D-STAR on Fusion - HKE

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How to connect a D-STAR modem to a Yaesu DR-1X Fusion repeater.

For some months ago, Hamargruppen av NRRL bought a Fusion DR-1XE repeater to test and compare D-STAR and Fusion.   We found that Fusion is a bit better regarding speech quality.  
We had some DVRPTR D-STAR modems, so we started to investigate in how to easily connect the D-STAR modem to our Fusion repeater, and we come up with the solution described.
See bottom of page to buy a ready made PCB.

The DR1-XE is a digital and analog repeater, if the RX is receiving an analog signal, the analog signal will be transmitted, and so with a Fusion digital signal.  Our aim was to find a way to connect the the D-STAR modem so the repeater would be either Fusion, analog or D-STAR.  

After some thinking and Googling, we found a simple solution.  What`s needed was just a simple switch for connecting the PTT an TX audio for the Fusion TX, from either D-STAR modem or Fusion RX.
We wired this up with the necessary components, and our Fusion repeater was still working with the switch circuit.  We then connected our DVRPTR modem to the switch, and we achieved what we wanted. When transmitting a D-STAR signal to the repeater, the D-STAR signal was transmitted from the DVRPTR modem board, and when transmitting a Fusion signal, this was transmitted as earlier.
The schematic is quite simple, a 3.3V regulator IC and a 74HC4052 Multiplexer and Demultiplexer IC.  PTT from DVRPTR modem or RX squelch signal from Fusion RX is selecting the gate to be used (A and B input on the IC), selecting the input signal to be output to Fusion TX on X (PTT) and Y (AF).

Connecting the PCB:
I have made a PCB for the circuit to be installed in the DR-1XE repeater.


Locate the cable connecting the Fusion RX and TX (see photo below).  The cable is having a USB3.0 type connector at the RX end and and a 10 pin MiniDin at the TX end.  This cable has to be cut, as we need the TX audio and RX squelch signals for the switch circuit. Cut the cable about 20-25 cm from the RX end, and solder the wires to the printed circuit bord.  The PCB is marked with the wire colours, and make sure the correct wire is connected to the solder pads.  D-STAR modem is connected with a 6-pin MiniDin cable.  The PCB needs +12V power supply, and the red (+) and black (-) leads can be soldered to the Fusion Relay Unit PCB using solder terminals on the PCB marked + and -  (see photo below).  Power for the DVRPTR modem can be connected to the Fusion Relay PCB or LA1BR PCB.
The D-STAR modem needs flat RX audio (unfiltered).  The audio supplied to the cable we just cut is not flat when Fusion RX is in analoge mode (Fusion RX is detecting the D-STAR signal as an analog signal), so the DVRPTR will not decode OK using this audio.  The audio out pin (8) on the 15 pin DSUB connector located at the rear of the repeater, is having a flat audio response, so this audio is OK for decoding D-STAR.  Connect a wire from pin 8 of the DSUB to terminal named AF on the LA1BR PCB.

When receiving a D-STAR signal, the Fusion recognises this signal as an analog signal.  If a CTCSS tone is selected in the Fusion, the D-STAR signal will not be re-transmitted by the Fusion repeater, only by the DVRPTR modem.  The repeater will not work in D-STAR mode if a CTCSS tone is not selected.
The RX and TX must be set to AUTO.  
The repeater is also having a callsign, and this should be the same entered in the DVRPTR modem and Fusion repeater.  
The DVRPTR modem is having a GUI where several parameters have to be set, and you also have to adjust the level of the TX audio.  We set this to about 2kHz deviation.  Some Icom radios is not decoding OK if the deviation is too high.  If you don`t have a deviation meter to connect to the TX, you can use 2 D-STAR radios.  Transmit with one radio and adjust the audio level of the DVRPTR until the other radio is having a good audio quality of your speech.

A PCB can be bought from LA1BR.  The PCB is delivered with all components soldered, power supply wires (red = +, black = -) to be soldered to the Fusion Relay PCB, 15pin DSUB HD connector, and cable with MiniDin connectors for the D-STAR modem.

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