contact.
Then assign VFO A the SFR-channel with TX TS1
and RX TS1 and VFO B the SFR-channel with TX
TS2 and RX TS2.
If you have multiple Radioddity DB40-D and/or Radioddity GD-88, set all of them
up the very same way. Normal, non-SFR-capable dual VFO DMR radios should also
be setup the same.
Single-VFO radios such as the Radioddity GD-73 may of course only monitor one
SFR-channel at a time. So, if there is already a QSO ongoing, that single VFO-radio
may need to select the proper SFR-channel whenever only one of the two SFR-
channels is within coverage. But if the radio is located in the middle of two
DB40-D/GD-88 (thus hearing one Radioddity DB40-D/GD-88 TX on TS1 and
hearing the other Radioddity DB40-D/GD-88 TX on TS2) it may select either SFR-
channel.
Sample settings (only relevant parts shown):
The corresponding Radioddity DB25-D configuration for those two required SFR-
channels would be as follows (only those parameters are shown that are of
relevance). Keep in mind that the Radioddity DB25-D is not capable of acting as a
repeater using SFR. But of course it can be a station within a Radioddity
DB40-D/GD-88 based SFR mesh-network.
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